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Effect of Zn doping on structural, magnetic and optical properties of cobalt ferrite nanoparticles synthesized via. Co-precipitation method
Journal Pre-proof Effect of Zn doping on structural, magnetic and optical properties of cobalt ferrite nanoparticles synthesized via. Co-precipitation method
Deepali D. Andhare, Supriya R. Patade, Jitendra S. Kounsalye, K.M. Jadhav PII:
S0921-4526(20)30065-X
DOI:
https://doi.org/10.1016/j.physb.2020.412051
Reference:
PHYSB 412051
To appear in:
Physica B: Physics of Condensed Matter
Received Date:
28 November 2019
Accepted Date:
27 January 2020
Please cite this article as: Deepali D. Andhare, Supriya R. Patade, Jitendra S. Kounsalye, K.M. Jadhav, Effect of Zn doping on structural, magnetic and optical properties of cobalt ferrite nanoparticles synthesized via. Co-precipitation method, Physica B: Physics of Condensed Matter (2020), https://doi.org/10.1016/j.physb.2020.412051
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Journal Pre-proof Effect of Zn doping on structural, magnetic and optical properties of cobalt ferrite nanoparticles synthesized via. Co-precipitation method Deepali D. Andharea, Supriya R. Patadea, Jitendra S. Kounsalyea,b, K. M. Jadhava* aDepartment
of Physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad – 431004, Maharashtra, India
bDepartment
of Physics, Late Rajkamalji Bharti Arts, Commerce and Smt. S. R. Bharati
Science College, Arni, Yavatmal – 445103, Maharashtra, India *Corresponding
Author: [email protected]
ABSTRACT In the present work, Co1-xZnxFe2O4 (x=0.0, 0.3, 0.5, 0.7 and 1.0) nanoparticles were prepared by chemical co-precipitation method. Prepared Co1-xZnxFe2O4 ferrite powder was sintered at 900ºC for 4h after TG-DTA thermal studies. XRD analysis revealed the single-phase cubic structure of Co-Zn ferrite nanoparticles and also studied the variation in structural parameter with increasing Zn concentration. The formation of the ferrite phase was confirmed by studying FTIR spectra. The SEM images shows the agglomeration of spherical grains due to the difference in the magnetic nature of the sample. Peaks of respective elements (Co, Zn, Fe, and O) in EDX spectra show the formation of cobalt zinc ferrite. Variation of energy band gap with increasing zinc concentration in cobalt ferrite studied by UV-Vis. Spectroscopy. The M-H loops revealed that the values of magnetic parameters such as MS, Mr, Hc, nB, and Mr/Ms ratio decrease with increasing Zn2+ content in cobalt ferrite nanoparticles. Keywords: Cobalt zinc ferrite nanoparticles; Chemical co-precipitation; Optical; Magnetization.
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Journal Pre-proof 1. Introduction In recent years, the use of magnetic nanoparticles has been a vastly increased in biomedical applications. Many researchers have been focused on the improvement of magnetic nanoparticles (MNPs) as well as to improve their applicability in different areas. Investigation of ferrite nanoparticles is very much interested due to their enhanced magnetic and electrical properties [1-3]. Most of the applications such as Magnetic Resonance Imaging (MRI), Magnetic Hyperthermia, drug delivery, biosensors and bioimaging are depends on the magnetic properties such as spin canting effect, superparamagnetism and spin-glass-like behaviour of the magnetic nanoparticles [4-7]. Among the various magnetic nanoparticles spinel ferrite shows excellent optical, electrical, structural and magnetic properties [8]. Spinel ferrite has general formula MFe2O4 (M=Zn, Co, Mn, Ni, Cu, etc.) have many applications in various field, such as biotechnology, catalysis, energy storage device, information storage system, ferrofluid technology, and electronic circuits [9-13]. M. Rahimi et. al. successfully prepared PVA coated Ni0.3Zn0.7Fe2O4 nanoparticles by a solgel auto-combustion method and calculated crystallite size, as well as magnetization, were in the range 17-24nm and 16-19 emu/g respectively [14]. S. Munjal et.al. Synthesized the oleic acid-coated water-dispersible CoFe2O4 nanoparticles by hydrothermal method with improved colloidal stability and also studied its applications in the biomedical field [15]. Rautet. al. synthesized the Zn substituted CoFe2O4 nanoparticles by the sol-gel auto-combustion method and reported the particle size was increased from 45-49nm [16]. Among the various spinel ferrites, cobalt ferrite is an important magnetic metal oxide because of its high coercivity, large magnetostrictive coefficient, and moderate saturation magnetization. The CoFe2O4 has an inverse spinel structure but when divalent metal ions such as Zn, Cd, Ni, etc. are doped in cobalt ferrite, it changes the structure of cobalt ferrite from inverse spinel to normal spinel ferrites[17]. Cobalt ferrite is the hard magnetic material and zinc ferrite is soft but the substitution of Zn2+ ion in cobalt ferrite reduces its hardness. Zinc substituted cobalt ferrites (CoxZn1-xFe2O4) is one of the soft magnetic material having good chemical stability, high coercivity and highly sensitive to temperature [18]. Cobalt ferrite is generally known for its high coercivity and saturation magnetization but the substitution of non-magnetic zinc ion altered its magnetic property from ferromagnetic to superparamagnetic [19]. Magnetic material with superparamagnetic behaviour has huge applications in biomedical science.
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Journal Pre-proof M. Ben Ali et. al. successfully prepared Co-Zn ferrites nanoparticles by the Sol-Gel method and average particle size was increased from 11nm-28nm [20]. M. Madhukara Naik et. al. reported that the Zn1-xCoxFe2O4 nanoparticles prepared by the combustion method and calculated particle size are in the range 21nm-12nm [21]. Magnetic nanoparticles are synthesized by various synthesis techniques such as sol-gel auto-combustion, microemulsion, hydrothermal technique, and forced hydrolysis method [22]. But the coprecipitation method is broadly used for the synthesis of spinel ferrite nanoparticles due to its number of good points like it is a time-consuming method, cost-effective, simple to do and reliable, etc. [23]. The chemical co-precipitation method produces a homogeneous powder with maximum yield and does not require any organic fuels like citric acid etc. Thus, in the present study, we have synthesized Co1-xZnxFe2O4 with x value 0, 0.3, 0.5, 0.7, and 1 nanoparticles by co-precipitation method. Aim of the present work is to study the effect of Zn substitution on thermal, structural, magnetic, optical, morphological and elemental properties of Co-Zn ferrite nanoparticles investigated by TG-DTA, XRD, VSM, UV-Vis. Spectroscopy, SEM, and EDX respectively. 2. Experimental 2.1. Materials and methods Co1-xZnxFe2O4 ferrite nanoparticles with x=0.0, 0.3, 0.5, 0.7 and 1 were synthesized by the co-precipitation method. Analytical grade cobalt chloride hