- Email: [email protected]
Room temperature magnetoelectric coupling effect in CuFe2O4-BaTiO3 core-shell and nanocomposites
Accepted Manuscript Room temperature magnetoelectric coupling effect in CuFe2O4/BaTiO3 core-shell and mixed nanocomposites Rahul Mundiyaniyil Thankachan, B. Raneesh, Anshida Mayeen, S. Karthika, S. Vivek, Swapna S. Nair, Sabu Thomas, Nandakumar Kalarikkal PII:
S0925-8388(17)33371-6
DOI:
10.1016/j.jallcom.2017.09.309
Reference:
JALCOM 43365
To appear in:
Journal of Alloys and Compounds
Received Date: 13 June 2017 Revised Date:
28 August 2017
Accepted Date: 27 September 2017
Please cite this article as: R.M. Thankachan, B. Raneesh, A. Mayeen, S. Karthika, S. Vivek, S.S. Nair, S. Thomas, N. Kalarikkal, Room temperature magnetoelectric coupling effect in CuFe2O4/ BaTiO3 core-shell and mixed nanocomposites, Journal of Alloys and Compounds (2017), doi: 10.1016/ j.jallcom.2017.09.309. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
AC C
EP
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
ACCEPTED MANUSCRIPT
Room temperature magnetoelectric coupling effect in CuFe2O4/BaTiO3 core-shell and mixed nanocomposites Rahul Mundiyaniyil Thankachan1, B. Raneesh1*, Anshida Mayeen2, S. Karthika1, S. Vivek3,
RI PT
Swapna S. Nair3, Sabu Thomas4,5 and Nandakumar Kalarikkal2,5
Department of Physics, Catholicate College, Pathanamthitta, Kerala-689 645, India
2
School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam 686 560, India
3
Department of Physics, Central University of Kerala, Kasaragod 671 314, India
4
School of Chemical Sciences, Mahatma Gandhi University, Kottayam 686 560, India
5
International & Inter University Centre for Nanoscience and Nanotechnology, Mahatma Gandhi
*
M AN U
University, Kottayam, Kerala-686 560, India
SC
1
Corresponding author. E-mail address: [email protected]
Abstract
Novel magnetoelectric (ME) CuFe2O4@BaTiO3 core-shell and (1-x)BaTiO3-xCuFe2O4 (x=0.1,
TE D
0.3, 0.5, 0.7 and 0.9) mixed composites were prepared by two step sol-gel and a sol-gel followed by a solid state reaction respectively. Crystal structure and microstructure of the samples were examined using X-ray diffraction (XRD) and transmission electron microscopic (TEM) techniques. The ferroelectric and magnetic properties of the materials were confirmed by
EP
polarization versus electric field (P-E) and magnetization versus magnetic field (M-H) measurements respectively. To determine the coupling between ferroelectric and magnetic orderings, ME coupling studies were performed using a lock-in amplifier setup. The highest
AC C
value of the ME coupling coefficient (α) was noticed for the CuFe2O4@BaTiO3 core-shell (α = 22.5 mV cm-1 Oe-1) sample. Superior ME coupling behavior in the core-shell material is due to better connectivity between the ferroelectric and magnetic phases. The optical measurements indicate the possibility of easy manipulation of the band gap over a range of energies by mere control of the molar ratio of the phases. The smart architecture enables CuFe2O4@BaTiO3 sample to be a highly promising material for the design of devices based on ME multiferroics. Keywords: Multiferroic; core-shell; mixed nanocomposite; magnetoelectric coupling
ACCEPTED MANUSCRIPT
1. Introduction Magnetoelectric multiferroic (MF) materials are currently a main area of research due to its high technological significance in the modern civilization[1,2]. Possibility to manipulate the electrical
RI PT
property by a magnetic field and vice versa makes it an apt material for many demanding applications such as multiple-state memory elements, ME sensors, high-frequency filters, actuators and more[3–6]. From a technological perspective, a sizeable ME response at room temperature is necessary in order to utilize its full potential. Even though the ME response has been noticed as an intrinsic effect in single phase materials [7], the observed ME coupling in
SC
such a MF material is usually too feeble for an appropriate device performance[8]. During the past several years, some elegant strategies such as doping [9], particle size reduction [10] and
M AN U
ferroelectric-magnetic composite architecture [11] have been employed to develop the room temperature MF materials. As compared to single phase MF, composite MF material prepared by combining suitable ferroelectric and magnetic phases offers remarkable ME behavior [12]. In such an engineered MF material, ME coupling is an extrinsic property and may arise directly between the two order parameters, or indirectly via strain [13,14]. The ME properties in a composite MF material can be easily controlled by adjusting the volume fractions of the
TE D
individual phases[15]. In addition to the volume fractions and properties of the individual phases, the type of connectivity among the phases has a predominant effect on the ME coupling properties [16,17]. The composite ceramic MF materials synthesized by the conventional method (direct mechanical mixing of ferroelectric and magnetic phases) exhibited a weak ME effect
EP
mainly due to the low percolation threshold (~ 18%) in the magnetic phase[15]. Better intercalation and promising connectivity between the phases can be achieved by a core-shell
AC C
design consisting of a magnetic core and ferroelectric shell [18,19]. Several MF composites have been reported. Some of the composites that have been studied are (1-x)Ba0.95Sr0.05TiO3-(x)Ni0.7Zn0.2Co0.1Fe2O4 Ni0.5Zn0.5Fe2O4+Pb(Zr0.48Ti0.52)O3 BaTiO3−MgFe2O4
[24],
[22],
[20],
Sr3CuNb2O9–CoFe2O4
[21],
0.65BaTiO3–0.35Bi0.5Na0.5TiO3–BiFeO3
Ni0.5Zn0.5Fe2O4@BaTiO3
[25],
CoFe2O4@BaTiO3
[26]
[23], and
BaTiO3@Fe2O3 [27]. However, as far as the authors know there are no reports on the preparation and characterization of CuFe2O4/BaTiO3 core-shell and mixed nanocomposites MF systems. CuFe2O4 (CFO) has been selected as the magnetic phase because of its high saturation magnetization and high Neel temperature (TN=780±20 K)[28,29] and BaTiO3 (BTO) as the
ACCEPTED MANUSCRIPT
electrical counterpart due to its superior room temperature ferroelectric nature. Usually, most of the spinel ferrites exhibit cubic crystal structure[30]. But copper ferrite is a special candidate and can show cubic and tetragonal symmetries [31]. The crystallization of tetragonal crystal phase is favorable if the sample is slowly cooled from high temperatures[28,29]. The Curie temperature
RI PT
Tc reported for barium titanate is around 1300C. Above the Curie temperature, BTO undergoes a transition from its ferroelectric tetragonal phase to paraelectric cubic phase [32,33]. The ferroelectric polarization in the tetragonal crystal geometry of BTO is a result of the permanent electric dipole created by the displacement of titanium from the octahedron center to an off-
SC
center position[32,34]. In this paper, we present the results of the structural and morphological characterizations, electric, magnetic, magnetoelectric and optical studies of the novel CFO/BTO
M AN U
core-shell and mixed nanocomposite MF materials. 2. Experimental details 2.1 Materials
Cupric (III) nitrate trihydrate (Cu(NO3)2 · 3H2O), ferric (III) nitrate nonahydrate (Fe(NO₃)₃ . 9 H₂O) citric acid (C6H8O7) and ethylene glycol (C2H6O2) were purchased from Merck and used without further modification. Barium acetate (Ba(C2H3O2)2) titanium-tetra isopropoxide
2.2 Sample preparation
TE D
(Ti[OCH(CH3)]4) were purchased from Sigma Aldrich and used without further purification.
Preparation of CuFe2O4 nanoparticles: CuFe2O4 nanoparticles were synthesized by sol-gel
EP
method as described elsewhere[35,36]. At first, 0.2 M of cupric nitrate trihydrate and 0.4 M of ferric nitrate nonahydrate were dissolved in 100 mL double distilled water. To the solution, 5.24
AC C
g citric acid was added. The solution thus obtained was stirred for several hours and the homogeneous solution was maintained at 80 0C until a dried gel was formed. The dried gel was calcined at 800 0C for 5 h.
Preparation of BaTiO3 nanoparticles: BaTiO3 nanoparticles were prepared by the polymeric organometallic precursor method (Pechini method)[10,37]. Initially, separate citrate solutions of barium acetate and titanium tetra isopropoxide were prepared[38]. In the subsequent step, citrate solutions were mixed together and stirred at 90 0C. After the homogeneous mixing, the solution was maintained at 120 0C to promote polymerization and the removal of solvents. Finally, the dried gel was calcined at 800 0C for 5 h.
ACCEPTED MANUSCRIPT
Preparation of xCuFe2O4–(1-x)BaTiO3 mixed nanocomposites: The composite samples were prepared by mixing stoichiometric amounts of the CuFe2O4 and BaTiO3 phases using an agate mortar and pestle.
RI PT
Preparation of CuFe2O4@BaTiO3 core-shell nanoparticles: To obtain the CuFe2O4@BaTiO3 core-shell structure with 1:1 ratio of CuFe2O4 and BaTiO3 phases, 1.11 mL of titanium-tetra isopropoxide, 0.96 g barium acetate and 0.5 g citric acid were homogeneously mixed in a solvent composed of 25 mL water and 25 mL ethylene glycol. To the solution, 0.89 g of the prepared CuFe2O4 nanoparticles was uniformly dispersed by sonication. The solution was maintained at
SC
120 0C with continuous mechanical stirring. The dried gel thus obtained was calcined at 800 0C for 5 h [39]. The overall material preparation procedure of CuFe2O4@BaTiO3 core-shell sample
EP
TE D
M AN U
is schematically described in Fig. 1.
AC C
Fig. 1 Schematic illustration of the CuFe2O4@BaTiO3 core-shell material synthesis procedure. 2.3 Characterization
In this study, all the measurements were carried out at room temperature. XRD data were recorded over a range of 20-800 from the powder samples using Rigaku, MiniFlex 600 powder X-ray diffractometer with a Cu-Kα radiation source. The morphological images of the samples were captured by JEOL JEM 2100 transmission electron microscopy operating at 200 kV. Energy Dispersive X-ray (EDX) analysis was used to check the presence of various elements
ACCEPTED MANUSCRIPT
present in the sample. Ferroelectric loops were recorded by Marine India PE-01 loop tracer. Magnetic measurements were conducted using Versa lab, Quantum Design multifunctional vibrating sample magnetometer (VSM). To test the MF property, ME coupling measurements were carried out using lock-in amplifier ME coupling setup (Marine India). The linear optical
RI PT
studies of the samples were performed using Agilent Cary 5000 UV-Vis spectrophotometer in the wavelength range 200-800 nm. 3. Results and discussion
TE D
M AN U
SC
3.1. Structural analysis
composites.
EP
Fig. 2 XRD patterns of BTO, CFO, CFO@BTO core-shell and CFO-BTO (x=0.1 to 0.9) mixed
AC C
Fig. 2 shows the powder XRD patterns of the BTO, CFO, CFO@BTO core-shell and CFO-BTO (x=0.1 to 0.9) mixed composites. All the pronounced diffraction peaks of BTO can be indexed to a tetragonal crystal system (JCPDS 89-1428, space group P4mm) with lattice parameters of a=3.99
and c=4.03 . CFO diffraction peaks also belong to a tetragonal crystal structure
(JCPDS 34-0425, space group 141/amd) with lattice parameters of a=5.84
and c=8.63 . The
diffraction peaks at 22.13, 31.52, 38.91, 45.22, 50.91, 56.13, 65.82 and 70.43 are associated with the 001/100, 101/110, 111, 200, 201, 112/211, 202/220 and 212/300 reflections of BTO and the peaks at 29.95, 30.68, 34.55, 36.00, 37.23, 41.76, 43.81, 53.99, 55.10, 57.09, 58.10, 62.06 and
ACCEPTED MANUSCRIPT
64.13 represent the 112, 200, 103, 211, 202, 004, 220, 312, 105, 303, 321, 224 and 400 reflections of CFO, indicating the successful formation of the BTO and CFO crystal phases. According to the Scherrer equation[5], the average sizes of the primary crystallites were calculated to be 21 nm and 34 nm for BTO and CFO samples, respectively. The XRD diffraction
RI PT
patterns of the core-shell and the mixed composites show the characteristic peaks of the CFO and BTO phases. The intensity of the CFO peaks gets intensified with the increase of the CFO content in the mixed composites. The non-existence diffraction peaks other than tetragonal CFO and tetragonal BTO phases indicate the absence of impurities in the core-shell and mixed
SC
composites. 3.2. Morphological analysis
M AN U
Fig. 3(a) shows the TEM image of the 0.7CFO-0.3BTO mixed composite sample. It shows the agglomerated nanoparticles of the mixed composite. The corresponding high-resolution transmission electron microscopic (HRTEM) image of the 0.7CFO-0.3BTO mixed composite is shown in Fig. 3(b). The interplanar spacing of 0.28 nm in the HRTEM image represents the (101)/(110) plane of the BTO phase and the interplanar spacing of 0.249 nm corresponds to the (211) lattice plane of the CFO. The selected area electron diffraction (SAED) pattern shown in
AC C
EP
TE D
Fig. 3(c) points out the crystalline nature of the 0.7CFO-0.3BTO mixed composite.
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 3 (a) TEM image of 0.3BTO-0.7CFO mixed composite (b) corresponding HRTEM image and (c) SAED pattern.
EP
Fig. 4(a) and (b) show the TEM images of the CFO@BTO core-shell MF material under different magnifications. The core and shell structure of the CFO@BTO is clearly seen in the
AC C
Fig. 4(b). The diameter of the core calculated from the TEM image was 35.6 nm and the thickness of the shell was 31.7 nm. HRTEM image of the CFO@BTO core-shell (Fig. 4(c)) shows the well-defined lattice fringes of the core CFO and shell BTO and the calculated dspacing of the core (0.25 nm) and shell (0.28 nm) are in agreement with the d-spacing of (211) plane of the CFO and (110)/(101) plane of the BTO respectively. Furthermore, the SAED pattern shown in the inset of Fig. 4(c) indicates the crystallinity of the core-shell MF material.
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 4 (a) and (b) TEM images of CFO@BTO core-shell sample under different magnifications
EP
(c) corresponding HRTEM image, the inset represents the SAED pattern (d) the EDX spectrum.
To analyze the presence of various elements, EDX study was performed on the CFO@BTO
AC C
core-shell material. The EDX analysis (Fig. 4(d)) depicts only the peaks of copper, iron, barium, titanium and oxygen. This further confirms the purity of the synthesized CFO@BTO core-shell MF material.
3.3. Ferroelectric studies
P-E loops of the CFO-BTO mixed composites (x=0.1, 0.3, 0.5 and 0.7) and CFO@BTO coreshell have been recorded at a fixed frequency of 50 Hz and are shown in Fig. 5. The observed PE loops confirming the ferroelectric nature of the samples[40]. It is noticeable from the Fig. 5 that the ferroelectric loops are not saturated, a reason for such a behavior of the composite MF is the leakage current in the system due to the presence of the magnetic counterpart[41,42]. The
ACCEPTED MANUSCRIPT
measured values of the ferroelectric parameters such as maximum polarization (Pmax) and remnant polarization (Pr) from the P-E loops are listed in Table 1. The increase of the ferrite content reduces the availability of the ferroelectric nanoparticles as well as enhances the leakage current nature of the composite MF system. This combined effect resulted in the reduction of the
RI PT
maximum polarization value as noticed in Table 1. Even though the molar weight fractions of the ferroelectric and magnetic phases are equal in the CFO@BTO core-shell MF material, its maximum polarization value is close to the 0.1CFO-0.9BTO mixed composite sample. Since the ferroelectric phase is far more electrically insulating than the magnetic particles, such a coating
SC
isolate the conducting CFO particles from one another and effectively reduces the leakage current [15,19]. So the remarkable ferroelectric behavior noticed in the CFO@BTO core-shell
M AN U
sample can be attributed to the proper coating of the BTO phase over the magnetic core [19].
Table 1. Ferroelectric parameters of the CFO@BTO core-shell and CFO-BTO mixed composites.
Ferroelectric Parameters
Sample
0.610
TE D
CFO-BTO (x=0.1)
Pmax (µC/cm2)
Pr (µC/cm2)
0.113
0.372
0.065
CFO-BTO (x=0.5)
0.265
0.064
CFO-BTO (x=0.7)
0.195
0.083
CFO@BTO
0.594
0.101
AC C
EP
CFO-BTO (x=0.3)
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 5 PE loops of the CFO@BTO core-shell and CFO-BTO mixed composites (x=0.1, 0.3, 0.5 and 0.7).
3.4. Magnetic studies
TE D
To understand the magnetic nature of the CFO@BTO core-shell and CFO-BTO mixed composites, VSM measurements were carried out at room temperature and the curves thus obtained are shown in Fig. 6(a) and (b). Saturated M-H hysteresis loops have been noticed in all the samples studied, indicating the presence of magnetic ordering[43]. The magnetic parameters
EP
such as saturation magnetization (MS), remnant magnetization (Mr) and coercive field (Hr) are listed in Table 2. The Ms value of the composites increases from 2.39 emu/g to 28.36 emu/g with the increase of the CFO molar weight fraction from x=0.1 to 0.9. In the CFO@BTO core-shell
AC C
MF material, a saturation value of 17.87 emu/g has been noticed. It is evident from the Table 2 that coercivity of CFO@BTO is almost two fold higher than that of the CFO-BTO mixed composites. This may be due to the reduced movement of surface spins of the ferrite particles caused by the barium titanate coating[44,45]. So the high value of coercivity as observed in CFO@BTO can be taken into consideration to understand the better coating of ferroelectric material over the magnetic phase.
RI PT
ACCEPTED MANUSCRIPT
BTO mixed composites (b) low field region (±10 kOe).
SC
Figure 6 (a) Magnetization versus magnetic field curves of CFO@BTO core-shell and CFO-
M AN U
Table 2. Magnetic parameters of the CFO@BTO core-shell and CFO-BTO mixed composites. Magnetic Parameters
Sample
Ms (emu/g)
Mr (emu/g)
Hr (kOe)
2.39
1.15
0.70
CFO-BTO (x=0.3)
7.29
3.58
0.66
CFO-BTO (x=0.5)
12.24
5.96
0.59
CFO-BTO (x=0.7)
17.48
8.20
0.72
CFO-BTO (x=0.9)
28.36
10.94
0.73
CFO@BTO
17.87
8.95
1.35
EP
TE D
CFO-BTO (x=0.1)
3.5. Magnetoelectric studies
To check the interactions of magnetic and electric orders at the atomic level, the ME coupling
AC C
coefficients of the CFO-BTO mixed composites CFO@BTO core-shell have been determined by lock-in amplifier method[46,47]. A detailed description of the ME coupling experimental can be found elsewhere[11,46]. The variations of ME voltage with AC magnetic field of the CFO-BTO mixed composites and CFO@BTO core-shell are shown in Fig. 7(a). The measurements have been conducted by varying the AC magnetic field (frequency 850 Hz) from 0 to 80 Oe in the presence of a constant DC bias magnetic field (Hdc) of strength 2 kOe. The measured ME voltage shows a linear increase with the applied AC magnetic field and the linear ME coupling coefficient α, was calculated using the equation [21,26,48],
ACCEPTED MANUSCRIPT
α=dE/dH = (1/t)(dV/dH)=Vout/ht where Vout denotes the ME voltage generated across the sample surface, h represents the amplitude of the applied AC magnetic field, and t is the thickness of the sample. The obtained α values of the core-shell and mixed composites are listed in Table 3. The experimental results
RI PT
reveal that all the samples exhibit ME coupling at a DC magnetic bias of 2 kOe. Among the various mixed composites, highest α is noticed for the 0.7CFO-0.3BTO sample. However, CFO@BTO core-shell material exhibits α =22.5 mV cm-1 Oe-1 which is higher than that of the 0.7CFO-0.3BTO mixed composite sample. In case of multiphase MF materials, the coupling is
SC
expected to originate at the interface between the two dissimilar ferroic phases [49,50]. The improved mechanical coupling between ferroelectric and magnetic phases accounts for the high
M AN U
value of ME coupling evolved in the CFO@BTO core-shell material[51]. In the DC ME coupling measurements, generated ME voltage has been detected while varying the DC magnetic field from 0 to 5 kOe in the presence of an AC magnetic field of frequency 850 Hz and strength 10 Oe. The coupling coefficients of the various samples from the DC measurement have been found out by dividing the detected ME voltages by the AC magnetic field strength [46] and the curves thus obtained are shown in Fig. 7(b). The ME coupling coefficients of the samples shown
AC C
EP
TE D
in Fig. 7(b) are in agreement with the values listed in Table 3.
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 7 (a) Variation of ME voltage with AC magnetic field and (b) variation of ME coupling coefficient with DC magnetic field of CFO@BTO core-shell and CFO-BTO mixed composites.
EP
Table 3. ME coefficients of the CFO@BTO core-shell and CFO-BTO mixed composites. α (mV cm-1 Oe-1)
CFO-BTO (x=0.1)
5.15
AC C
Sample
CFO-BTO (x=0.3)
10.31
CFO-BTO (x=0.5)
12.93
CFO-BTO (x=0.7)
15.63
CFO-BTO (x=0.9)
14.66
CFO@BTO
22.50
ACCEPTED MANUSCRIPT
3.6. Linear optical studies Band gap energy is a characteristic feature of all the materials and can be estimated using a UVvisible spectroscopic technique. The band gaps of the materials in the present study were determined by assuming as direct type [23,52–59] and calculated using Tauc’s law, (αhʋ)2 = hʋ-
RI PT
Eg, where h is the Planck constant, α the linear absorption coefficient and Eg is the band gap energy[60,61]. For the band gap calculation, we have plotted (αhʋ)2 against hʋ and are shown in Fig. 8. The linear portion of the curve characterizes the fundamental absorption property of the material[53]. The band gap values were determined by extrapolating the linear portion of (αhʋ)2
SC
versus hʋ plot to the point (αhν)2 =0[62,63]. The Eg value of the CFO, BTO, CFO-BTO mixed composites and CFO@BTO core-shell are shown in Table 4. The obtained band gaps of CFO
M AN U
and BTO are in agreement with the values from previous reports [23,52–59]. The band gap energy of the mixed composite decreases with the increase of CFO content. This could be due to
AC C
EP
TE D
the less band gap value of the CFO as compared to BTO.
Fig. 8 (αhν)2 versus hν plots of BTO, CFO, CFO@BTO core-shell and CFO-BTO mixed composites.
ACCEPTED MANUSCRIPT
Table 4 The band gap value of BTO, CFO, CFO@BTO core-shell and CFO-BTO mixed composites. Sample
Band Gap
CFO-BTO(x= 0.1)
3.22
CFO-BTO (x=0.3)
3.16
CFO-BTO (x=0.5)
3.07
CFO-BTO (x-0.7)
2.85
CFO-BTO (x=0.9)
2.21
CFO@BTO
2.40
CFO
4. Conclusions
SC
3.25
M AN U
BTO
RI PT
Eg (eV)
1.9
CuFe2O4@BaTiO3 core-shell and xCuFe2O4–(1-x)BaTiO3 mixed nanocomposites were synthesized. Successful formation of the BTO and CFO crystal phases were verified in all the
TE D
samples by XRD analysis. The morphological character of the x=0.7 mixed composite and CFO@BTO core-shell were analyzed through TEM imaging. Ferroelectric properties of the CFO-BTO mixed composites were decreased with the increase of CFO molar weight fraction from x=0.1 to 0.9 but consequently, it induced high saturation magnetism. The proper coating of
EP
the BTO shell on the CFO phase causes a reduction of the leakage current in the CFO@BTO core-shell sample and thereby it exhibited ferroelectric parameters close to the x=0.1 mixed
AC C
composite sample. A high saturation magnetization of 17.87 emu/g has been perceived in the CFO@BTO core-shell material and the envisaged high coercivity explains the better interaction of the CFO and the BTO phases. Room temperature ME coupling was observed in all the CFOBTO mixed composites but the coupling coefficient noticed in the CFO@BTO core-shell was higher than that of the CFO-BTO mixed composites. The enhancement in the ME coupling coefficient as observed in the core-shell MF sample is a direct consequence of the improved connectivity between the BTO-ferroelectric and CFO-magnetic phases. UV-Vis characterizations suggest the feasibility of band gap tuning over a range of energies by controlling the molar ratio
ACCEPTED MANUSCRIPT
of the CFO and the BTO phases. It is believed that this work will be highly useful for the design of ultra-modern devices based on magnetoelectric multiferroics.
Acknowledgements
RI PT
The authors acknowledge the financial support from SERB - Govt. of India through ECR project scheme (ECR/2015/000536). Authors also acknowledge the use of X-ray diffraction facilities at St. Thomas College, Palai, India. The authors thank Mr. Anu A S for the TEM imaging and EDX
SC
analysis and Dr. Praveen G for UV-Vis measurements.
References
H. Trivedi, V. V. Shvartsman, D.C. Lupascu, M.S.A. Medeiros, R.C. Pullar, A.L.
M AN U
[1]
Kholkin, P. Zelenovskiy, A. Sosnovskikh, V.Y. Shur, Local manifestations of a static magnetoelectric effect in nanostructured BaTiO 3 –BaFe 12 O 9 composite multiferroics, Nanoscale. 7 (2015) 4489–4496. doi:10.1039/C4NR05657D. [2]
H. Yang, J. Zhang, Y. Lin, T. Wang, High Curie temperature and enhanced magnetoelectric properties of the laminated Li0.058(Na0.535K0.48)0.942NbO3/Co0.6
[3]
TE D
Zn0.4Fe1.7Mn0.3O4 composites, Sci. Rep. 7 (2017) 44855. doi:10.1038/srep44855. J. Jin, F. Zhao, K. Han, M.A. Haque, L. Dong, Q. Wang, Multiferroic polymer laminate composites exhibiting high magnetoelectric response induced by hydrogen-bonding interactions, Adv. Funct. Mater. 24 (2014) 1067–1073. doi:10.1002/adfm.201301675. S. Wohlrab, H. Du, M. Weiss, S. Kaskel, Foam-derived multiferroic BiFeO 3
EP
[4]
nanoparticles and integration into transparent polymer nanocomposites, J. Exp. Nanosci. 3
[5]
AC C
(2008) 1–15. doi:10.1080/17458080801935597. K. Mukhopadhyay, S. Sutradhar, S. Modak, S.K. Roy, P.K. Chakrabarti, Enhanced
Magnetic Behavior of Chemically Prepared Multiferroic Nanoparticles of GaFeO 3 in (GaFeO 3 ) 0.50 (Ni 0.4 Zn 0.4 Cu 0.2 Fe 2 O 4 ) 0.5 Nanocomposite, J. Phys. Chem. C. 116 (2012) 4948–4956. doi:10.1021/jp2065216.
[6]
D.P. Dutta, B.P. Mandal, M.D. Mukadam, S.M. Yusuf, A.K. Tyagi, Improved magnetic and ferroelectric properties of Sc and Ti codoped multiferroic nano BiFeO3 prepared via sonochemical synthesis, Dalt. Trans. 43 (2014) 7838. doi:10.1039/c3dt52779d.
[7]
J. Ma, J. Hu, Z. Li, C.W. Nan, Recent progress in multiferroic magnetoelectric
ACCEPTED MANUSCRIPT
composites: From bulk to thin films, Adv. Mater. 23 (2011) 1062–1087. doi:10.1002/adma.201003636. [8]
E.V. Ramana, F. Figueiras, M.P.F. Graça, M.A. Valente, Observation of magnetoelectric coupling and local piezoresponse in modified (Na0.5Bi0.5)TiO3–BaTiO3–CoFe2O4 lead-
[9]
RI PT
free composites, Dalt. Trans. 43 (2014) 9934. doi:10.1039/c4dt00956h.
B. Raneesh, K. Nandakumar, a. Saha, D. Das, H. Soumya, J. Philip, P. Sreekanth, R. Philip, Composition-structure–physical property relationship and nonlinear optical
12480–12487. doi:10.1039/C4RA12622J. [10]
SC
properties of multiferroic hexagonal ErMn 1−x Cr x O 3 nanoparticles, RSC Adv. 5 (2015) T. Woldu, B. Raneesh, M.V.R. Reddy, N. Kalarikkal, Grain size dependent
doi:10.1039/C5RA18018J. [11]
M AN U
magnetoelectric coupling of BaTiO 3 nanoparticles, RSC Adv. 6 (2016) 7886–7892. B. Raneesh, H. Soumya, J. Philip, S. Thomas, K. Nandakumar, Magnetoelectric properties of multiferroic composites (1−x)ErMnO3–xY3Fe5O12 at room temperature, J. Alloys Compd. 611 (2014) 381–385. doi:10.1016/j.jallcom.2014.05.155. [12]
D.K. Pradhan, V.S. Puli, S. Kumari, S. Sahoo, P.T. Das, K. Pradhan, D.K. Pradhan, J.F.
TE D
Scott, R.S. Katiyar, Studies of phase transitions and magnetoelectric coupling in PFNCZFO multiferroic composites, J. Phys. Chem. C. 120 (2016) 1936–1944. doi:10.1021/acs.jpcc.5b10422. [13]
J. Kreisel, M. Kenzelmann, Multiferroics - the challenge of coupling magnetism and
[14]
EP
ferroelectricity, Europhys. News. 40 (2009) 17–20. doi:10.1051/epn/2009702. W. Eerenstein, N.D. Mathur, J.F. Scott, Multiferroic and magnetoelectric materials,
[15]
AC C
Nature. 442 (2006) 759–765. doi:10.1038/nature05023. Z. Jian-Ping, L. Li, L. Qian, Z. Yu-Xiang, L. Peng, Hydrothermal synthesis and properties of NiFe2O4@BaTiO3 composites with well-matched interface, Sci. Technol. Adv. Mater. 13 (2012) 45001. doi:10.1088/1468-6996/13/4/045001.
[16]
M. Etier, V. V. Shvartsman, Y. Gao, J. Landers, H. Wende, D.C. Lupascu, Magnetoelectric Effect in (0–3) CoFe 2 O 4 -BaTiO 3 (20/80) Composite Ceramics Prepared by the Organosol Route, Ferroelectrics. 448 (2013) 77–85. doi:10.1080/00150193.2013.822292.
[17]
M. Etier, Y. Gao, V. V. Shvartsman, A. Elsukova, J. Landers, H. Wende, D.C. Lupascu,
ACCEPTED MANUSCRIPT
Cobalt Ferrite/Barium Titanate Core/Shell Nanoparticles, Ferroelectrics. 438 (2012) 115– 122. doi:10.1080/00150193.2012.743773. [18]
A.R. Abraham, B. Raneesh, T. Woldu, S. Aškrabić, S. Lazović, Z. Dohčević-Mitrović, O.S. Oluwafemi, S. Thomas, N. Kalarikkal, Realization of Enhanced Magnetoelectric
RI PT
Coupling and Raman Spectroscopic Signatures in 0–0 Type Hybrid Multiferroic Core– Shell Geometric Nanostructures, J. Phys. Chem. C. 121 (2017) 4352–4362. doi:10.1021/acs.jpcc.6b12461. [19]
T. Woldu, B. Raneesh, B.K. Hazra, S. Srinath, P. Saravanan, M.V.R. Reddy, N.
SC
Kalarikkal, A comparative study on structural, dielectric and multiferroic properties of CaFe2O4/BaTiO3 core-shell and mixed composites, J. Alloys Compd. 691 (2017) 644–
[20]
M AN U
652. doi:10.1016/j.jallcom.2016.08.277.
R. Sharma, V. Singh, R.K. Kotnala, R.P. Tandon, Investigation on the effect of ferrite content on the multiferroic properties of (1-x) Ba0.95Sr0.05TiO3 – (x) Ni0.7Zn0.2Co0.1Fe2O4 ceramic composite, Mater. Chem. Phys. 160 (2015) 447–455. doi:10.1016/j.matchemphys.2015.05.019.
[21]
P. Zachariasz, J. Kulawik, P. Guzdek, Preparation and characterization of the
TE D
microstructure, dielectric and magnetoelectric properties of multiferroic Sr3CuNb2O9– CoFe2O4 ceramics, Mater. Des. 86 (2015) 627–632. doi:10.1016/j.matdes.2015.07.062. [22]
Y. Yao, F. Lu, Y. Zhu, F. Wei, X. Liu, C. Lian, S. Wang, Magnetic core–shell CuFe2O4@C3N4 hybrids for visible light photocatalysis of Orange II, J. Hazard. Mater.
[23]
EP
297 (2015) 224–233. doi:10.1016/j.jhazmat.2015.04.046. M. Rawat, K.L. Yadav, Study of structural, electrical, magnetic and optical properties of
AC C
0.65BaTiO3–0.35Bi0.5Na0.5TiO3–BiFeO3 multiferroic composite, J. Alloys Compd. 597 (2014) 188–199. doi:10.1016/j.jallcom.2014.01.059.
[24]
R. Köferstein, T. Walther, D. Hesse, S.G. Ebbinghaus, Fine-grained BaTiO3–MgFe2O4
composites prepared by a Pechini-like process, J. Alloys Compd. 638 (2015) 141–147. doi:10.1016/j.jallcom.2015.03.082.
[25]
L.P. Curecheriu, M.T. Buscaglia, V. Buscaglia, L. Mitoseriu, P. Postolache, A. Ianculescu, P. Nanni, Functional properties of BaTiO3–Ni0.5Zn0.5Fe2O4 magnetoelectric ceramics prepared from powders with core-shell structure, J. Appl. Phys. 107 (2010) 104106. doi:10.1063/1.3340844.
ACCEPTED MANUSCRIPT
[26]
A. Chaudhuri, K. Mandal, Large magnetoelectric properties in CoFe2O4:BaTiO3 core– shell nanocomposites, J. Magn. Magn. Mater. 377 (2015) 441–445. doi:10.1016/j.jmmm.2014.10.142.
[27]
Y.S. Koo, T. Bonaedy, K.D. Sung, J.H. Jung, J.B. Yoon, Y.H. Jo, M.H. Jung, H.J. Lee,
RI PT
T.Y. Koo, Y.H. Jeong, Magnetodielectric coupling in core/shell BaTiO3⁄γ-Fe2O3 nanoparticles, Appl. Phys. Lett. 91 (2007) 212903. doi:10.1063/1.2817940. [28]
B.J. Evans, S.S. Hafner, Mössbauer resonance of Fe57 in oxidic spinels containing Cu and Fe, J. Phys. Chem. Solids. 29 (1968) 1573–1588. doi:10.1016/0022-3697(68)90100-5. J.Z. Jiang, G.F. Goya, H.R. Rechenberg, Magnetic properties of nanostructured CuFe 2 O
SC
[29]
4, J. Phys. Condens. Matter. 11 (1999) 4063–4078. doi:10.1088/0953-8984/11/20/313. I.P. Muthuselvam, R.N. Bhowmik, Structural phase stability and magnetism in Co2FeO4
M AN U
[30]
spinel oxide, Solid State Sci. 11 (2009) 719–725. doi:10.1016/j.solidstatesciences.2008.10.012. [31]
R. Zhang, M. Liu, L. Lu, S.-B. Mi, C.-L. Jia, H. Wang, High-performance CuFe 2 O 4 epitaxial thin films with enhanced ferromagnetic resonance properties, RSC Adv. 6 (2016) 100108–100114. doi:10.1039/C6RA22016A.
M.B. Smith, K. Page, T. Siegrist, P.L. Redmond, E.C. Walter, R. Seshadri, L.E. Brus,
TE D
[32]
M.L. Steigerwald, Crystal structure and the paraelectric-to-ferroelectric phase transition of nanoscale BaTiO3, J. Am. Chem. Soc. 130 (2008) 6955–6963. doi:10.1021/ja0758436. [33]
Y. Gao, A. Elsukova, D.C. Lupascu, Preparation of SiO2-encapsulated BaTiO3
EP
nanoparticles with tunable shell thickness by reverse microemulsion, Part. Part. Syst. Charact. 30 (2013) 832–836. doi:10.1002/ppsc.201300104. B. Luo, X. Wang, E. Tian, G. Li, L. Li, Electronic structure, optical and dielectric
AC C
[34]
properties of BaTiO 3 /CaTiO 3 /SrTiO 3 ferroelectric superlattices from first-principles calculations, J. Mater. Chem. C. 3 (2015) 8625–8633. doi:10.1039/C5TC01622C.
[35]
J. Cyriac, R.M. Thankachan, B. Raneesh, P.M.G. Nambissan, D. Sanyal, N. Kalarikkal, Positron annihilation spectroscopic studies of Mn substitution-induced cubic to tetragonal transformation in ZnFe2–xMnxO4 (x = 0.0–2.0) spinel nanocrystallites, Philos. Mag. 6435 (2015) 4000–4022. doi:10.1080/14786435.2015.1110631.
[36]
R.M. Thankachan, J. Cyriac, B. Raneesh, N. Kalarikkal, D. Sanyal, P.M.G. Nambissan, Cr 3+ -substitution induced structural reconfigurations in the nanocrystalline spinel
ACCEPTED MANUSCRIPT
compound ZnFe 2 O 4 as revealed from X-ray diffraction, positron annihilation and Mössbauer spectroscopic studies, RSC Adv. 5 (2015) 64966–64975. doi:10.1039/C5RA04516A. [37]
Z.Ž. Lazarević, M. Vijatović, Z. Dohčević-Mitrović, N.Ž. Romčević, M.J. Romčević, N.
RI PT
Paunović, B.D. Stojanović, The characterization of the barium titanate ceramic powders prepared by the Pechini type reaction route and mechanically assisted synthesis, J. Eur. Ceram. Soc. 30 (2010) 623–628. doi:10.1016/j.jeurceramsoc.2009.08.011. [38]
V. Vinothini, P. Singh, M. Balasubramanian, Synthesis of barium titanate nanopowder
doi:10.1016/j.ceramint.2004.12.012.
K. Raidongia, A. Nag, A. Sundaresan, C.N.R. Rao, Multiferroic and magnetoelectric
M AN U
[39]
SC
using polymeric precursor method, Ceram. Int. 32 (2006) 99–103.
properties of core-shell CoFe2O4@BaTiO3 nanocomposites, Appl. Phys. Lett. 97 (2010) 62904. doi:10.1063/1.3478231. [40]
V. Fridkin, S. Ducharme, Chapter 1: Ferroelectricity and ferroelectric phase transition, in: Ferroelectr. Nanoscale, 2014: pp. 1–9. doi:10.1007/978-3-642-41007-9.
[41]
J.S. Kim, C.W. Ahn, S.Y. Lee, A. Ullah, I.W. Kim, Effects of LiNbO3 substitution on
TE D
lead-free (K 0.5Na0.5)NbO3 ceramics: Enhanced ferroelectric and electrical properties, Curr. Appl. Phys. 11 (2011) S149–S153. doi:10.1016/j.cap.2011.03.049. [42]
A.S. Kumar, C.S.C. Lekha, S. Vivek, V. Saravanan, K. Nandakumar, S.S. Nair, Multiferroic and magnetoelectric properties of Ba0.85Ca0.15Zr0.1Ti0.9O3–CoFe2O4
EP
core–shell nanocomposite, J. Magn. Magn. Mater. 418 (2016) 294–299.
[43]
G. Singh, P.A. Kumar, C. Lundgren, A.T.J. van Helvoort, R. Mathieu, E. Wahlström,
[44]
AC C
doi:10.1016/j.jmmm.2016.02.065.
W.R. Glomm, Tunability in Crystallinity and Magnetic Properties of Core-Shell Fe Nanoparticles, Part. Part. Syst. Charact. 31 (2014) 1054–1059. doi:10.1002/ppsc.201400032.
A. Chaudhuri, K. Mandal, Large magnetoelectric properties in CoFe2O4:BaTiO3 core– shell nanocomposites, J. Magn. Magn. Mater. 377 (2015) 441–445. doi:10.1016/j.jmmm.2014.10.142.
[45]
D. Pal, M. Mandal, A. Chaudhuri, B. Das, D. Sarkar, K. Mandal, Micelles induced high coercivity in single domain cobalt-ferrite nanoparticles, J. Appl. Phys. 108 (2010) 124317.
ACCEPTED MANUSCRIPT
doi:10.1063/1.3525994. [46]
J. Shah, R.K. Kotnala, Induced magnetism and magnetoelectric coupling in ferroelectric BaTiO3 by Cr-doping synthesized by a facile chemical route, J. Mater. Chem. A. 1 (2013) 8601. doi:10.1039/c3ta11845b. a Srinivas, T. Bhimasankaram, An experimental setup for dynamic measurement of
RI PT
[47]
magnetoelectric effect, Bull. Mater. Sci. 21 (1998) 251–255. doi:10.1007/BF02744978. [48]
G. V. Duong, R. Groessinger, M. Schoenhart, D. Bueno-Basques, The lock-in technique for studying magnetoelectric effect, J. Magn. Magn. Mater. 316 (2007) 390–393.
[49]
SC
doi:10.1016/j.jmmm.2007.03.185.
C.A.F. Vaz, J. Hoffman, C.H. Ahn, R. Ramesh, Magnetoelectric coupling effects in
doi:10.1002/adma.200904326. [50]
M AN U
multiferroic complex oxide composite structures, Adv. Mater. 22 (2010) 2900–2918.
J.M. Rondinelli, M. Stengel, N.A. Spaldin, Carrier-mediated magnetoelectricity in complex oxide heterostructures, Nat. Nanotechnol. 3 (2008) 46–50. doi:10.1038/nnano.2007.412.
[51]
V. Corral-Flores, D. Bueno-Baques, D. Carrillo-Flores, J.A. Matutes-Aquino, Enhanced
TE D
magnetoelectric effect in core-shell particulate composites, J. Appl. Phys. 99 (2006) 2–5. doi:10.1063/1.2165147. [52]
D. Erdem, Y. Shi, F.J. Heiligtag, A.C. Kandemir, E. Tervoort, J.L.M. Rupp, M. Niederberger, Liquid-phase deposition of ferroelectrically switchable nanoparticle-based
EP
BaTiO 3 films of macroscopically controlled thickness, J. Mater. Chem. C. 3 (2015)
[53]
M.K. Mahata, T. Koppe, T. Mondal, C. Brüsewitz, K. Kumar, V. Kumar Rai, H. Hofsäss,
[54]
AC C
9833–9841. doi:10.1039/C5TC02214B.
U. Vetter, Incorporation of Zn 2+ ions into BaTiO 3 :Er 3+ /Yb 3+ nanophosphor: an effective way to enhance upconversion, defect luminescence and temperature sensing, Phys. Chem. Chem. Phys. 17 (2015) 20741–20753. doi:10.1039/C5CP01874A.
M. Singh, B.C. Yadav, A. Ranjan, M. Kaur, S.K. Gupta, Synthesis and characterization of
perovskite barium titanate thin film and its application as LPG sensor, Sensors Actuators B Chem. 241 (2017) 1170–1178. doi:10.1016/j.snb.2016.10.018. [55]
S. Ramakanth, K.C. James Raju, Band gap narrowing in BaTiO 3 nanoparticles facilitated by multiple mechanisms, J. Appl. Phys. 115 (2014) 173507. doi:10.1063/1.4871776.
ACCEPTED MANUSCRIPT
[56]
R.K. Selvan, V. Krishnan, C.O. Augustin, H. Bertagnolli, C.S. Kim, A. Gedanken, Investigations on the Structural, Morphological, Electrical, and Magnetic Properties of CuFe 2 O 4 −NiO Nanocomposites, Chem. Mater. 20 (2008) 429–439. doi:10.1021/cm701937q. Y. Yao, F. Lu, Y. Zhu, F. Wei, X. Liu, C. Lian, S. Wang, Magnetic core–shell
RI PT
[57]
CuFe2O4@C3N4 hybrids for visible light photocatalysis of Orange II, J. Hazard. Mater. 297 (2015) 224–233. doi:10.1016/j.jhazmat.2015.04.046. [58]
R. Köferstein, T. Walther, D. Hesse, S.G. Ebbinghaus, Crystallite-growth, phase
SC
transition, magnetic properties, and sintering behaviour of nano-CuFe2O4 powders prepared by a combustion-like process, J. Solid State Chem. 213 (2014) 57–64.
[59]
M AN U
doi:10.1016/j.jssc.2014.02.010.
R.K. Selvan, C.O. Augustin, V. Šepelák, L.J. Berchmans, C. Sanjeeviraja, A. Gedanken, Synthesis and characterization of CuFe2O4/CeO2 nanocomposites, Mater. Chem. Phys. 112 (2008) 373–380. doi:10.1016/j.matchemphys.2008.05.094.
[60]
K. Suzuki, K. Kijima, Optical Band Gap of Barium Titanate Nanoparticles Prepared by RF-plasma Chemical Vapor Deposition, Jpn. J. Appl. Phys. 44 (2005) 2081–2082.
[61]
TE D
doi:10.1143/JJAP.44.2081.
T. Woldu, B. Raneesh, P. Sreekanth, M. V. Ramana Reddy, R. Philip, N. Kalarikkal, Nonlinear optical properties of (1-x) CaFe2O4-xBaTiO3 composites, Ceram. Int. 42 (2016) 11093–11098. doi:10.1016/j.ceramint.2016.04.009. H. Mehrizadeh, A. Niaei, H.H. Tseng, D. Salari, A. Khataee, Synthesis of ZnFe2O4
EP
[62]
nanoparticles for photocatalytic removal of toluene from gas phase in the annular reactor,
AC C
J. Photochem. Photobiol. A Chem. 332 (2017) 188–195. doi:10.1016/j.jphotochem.2016.08.028.
[63]
A. Baykal, S. Güner, A. Demir, S. Esir, F. Genç, Effect of zinc substitution on magnetooptical properties of Mn1−xZnxFe2O4/SiO2 nanocomposites, Ceram. Int. 40 (2014) 13401–13408. doi:10.1016/j.ceramint.2014.05.059.
ACCEPTED MANUSCRIPT
HIGHLIGHTS CuFe2O4/BaTiO3 core-shell and mixed nanocomposites were successfully synthesized.
•
Ferroelectric, magnetic and magnetoelectric (ME) properties were confirmed.
•
Highest ME coupling coefficient has been noticed in the core-shell material.
AC C
EP
TE D
M AN U
SC
RI PT
•
S0925-8388(17)33371-6
DOI:
10.1016/j.jallcom.2017.09.309
Reference:
JALCOM 43365
To appear in:
Journal of Alloys and Compounds
Received Date: 13 June 2017 Revised Date:
28 August 2017
Accepted Date: 27 September 2017
Please cite this article as: R.M. Thankachan, B. Raneesh, A. Mayeen, S. Karthika, S. Vivek, S.S. Nair, S. Thomas, N. Kalarikkal, Room temperature magnetoelectric coupling effect in CuFe2O4/ BaTiO3 core-shell and mixed nanocomposites, Journal of Alloys and Compounds (2017), doi: 10.1016/ j.jallcom.2017.09.309. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
AC C
EP
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
ACCEPTED MANUSCRIPT
Room temperature magnetoelectric coupling effect in CuFe2O4/BaTiO3 core-shell and mixed nanocomposites Rahul Mundiyaniyil Thankachan1, B. Raneesh1*, Anshida Mayeen2, S. Karthika1, S. Vivek3,
RI PT
Swapna S. Nair3, Sabu Thomas4,5 and Nandakumar Kalarikkal2,5
Department of Physics, Catholicate College, Pathanamthitta, Kerala-689 645, India
2
School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam 686 560, India
3
Department of Physics, Central University of Kerala, Kasaragod 671 314, India
4
School of Chemical Sciences, Mahatma Gandhi University, Kottayam 686 560, India
5
International & Inter University Centre for Nanoscience and Nanotechnology, Mahatma Gandhi
*
M AN U
University, Kottayam, Kerala-686 560, India
SC
1
Corresponding author. E-mail address: [email protected]
Abstract
Novel magnetoelectric (ME) CuFe2O4@BaTiO3 core-shell and (1-x)BaTiO3-xCuFe2O4 (x=0.1,
TE D
0.3, 0.5, 0.7 and 0.9) mixed composites were prepared by two step sol-gel and a sol-gel followed by a solid state reaction respectively. Crystal structure and microstructure of the samples were examined using X-ray diffraction (XRD) and transmission electron microscopic (TEM) techniques. The ferroelectric and magnetic properties of the materials were confirmed by
EP
polarization versus electric field (P-E) and magnetization versus magnetic field (M-H) measurements respectively. To determine the coupling between ferroelectric and magnetic orderings, ME coupling studies were performed using a lock-in amplifier setup. The highest
AC C
value of the ME coupling coefficient (α) was noticed for the CuFe2O4@BaTiO3 core-shell (α = 22.5 mV cm-1 Oe-1) sample. Superior ME coupling behavior in the core-shell material is due to better connectivity between the ferroelectric and magnetic phases. The optical measurements indicate the possibility of easy manipulation of the band gap over a range of energies by mere control of the molar ratio of the phases. The smart architecture enables CuFe2O4@BaTiO3 sample to be a highly promising material for the design of devices based on ME multiferroics. Keywords: Multiferroic; core-shell; mixed nanocomposite; magnetoelectric coupling
ACCEPTED MANUSCRIPT
1. Introduction Magnetoelectric multiferroic (MF) materials are currently a main area of research due to its high technological significance in the modern civilization[1,2]. Possibility to manipulate the electrical
RI PT
property by a magnetic field and vice versa makes it an apt material for many demanding applications such as multiple-state memory elements, ME sensors, high-frequency filters, actuators and more[3–6]. From a technological perspective, a sizeable ME response at room temperature is necessary in order to utilize its full potential. Even though the ME response has been noticed as an intrinsic effect in single phase materials [7], the observed ME coupling in
SC
such a MF material is usually too feeble for an appropriate device performance[8]. During the past several years, some elegant strategies such as doping [9], particle size reduction [10] and
M AN U
ferroelectric-magnetic composite architecture [11] have been employed to develop the room temperature MF materials. As compared to single phase MF, composite MF material prepared by combining suitable ferroelectric and magnetic phases offers remarkable ME behavior [12]. In such an engineered MF material, ME coupling is an extrinsic property and may arise directly between the two order parameters, or indirectly via strain [13,14]. The ME properties in a composite MF material can be easily controlled by adjusting the volume fractions of the
TE D
individual phases[15]. In addition to the volume fractions and properties of the individual phases, the type of connectivity among the phases has a predominant effect on the ME coupling properties [16,17]. The composite ceramic MF materials synthesized by the conventional method (direct mechanical mixing of ferroelectric and magnetic phases) exhibited a weak ME effect
EP
mainly due to the low percolation threshold (~ 18%) in the magnetic phase[15]. Better intercalation and promising connectivity between the phases can be achieved by a core-shell
AC C
design consisting of a magnetic core and ferroelectric shell [18,19]. Several MF composites have been reported. Some of the composites that have been studied are (1-x)Ba0.95Sr0.05TiO3-(x)Ni0.7Zn0.2Co0.1Fe2O4 Ni0.5Zn0.5Fe2O4+Pb(Zr0.48Ti0.52)O3 BaTiO3−MgFe2O4
[24],
[22],
[20],
Sr3CuNb2O9–CoFe2O4
[21],
0.65BaTiO3–0.35Bi0.5Na0.5TiO3–BiFeO3
Ni0.5Zn0.5Fe2O4@BaTiO3
[25],
CoFe2O4@BaTiO3
[26]
[23], and
BaTiO3@Fe2O3 [27]. However, as far as the authors know there are no reports on the preparation and characterization of CuFe2O4/BaTiO3 core-shell and mixed nanocomposites MF systems. CuFe2O4 (CFO) has been selected as the magnetic phase because of its high saturation magnetization and high Neel temperature (TN=780±20 K)[28,29] and BaTiO3 (BTO) as the
ACCEPTED MANUSCRIPT
electrical counterpart due to its superior room temperature ferroelectric nature. Usually, most of the spinel ferrites exhibit cubic crystal structure[30]. But copper ferrite is a special candidate and can show cubic and tetragonal symmetries [31]. The crystallization of tetragonal crystal phase is favorable if the sample is slowly cooled from high temperatures[28,29]. The Curie temperature
RI PT
Tc reported for barium titanate is around 1300C. Above the Curie temperature, BTO undergoes a transition from its ferroelectric tetragonal phase to paraelectric cubic phase [32,33]. The ferroelectric polarization in the tetragonal crystal geometry of BTO is a result of the permanent electric dipole created by the displacement of titanium from the octahedron center to an off-
SC
center position[32,34]. In this paper, we present the results of the structural and morphological characterizations, electric, magnetic, magnetoelectric and optical studies of the novel CFO/BTO
M AN U
core-shell and mixed nanocomposite MF materials. 2. Experimental details 2.1 Materials
Cupric (III) nitrate trihydrate (Cu(NO3)2 · 3H2O), ferric (III) nitrate nonahydrate (Fe(NO₃)₃ . 9 H₂O) citric acid (C6H8O7) and ethylene glycol (C2H6O2) were purchased from Merck and used without further modification. Barium acetate (Ba(C2H3O2)2) titanium-tetra isopropoxide
2.2 Sample preparation
TE D
(Ti[OCH(CH3)]4) were purchased from Sigma Aldrich and used without further purification.
Preparation of CuFe2O4 nanoparticles: CuFe2O4 nanoparticles were synthesized by sol-gel
EP
method as described elsewhere[35,36]. At first, 0.2 M of cupric nitrate trihydrate and 0.4 M of ferric nitrate nonahydrate were dissolved in 100 mL double distilled water. To the solution, 5.24
AC C
g citric acid was added. The solution thus obtained was stirred for several hours and the homogeneous solution was maintained at 80 0C until a dried gel was formed. The dried gel was calcined at 800 0C for 5 h.
Preparation of BaTiO3 nanoparticles: BaTiO3 nanoparticles were prepared by the polymeric organometallic precursor method (Pechini method)[10,37]. Initially, separate citrate solutions of barium acetate and titanium tetra isopropoxide were prepared[38]. In the subsequent step, citrate solutions were mixed together and stirred at 90 0C. After the homogeneous mixing, the solution was maintained at 120 0C to promote polymerization and the removal of solvents. Finally, the dried gel was calcined at 800 0C for 5 h.
ACCEPTED MANUSCRIPT
Preparation of xCuFe2O4–(1-x)BaTiO3 mixed nanocomposites: The composite samples were prepared by mixing stoichiometric amounts of the CuFe2O4 and BaTiO3 phases using an agate mortar and pestle.
RI PT
Preparation of CuFe2O4@BaTiO3 core-shell nanoparticles: To obtain the CuFe2O4@BaTiO3 core-shell structure with 1:1 ratio of CuFe2O4 and BaTiO3 phases, 1.11 mL of titanium-tetra isopropoxide, 0.96 g barium acetate and 0.5 g citric acid were homogeneously mixed in a solvent composed of 25 mL water and 25 mL ethylene glycol. To the solution, 0.89 g of the prepared CuFe2O4 nanoparticles was uniformly dispersed by sonication. The solution was maintained at
SC
120 0C with continuous mechanical stirring. The dried gel thus obtained was calcined at 800 0C for 5 h [39]. The overall material preparation procedure of CuFe2O4@BaTiO3 core-shell sample
EP
TE D
M AN U
is schematically described in Fig. 1.
AC C
Fig. 1 Schematic illustration of the CuFe2O4@BaTiO3 core-shell material synthesis procedure. 2.3 Characterization
In this study, all the measurements were carried out at room temperature. XRD data were recorded over a range of 20-800 from the powder samples using Rigaku, MiniFlex 600 powder X-ray diffractometer with a Cu-Kα radiation source. The morphological images of the samples were captured by JEOL JEM 2100 transmission electron microscopy operating at 200 kV. Energy Dispersive X-ray (EDX) analysis was used to check the presence of various elements
ACCEPTED MANUSCRIPT
present in the sample. Ferroelectric loops were recorded by Marine India PE-01 loop tracer. Magnetic measurements were conducted using Versa lab, Quantum Design multifunctional vibrating sample magnetometer (VSM). To test the MF property, ME coupling measurements were carried out using lock-in amplifier ME coupling setup (Marine India). The linear optical
RI PT
studies of the samples were performed using Agilent Cary 5000 UV-Vis spectrophotometer in the wavelength range 200-800 nm. 3. Results and discussion
TE D
M AN U
SC
3.1. Structural analysis
composites.
EP
Fig. 2 XRD patterns of BTO, CFO, CFO@BTO core-shell and CFO-BTO (x=0.1 to 0.9) mixed
AC C
Fig. 2 shows the powder XRD patterns of the BTO, CFO, CFO@BTO core-shell and CFO-BTO (x=0.1 to 0.9) mixed composites. All the pronounced diffraction peaks of BTO can be indexed to a tetragonal crystal system (JCPDS 89-1428, space group P4mm) with lattice parameters of a=3.99
and c=4.03 . CFO diffraction peaks also belong to a tetragonal crystal structure
(JCPDS 34-0425, space group 141/amd) with lattice parameters of a=5.84
and c=8.63 . The
diffraction peaks at 22.13, 31.52, 38.91, 45.22, 50.91, 56.13, 65.82 and 70.43 are associated with the 001/100, 101/110, 111, 200, 201, 112/211, 202/220 and 212/300 reflections of BTO and the peaks at 29.95, 30.68, 34.55, 36.00, 37.23, 41.76, 43.81, 53.99, 55.10, 57.09, 58.10, 62.06 and
ACCEPTED MANUSCRIPT
64.13 represent the 112, 200, 103, 211, 202, 004, 220, 312, 105, 303, 321, 224 and 400 reflections of CFO, indicating the successful formation of the BTO and CFO crystal phases. According to the Scherrer equation[5], the average sizes of the primary crystallites were calculated to be 21 nm and 34 nm for BTO and CFO samples, respectively. The XRD diffraction
RI PT
patterns of the core-shell and the mixed composites show the characteristic peaks of the CFO and BTO phases. The intensity of the CFO peaks gets intensified with the increase of the CFO content in the mixed composites. The non-existence diffraction peaks other than tetragonal CFO and tetragonal BTO phases indicate the absence of impurities in the core-shell and mixed
SC
composites. 3.2. Morphological analysis
M AN U
Fig. 3(a) shows the TEM image of the 0.7CFO-0.3BTO mixed composite sample. It shows the agglomerated nanoparticles of the mixed composite. The corresponding high-resolution transmission electron microscopic (HRTEM) image of the 0.7CFO-0.3BTO mixed composite is shown in Fig. 3(b). The interplanar spacing of 0.28 nm in the HRTEM image represents the (101)/(110) plane of the BTO phase and the interplanar spacing of 0.249 nm corresponds to the (211) lattice plane of the CFO. The selected area electron diffraction (SAED) pattern shown in
AC C
EP
TE D
Fig. 3(c) points out the crystalline nature of the 0.7CFO-0.3BTO mixed composite.
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 3 (a) TEM image of 0.3BTO-0.7CFO mixed composite (b) corresponding HRTEM image and (c) SAED pattern.
EP
Fig. 4(a) and (b) show the TEM images of the CFO@BTO core-shell MF material under different magnifications. The core and shell structure of the CFO@BTO is clearly seen in the
AC C
Fig. 4(b). The diameter of the core calculated from the TEM image was 35.6 nm and the thickness of the shell was 31.7 nm. HRTEM image of the CFO@BTO core-shell (Fig. 4(c)) shows the well-defined lattice fringes of the core CFO and shell BTO and the calculated dspacing of the core (0.25 nm) and shell (0.28 nm) are in agreement with the d-spacing of (211) plane of the CFO and (110)/(101) plane of the BTO respectively. Furthermore, the SAED pattern shown in the inset of Fig. 4(c) indicates the crystallinity of the core-shell MF material.
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 4 (a) and (b) TEM images of CFO@BTO core-shell sample under different magnifications
EP
(c) corresponding HRTEM image, the inset represents the SAED pattern (d) the EDX spectrum.
To analyze the presence of various elements, EDX study was performed on the CFO@BTO
AC C
core-shell material. The EDX analysis (Fig. 4(d)) depicts only the peaks of copper, iron, barium, titanium and oxygen. This further confirms the purity of the synthesized CFO@BTO core-shell MF material.
3.3. Ferroelectric studies
P-E loops of the CFO-BTO mixed composites (x=0.1, 0.3, 0.5 and 0.7) and CFO@BTO coreshell have been recorded at a fixed frequency of 50 Hz and are shown in Fig. 5. The observed PE loops confirming the ferroelectric nature of the samples[40]. It is noticeable from the Fig. 5 that the ferroelectric loops are not saturated, a reason for such a behavior of the composite MF is the leakage current in the system due to the presence of the magnetic counterpart[41,42]. The
ACCEPTED MANUSCRIPT
measured values of the ferroelectric parameters such as maximum polarization (Pmax) and remnant polarization (Pr) from the P-E loops are listed in Table 1. The increase of the ferrite content reduces the availability of the ferroelectric nanoparticles as well as enhances the leakage current nature of the composite MF system. This combined effect resulted in the reduction of the
RI PT
maximum polarization value as noticed in Table 1. Even though the molar weight fractions of the ferroelectric and magnetic phases are equal in the CFO@BTO core-shell MF material, its maximum polarization value is close to the 0.1CFO-0.9BTO mixed composite sample. Since the ferroelectric phase is far more electrically insulating than the magnetic particles, such a coating
SC
isolate the conducting CFO particles from one another and effectively reduces the leakage current [15,19]. So the remarkable ferroelectric behavior noticed in the CFO@BTO core-shell
M AN U
sample can be attributed to the proper coating of the BTO phase over the magnetic core [19].
Table 1. Ferroelectric parameters of the CFO@BTO core-shell and CFO-BTO mixed composites.
Ferroelectric Parameters
Sample
0.610
TE D
CFO-BTO (x=0.1)
Pmax (µC/cm2)
Pr (µC/cm2)
0.113
0.372
0.065
CFO-BTO (x=0.5)
0.265
0.064
CFO-BTO (x=0.7)
0.195
0.083
CFO@BTO
0.594
0.101
AC C
EP
CFO-BTO (x=0.3)
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 5 PE loops of the CFO@BTO core-shell and CFO-BTO mixed composites (x=0.1, 0.3, 0.5 and 0.7).
3.4. Magnetic studies
TE D
To understand the magnetic nature of the CFO@BTO core-shell and CFO-BTO mixed composites, VSM measurements were carried out at room temperature and the curves thus obtained are shown in Fig. 6(a) and (b). Saturated M-H hysteresis loops have been noticed in all the samples studied, indicating the presence of magnetic ordering[43]. The magnetic parameters
EP
such as saturation magnetization (MS), remnant magnetization (Mr) and coercive field (Hr) are listed in Table 2. The Ms value of the composites increases from 2.39 emu/g to 28.36 emu/g with the increase of the CFO molar weight fraction from x=0.1 to 0.9. In the CFO@BTO core-shell
AC C
MF material, a saturation value of 17.87 emu/g has been noticed. It is evident from the Table 2 that coercivity of CFO@BTO is almost two fold higher than that of the CFO-BTO mixed composites. This may be due to the reduced movement of surface spins of the ferrite particles caused by the barium titanate coating[44,45]. So the high value of coercivity as observed in CFO@BTO can be taken into consideration to understand the better coating of ferroelectric material over the magnetic phase.
RI PT
ACCEPTED MANUSCRIPT
BTO mixed composites (b) low field region (±10 kOe).
SC
Figure 6 (a) Magnetization versus magnetic field curves of CFO@BTO core-shell and CFO-
M AN U
Table 2. Magnetic parameters of the CFO@BTO core-shell and CFO-BTO mixed composites. Magnetic Parameters
Sample
Ms (emu/g)
Mr (emu/g)
Hr (kOe)
2.39
1.15
0.70
CFO-BTO (x=0.3)
7.29
3.58
0.66
CFO-BTO (x=0.5)
12.24
5.96
0.59
CFO-BTO (x=0.7)
17.48
8.20
0.72
CFO-BTO (x=0.9)
28.36
10.94
0.73
CFO@BTO
17.87
8.95
1.35
EP
TE D
CFO-BTO (x=0.1)
3.5. Magnetoelectric studies
To check the interactions of magnetic and electric orders at the atomic level, the ME coupling
AC C
coefficients of the CFO-BTO mixed composites CFO@BTO core-shell have been determined by lock-in amplifier method[46,47]. A detailed description of the ME coupling experimental can be found elsewhere[11,46]. The variations of ME voltage with AC magnetic field of the CFO-BTO mixed composites and CFO@BTO core-shell are shown in Fig. 7(a). The measurements have been conducted by varying the AC magnetic field (frequency 850 Hz) from 0 to 80 Oe in the presence of a constant DC bias magnetic field (Hdc) of strength 2 kOe. The measured ME voltage shows a linear increase with the applied AC magnetic field and the linear ME coupling coefficient α, was calculated using the equation [21,26,48],
ACCEPTED MANUSCRIPT
α=dE/dH = (1/t)(dV/dH)=Vout/ht where Vout denotes the ME voltage generated across the sample surface, h represents the amplitude of the applied AC magnetic field, and t is the thickness of the sample. The obtained α values of the core-shell and mixed composites are listed in Table 3. The experimental results
RI PT
reveal that all the samples exhibit ME coupling at a DC magnetic bias of 2 kOe. Among the various mixed composites, highest α is noticed for the 0.7CFO-0.3BTO sample. However, CFO@BTO core-shell material exhibits α =22.5 mV cm-1 Oe-1 which is higher than that of the 0.7CFO-0.3BTO mixed composite sample. In case of multiphase MF materials, the coupling is
SC
expected to originate at the interface between the two dissimilar ferroic phases [49,50]. The improved mechanical coupling between ferroelectric and magnetic phases accounts for the high
M AN U
value of ME coupling evolved in the CFO@BTO core-shell material[51]. In the DC ME coupling measurements, generated ME voltage has been detected while varying the DC magnetic field from 0 to 5 kOe in the presence of an AC magnetic field of frequency 850 Hz and strength 10 Oe. The coupling coefficients of the various samples from the DC measurement have been found out by dividing the detected ME voltages by the AC magnetic field strength [46] and the curves thus obtained are shown in Fig. 7(b). The ME coupling coefficients of the samples shown
AC C
EP
TE D
in Fig. 7(b) are in agreement with the values listed in Table 3.
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 7 (a) Variation of ME voltage with AC magnetic field and (b) variation of ME coupling coefficient with DC magnetic field of CFO@BTO core-shell and CFO-BTO mixed composites.
EP
Table 3. ME coefficients of the CFO@BTO core-shell and CFO-BTO mixed composites. α (mV cm-1 Oe-1)
CFO-BTO (x=0.1)
5.15
AC C
Sample
CFO-BTO (x=0.3)
10.31
CFO-BTO (x=0.5)
12.93
CFO-BTO (x=0.7)
15.63
CFO-BTO (x=0.9)
14.66
CFO@BTO
22.50
ACCEPTED MANUSCRIPT
3.6. Linear optical studies Band gap energy is a characteristic feature of all the materials and can be estimated using a UVvisible spectroscopic technique. The band gaps of the materials in the present study were determined by assuming as direct type [23,52–59] and calculated using Tauc’s law, (αhʋ)2 = hʋ-
RI PT
Eg, where h is the Planck constant, α the linear absorption coefficient and Eg is the band gap energy[60,61]. For the band gap calculation, we have plotted (αhʋ)2 against hʋ and are shown in Fig. 8. The linear portion of the curve characterizes the fundamental absorption property of the material[53]. The band gap values were determined by extrapolating the linear portion of (αhʋ)2
SC
versus hʋ plot to the point (αhν)2 =0[62,63]. The Eg value of the CFO, BTO, CFO-BTO mixed composites and CFO@BTO core-shell are shown in Table 4. The obtained band gaps of CFO
M AN U
and BTO are in agreement with the values from previous reports [23,52–59]. The band gap energy of the mixed composite decreases with the increase of CFO content. This could be due to
AC C
EP
TE D
the less band gap value of the CFO as compared to BTO.
Fig. 8 (αhν)2 versus hν plots of BTO, CFO, CFO@BTO core-shell and CFO-BTO mixed composites.
ACCEPTED MANUSCRIPT
Table 4 The band gap value of BTO, CFO, CFO@BTO core-shell and CFO-BTO mixed composites. Sample
Band Gap
CFO-BTO(x= 0.1)
3.22
CFO-BTO (x=0.3)
3.16
CFO-BTO (x=0.5)
3.07
CFO-BTO (x-0.7)
2.85
CFO-BTO (x=0.9)
2.21
CFO@BTO
2.40
CFO
4. Conclusions
SC
3.25
M AN U
BTO
RI PT
Eg (eV)
1.9
CuFe2O4@BaTiO3 core-shell and xCuFe2O4–(1-x)BaTiO3 mixed nanocomposites were synthesized. Successful formation of the BTO and CFO crystal phases were verified in all the
TE D
samples by XRD analysis. The morphological character of the x=0.7 mixed composite and CFO@BTO core-shell were analyzed through TEM imaging. Ferroelectric properties of the CFO-BTO mixed composites were decreased with the increase of CFO molar weight fraction from x=0.1 to 0.9 but consequently, it induced high saturation magnetism. The proper coating of
EP
the BTO shell on the CFO phase causes a reduction of the leakage current in the CFO@BTO core-shell sample and thereby it exhibited ferroelectric parameters close to the x=0.1 mixed
AC C
composite sample. A high saturation magnetization of 17.87 emu/g has been perceived in the CFO@BTO core-shell material and the envisaged high coercivity explains the better interaction of the CFO and the BTO phases. Room temperature ME coupling was observed in all the CFOBTO mixed composites but the coupling coefficient noticed in the CFO@BTO core-shell was higher than that of the CFO-BTO mixed composites. The enhancement in the ME coupling coefficient as observed in the core-shell MF sample is a direct consequence of the improved connectivity between the BTO-ferroelectric and CFO-magnetic phases. UV-Vis characterizations suggest the feasibility of band gap tuning over a range of energies by controlling the molar ratio
ACCEPTED MANUSCRIPT
of the CFO and the BTO phases. It is believed that this work will be highly useful for the design of ultra-modern devices based on magnetoelectric multiferroics.
Acknowledgements
RI PT
The authors acknowledge the financial support from SERB - Govt. of India through ECR project scheme (ECR/2015/000536). Authors also acknowledge the use of X-ray diffraction facilities at St. Thomas College, Palai, India. The authors thank Mr. Anu A S for the TEM imaging and EDX
SC
analysis and Dr. Praveen G for UV-Vis measurements.
References
H. Trivedi, V. V. Shvartsman, D.C. Lupascu, M.S.A. Medeiros, R.C. Pullar, A.L.
M AN U
[1]
Kholkin, P. Zelenovskiy, A. Sosnovskikh, V.Y. Shur, Local manifestations of a static magnetoelectric effect in nanostructured BaTiO 3 –BaFe 12 O 9 composite multiferroics, Nanoscale. 7 (2015) 4489–4496. doi:10.1039/C4NR05657D. [2]
H. Yang, J. Zhang, Y. Lin, T. Wang, High Curie temperature and enhanced magnetoelectric properties of the laminated Li0.058(Na0.535K0.48)0.942NbO3/Co0.6
[3]
TE D
Zn0.4Fe1.7Mn0.3O4 composites, Sci. Rep. 7 (2017) 44855. doi:10.1038/srep44855. J. Jin, F. Zhao, K. Han, M.A. Haque, L. Dong, Q. Wang, Multiferroic polymer laminate composites exhibiting high magnetoelectric response induced by hydrogen-bonding interactions, Adv. Funct. Mater. 24 (2014) 1067–1073. doi:10.1002/adfm.201301675. S. Wohlrab, H. Du, M. Weiss, S. Kaskel, Foam-derived multiferroic BiFeO 3
EP
[4]
nanoparticles and integration into transparent polymer nanocomposites, J. Exp. Nanosci. 3
[5]
AC C
(2008) 1–15. doi:10.1080/17458080801935597. K. Mukhopadhyay, S. Sutradhar, S. Modak, S.K. Roy, P.K. Chakrabarti, Enhanced
Magnetic Behavior of Chemically Prepared Multiferroic Nanoparticles of GaFeO 3 in (GaFeO 3 ) 0.50 (Ni 0.4 Zn 0.4 Cu 0.2 Fe 2 O 4 ) 0.5 Nanocomposite, J. Phys. Chem. C. 116 (2012) 4948–4956. doi:10.1021/jp2065216.
[6]
D.P. Dutta, B.P. Mandal, M.D. Mukadam, S.M. Yusuf, A.K. Tyagi, Improved magnetic and ferroelectric properties of Sc and Ti codoped multiferroic nano BiFeO3 prepared via sonochemical synthesis, Dalt. Trans. 43 (2014) 7838. doi:10.1039/c3dt52779d.
[7]
J. Ma, J. Hu, Z. Li, C.W. Nan, Recent progress in multiferroic magnetoelectric
ACCEPTED MANUSCRIPT
composites: From bulk to thin films, Adv. Mater. 23 (2011) 1062–1087. doi:10.1002/adma.201003636. [8]
E.V. Ramana, F. Figueiras, M.P.F. Graça, M.A. Valente, Observation of magnetoelectric coupling and local piezoresponse in modified (Na0.5Bi0.5)TiO3–BaTiO3–CoFe2O4 lead-
[9]
RI PT
free composites, Dalt. Trans. 43 (2014) 9934. doi:10.1039/c4dt00956h.
B. Raneesh, K. Nandakumar, a. Saha, D. Das, H. Soumya, J. Philip, P. Sreekanth, R. Philip, Composition-structure–physical property relationship and nonlinear optical
12480–12487. doi:10.1039/C4RA12622J. [10]
SC
properties of multiferroic hexagonal ErMn 1−x Cr x O 3 nanoparticles, RSC Adv. 5 (2015) T. Woldu, B. Raneesh, M.V.R. Reddy, N. Kalarikkal, Grain size dependent
doi:10.1039/C5RA18018J. [11]
M AN U
magnetoelectric coupling of BaTiO 3 nanoparticles, RSC Adv. 6 (2016) 7886–7892. B. Raneesh, H. Soumya, J. Philip, S. Thomas, K. Nandakumar, Magnetoelectric properties of multiferroic composites (1−x)ErMnO3–xY3Fe5O12 at room temperature, J. Alloys Compd. 611 (2014) 381–385. doi:10.1016/j.jallcom.2014.05.155. [12]
D.K. Pradhan, V.S. Puli, S. Kumari, S. Sahoo, P.T. Das, K. Pradhan, D.K. Pradhan, J.F.
TE D
Scott, R.S. Katiyar, Studies of phase transitions and magnetoelectric coupling in PFNCZFO multiferroic composites, J. Phys. Chem. C. 120 (2016) 1936–1944. doi:10.1021/acs.jpcc.5b10422. [13]
J. Kreisel, M. Kenzelmann, Multiferroics - the challenge of coupling magnetism and
[14]
EP
ferroelectricity, Europhys. News. 40 (2009) 17–20. doi:10.1051/epn/2009702. W. Eerenstein, N.D. Mathur, J.F. Scott, Multiferroic and magnetoelectric materials,
[15]
AC C
Nature. 442 (2006) 759–765. doi:10.1038/nature05023. Z. Jian-Ping, L. Li, L. Qian, Z. Yu-Xiang, L. Peng, Hydrothermal synthesis and properties of NiFe2O4@BaTiO3 composites with well-matched interface, Sci. Technol. Adv. Mater. 13 (2012) 45001. doi:10.1088/1468-6996/13/4/045001.
[16]
M. Etier, V. V. Shvartsman, Y. Gao, J. Landers, H. Wende, D.C. Lupascu, Magnetoelectric Effect in (0–3) CoFe 2 O 4 -BaTiO 3 (20/80) Composite Ceramics Prepared by the Organosol Route, Ferroelectrics. 448 (2013) 77–85. doi:10.1080/00150193.2013.822292.
[17]
M. Etier, Y. Gao, V. V. Shvartsman, A. Elsukova, J. Landers, H. Wende, D.C. Lupascu,
ACCEPTED MANUSCRIPT
Cobalt Ferrite/Barium Titanate Core/Shell Nanoparticles, Ferroelectrics. 438 (2012) 115– 122. doi:10.1080/00150193.2012.743773. [18]
A.R. Abraham, B. Raneesh, T. Woldu, S. Aškrabić, S. Lazović, Z. Dohčević-Mitrović, O.S. Oluwafemi, S. Thomas, N. Kalarikkal, Realization of Enhanced Magnetoelectric
RI PT
Coupling and Raman Spectroscopic Signatures in 0–0 Type Hybrid Multiferroic Core– Shell Geometric Nanostructures, J. Phys. Chem. C. 121 (2017) 4352–4362. doi:10.1021/acs.jpcc.6b12461. [19]
T. Woldu, B. Raneesh, B.K. Hazra, S. Srinath, P. Saravanan, M.V.R. Reddy, N.
SC
Kalarikkal, A comparative study on structural, dielectric and multiferroic properties of CaFe2O4/BaTiO3 core-shell and mixed composites, J. Alloys Compd. 691 (2017) 644–
[20]
M AN U
652. doi:10.1016/j.jallcom.2016.08.277.
R. Sharma, V. Singh, R.K. Kotnala, R.P. Tandon, Investigation on the effect of ferrite content on the multiferroic properties of (1-x) Ba0.95Sr0.05TiO3 – (x) Ni0.7Zn0.2Co0.1Fe2O4 ceramic composite, Mater. Chem. Phys. 160 (2015) 447–455. doi:10.1016/j.matchemphys.2015.05.019.
[21]
P. Zachariasz, J. Kulawik, P. Guzdek, Preparation and characterization of the
TE D
microstructure, dielectric and magnetoelectric properties of multiferroic Sr3CuNb2O9– CoFe2O4 ceramics, Mater. Des. 86 (2015) 627–632. doi:10.1016/j.matdes.2015.07.062. [22]
Y. Yao, F. Lu, Y. Zhu, F. Wei, X. Liu, C. Lian, S. Wang, Magnetic core–shell CuFe2O4@C3N4 hybrids for visible light photocatalysis of Orange II, J. Hazard. Mater.
[23]
EP
297 (2015) 224–233. doi:10.1016/j.jhazmat.2015.04.046. M. Rawat, K.L. Yadav, Study of structural, electrical, magnetic and optical properties of
AC C
0.65BaTiO3–0.35Bi0.5Na0.5TiO3–BiFeO3 multiferroic composite, J. Alloys Compd. 597 (2014) 188–199. doi:10.1016/j.jallcom.2014.01.059.
[24]
R. Köferstein, T. Walther, D. Hesse, S.G. Ebbinghaus, Fine-grained BaTiO3–MgFe2O4
composites prepared by a Pechini-like process, J. Alloys Compd. 638 (2015) 141–147. doi:10.1016/j.jallcom.2015.03.082.
[25]
L.P. Curecheriu, M.T. Buscaglia, V. Buscaglia, L. Mitoseriu, P. Postolache, A. Ianculescu, P. Nanni, Functional properties of BaTiO3–Ni0.5Zn0.5Fe2O4 magnetoelectric ceramics prepared from powders with core-shell structure, J. Appl. Phys. 107 (2010) 104106. doi:10.1063/1.3340844.
ACCEPTED MANUSCRIPT
[26]
A. Chaudhuri, K. Mandal, Large magnetoelectric properties in CoFe2O4:BaTiO3 core– shell nanocomposites, J. Magn. Magn. Mater. 377 (2015) 441–445. doi:10.1016/j.jmmm.2014.10.142.
[27]
Y.S. Koo, T. Bonaedy, K.D. Sung, J.H. Jung, J.B. Yoon, Y.H. Jo, M.H. Jung, H.J. Lee,
RI PT
T.Y. Koo, Y.H. Jeong, Magnetodielectric coupling in core/shell BaTiO3⁄γ-Fe2O3 nanoparticles, Appl. Phys. Lett. 91 (2007) 212903. doi:10.1063/1.2817940. [28]
B.J. Evans, S.S. Hafner, Mössbauer resonance of Fe57 in oxidic spinels containing Cu and Fe, J. Phys. Chem. Solids. 29 (1968) 1573–1588. doi:10.1016/0022-3697(68)90100-5. J.Z. Jiang, G.F. Goya, H.R. Rechenberg, Magnetic properties of nanostructured CuFe 2 O
SC
[29]
4, J. Phys. Condens. Matter. 11 (1999) 4063–4078. doi:10.1088/0953-8984/11/20/313. I.P. Muthuselvam, R.N. Bhowmik, Structural phase stability and magnetism in Co2FeO4
M AN U
[30]
spinel oxide, Solid State Sci. 11 (2009) 719–725. doi:10.1016/j.solidstatesciences.2008.10.012. [31]
R. Zhang, M. Liu, L. Lu, S.-B. Mi, C.-L. Jia, H. Wang, High-performance CuFe 2 O 4 epitaxial thin films with enhanced ferromagnetic resonance properties, RSC Adv. 6 (2016) 100108–100114. doi:10.1039/C6RA22016A.
M.B. Smith, K. Page, T. Siegrist, P.L. Redmond, E.C. Walter, R. Seshadri, L.E. Brus,
TE D
[32]
M.L. Steigerwald, Crystal structure and the paraelectric-to-ferroelectric phase transition of nanoscale BaTiO3, J. Am. Chem. Soc. 130 (2008) 6955–6963. doi:10.1021/ja0758436. [33]
Y. Gao, A. Elsukova, D.C. Lupascu, Preparation of SiO2-encapsulated BaTiO3
EP
nanoparticles with tunable shell thickness by reverse microemulsion, Part. Part. Syst. Charact. 30 (2013) 832–836. doi:10.1002/ppsc.201300104. B. Luo, X. Wang, E. Tian, G. Li, L. Li, Electronic structure, optical and dielectric
AC C
[34]
properties of BaTiO 3 /CaTiO 3 /SrTiO 3 ferroelectric superlattices from first-principles calculations, J. Mater. Chem. C. 3 (2015) 8625–8633. doi:10.1039/C5TC01622C.
[35]
J. Cyriac, R.M. Thankachan, B. Raneesh, P.M.G. Nambissan, D. Sanyal, N. Kalarikkal, Positron annihilation spectroscopic studies of Mn substitution-induced cubic to tetragonal transformation in ZnFe2–xMnxO4 (x = 0.0–2.0) spinel nanocrystallites, Philos. Mag. 6435 (2015) 4000–4022. doi:10.1080/14786435.2015.1110631.
[36]
R.M. Thankachan, J. Cyriac, B. Raneesh, N. Kalarikkal, D. Sanyal, P.M.G. Nambissan, Cr 3+ -substitution induced structural reconfigurations in the nanocrystalline spinel
ACCEPTED MANUSCRIPT
compound ZnFe 2 O 4 as revealed from X-ray diffraction, positron annihilation and Mössbauer spectroscopic studies, RSC Adv. 5 (2015) 64966–64975. doi:10.1039/C5RA04516A. [37]
Z.Ž. Lazarević, M. Vijatović, Z. Dohčević-Mitrović, N.Ž. Romčević, M.J. Romčević, N.
RI PT
Paunović, B.D. Stojanović, The characterization of the barium titanate ceramic powders prepared by the Pechini type reaction route and mechanically assisted synthesis, J. Eur. Ceram. Soc. 30 (2010) 623–628. doi:10.1016/j.jeurceramsoc.2009.08.011. [38]
V. Vinothini, P. Singh, M. Balasubramanian, Synthesis of barium titanate nanopowder
doi:10.1016/j.ceramint.2004.12.012.
K. Raidongia, A. Nag, A. Sundaresan, C.N.R. Rao, Multiferroic and magnetoelectric
M AN U
[39]
SC
using polymeric precursor method, Ceram. Int. 32 (2006) 99–103.
properties of core-shell CoFe2O4@BaTiO3 nanocomposites, Appl. Phys. Lett. 97 (2010) 62904. doi:10.1063/1.3478231. [40]
V. Fridkin, S. Ducharme, Chapter 1: Ferroelectricity and ferroelectric phase transition, in: Ferroelectr. Nanoscale, 2014: pp. 1–9. doi:10.1007/978-3-642-41007-9.
[41]
J.S. Kim, C.W. Ahn, S.Y. Lee, A. Ullah, I.W. Kim, Effects of LiNbO3 substitution on
TE D
lead-free (K 0.5Na0.5)NbO3 ceramics: Enhanced ferroelectric and electrical properties, Curr. Appl. Phys. 11 (2011) S149–S153. doi:10.1016/j.cap.2011.03.049. [42]
A.S. Kumar, C.S.C. Lekha, S. Vivek, V. Saravanan, K. Nandakumar, S.S. Nair, Multiferroic and magnetoelectric properties of Ba0.85Ca0.15Zr0.1Ti0.9O3–CoFe2O4
EP
core–shell nanocomposite, J. Magn. Magn. Mater. 418 (2016) 294–299.
[43]
G. Singh, P.A. Kumar, C. Lundgren, A.T.J. van Helvoort, R. Mathieu, E. Wahlström,
[44]
AC C
doi:10.1016/j.jmmm.2016.02.065.
W.R. Glomm, Tunability in Crystallinity and Magnetic Properties of Core-Shell Fe Nanoparticles, Part. Part. Syst. Charact. 31 (2014) 1054–1059. doi:10.1002/ppsc.201400032.
A. Chaudhuri, K. Mandal, Large magnetoelectric properties in CoFe2O4:BaTiO3 core– shell nanocomposites, J. Magn. Magn. Mater. 377 (2015) 441–445. doi:10.1016/j.jmmm.2014.10.142.
[45]
D. Pal, M. Mandal, A. Chaudhuri, B. Das, D. Sarkar, K. Mandal, Micelles induced high coercivity in single domain cobalt-ferrite nanoparticles, J. Appl. Phys. 108 (2010) 124317.
ACCEPTED MANUSCRIPT
doi:10.1063/1.3525994. [46]
J. Shah, R.K. Kotnala, Induced magnetism and magnetoelectric coupling in ferroelectric BaTiO3 by Cr-doping synthesized by a facile chemical route, J. Mater. Chem. A. 1 (2013) 8601. doi:10.1039/c3ta11845b. a Srinivas, T. Bhimasankaram, An experimental setup for dynamic measurement of
RI PT
[47]
magnetoelectric effect, Bull. Mater. Sci. 21 (1998) 251–255. doi:10.1007/BF02744978. [48]
G. V. Duong, R. Groessinger, M. Schoenhart, D. Bueno-Basques, The lock-in technique for studying magnetoelectric effect, J. Magn. Magn. Mater. 316 (2007) 390–393.
[49]
SC
doi:10.1016/j.jmmm.2007.03.185.
C.A.F. Vaz, J. Hoffman, C.H. Ahn, R. Ramesh, Magnetoelectric coupling effects in
doi:10.1002/adma.200904326. [50]
M AN U
multiferroic complex oxide composite structures, Adv. Mater. 22 (2010) 2900–2918.
J.M. Rondinelli, M. Stengel, N.A. Spaldin, Carrier-mediated magnetoelectricity in complex oxide heterostructures, Nat. Nanotechnol. 3 (2008) 46–50. doi:10.1038/nnano.2007.412.
[51]
V. Corral-Flores, D. Bueno-Baques, D. Carrillo-Flores, J.A. Matutes-Aquino, Enhanced
TE D
magnetoelectric effect in core-shell particulate composites, J. Appl. Phys. 99 (2006) 2–5. doi:10.1063/1.2165147. [52]
D. Erdem, Y. Shi, F.J. Heiligtag, A.C. Kandemir, E. Tervoort, J.L.M. Rupp, M. Niederberger, Liquid-phase deposition of ferroelectrically switchable nanoparticle-based
EP
BaTiO 3 films of macroscopically controlled thickness, J. Mater. Chem. C. 3 (2015)
[53]
M.K. Mahata, T. Koppe, T. Mondal, C. Brüsewitz, K. Kumar, V. Kumar Rai, H. Hofsäss,
[54]
AC C
9833–9841. doi:10.1039/C5TC02214B.
U. Vetter, Incorporation of Zn 2+ ions into BaTiO 3 :Er 3+ /Yb 3+ nanophosphor: an effective way to enhance upconversion, defect luminescence and temperature sensing, Phys. Chem. Chem. Phys. 17 (2015) 20741–20753. doi:10.1039/C5CP01874A.
M. Singh, B.C. Yadav, A. Ranjan, M. Kaur, S.K. Gupta, Synthesis and characterization of
perovskite barium titanate thin film and its application as LPG sensor, Sensors Actuators B Chem. 241 (2017) 1170–1178. doi:10.1016/j.snb.2016.10.018. [55]
S. Ramakanth, K.C. James Raju, Band gap narrowing in BaTiO 3 nanoparticles facilitated by multiple mechanisms, J. Appl. Phys. 115 (2014) 173507. doi:10.1063/1.4871776.
ACCEPTED MANUSCRIPT
[56]
R.K. Selvan, V. Krishnan, C.O. Augustin, H. Bertagnolli, C.S. Kim, A. Gedanken, Investigations on the Structural, Morphological, Electrical, and Magnetic Properties of CuFe 2 O 4 −NiO Nanocomposites, Chem. Mater. 20 (2008) 429–439. doi:10.1021/cm701937q. Y. Yao, F. Lu, Y. Zhu, F. Wei, X. Liu, C. Lian, S. Wang, Magnetic core–shell
RI PT
[57]
CuFe2O4@C3N4 hybrids for visible light photocatalysis of Orange II, J. Hazard. Mater. 297 (2015) 224–233. doi:10.1016/j.jhazmat.2015.04.046. [58]
R. Köferstein, T. Walther, D. Hesse, S.G. Ebbinghaus, Crystallite-growth, phase
SC
transition, magnetic properties, and sintering behaviour of nano-CuFe2O4 powders prepared by a combustion-like process, J. Solid State Chem. 213 (2014) 57–64.
[59]
M AN U
doi:10.1016/j.jssc.2014.02.010.
R.K. Selvan, C.O. Augustin, V. Šepelák, L.J. Berchmans, C. Sanjeeviraja, A. Gedanken, Synthesis and characterization of CuFe2O4/CeO2 nanocomposites, Mater. Chem. Phys. 112 (2008) 373–380. doi:10.1016/j.matchemphys.2008.05.094.
[60]
K. Suzuki, K. Kijima, Optical Band Gap of Barium Titanate Nanoparticles Prepared by RF-plasma Chemical Vapor Deposition, Jpn. J. Appl. Phys. 44 (2005) 2081–2082.
[61]
TE D
doi:10.1143/JJAP.44.2081.
T. Woldu, B. Raneesh, P. Sreekanth, M. V. Ramana Reddy, R. Philip, N. Kalarikkal, Nonlinear optical properties of (1-x) CaFe2O4-xBaTiO3 composites, Ceram. Int. 42 (2016) 11093–11098. doi:10.1016/j.ceramint.2016.04.009. H. Mehrizadeh, A. Niaei, H.H. Tseng, D. Salari, A. Khataee, Synthesis of ZnFe2O4
EP
[62]
nanoparticles for photocatalytic removal of toluene from gas phase in the annular reactor,
AC C
J. Photochem. Photobiol. A Chem. 332 (2017) 188–195. doi:10.1016/j.jphotochem.2016.08.028.
[63]
A. Baykal, S. Güner, A. Demir, S. Esir, F. Genç, Effect of zinc substitution on magnetooptical properties of Mn1−xZnxFe2O4/SiO2 nanocomposites, Ceram. Int. 40 (2014) 13401–13408. doi:10.1016/j.ceramint.2014.05.059.
ACCEPTED MANUSCRIPT
HIGHLIGHTS CuFe2O4/BaTiO3 core-shell and mixed nanocomposites were successfully synthesized.
•
Ferroelectric, magnetic and magnetoelectric (ME) properties were confirmed.
•
Highest ME coupling coefficient has been noticed in the core-shell material.
AC C
EP
TE D
M AN U
SC
RI PT
•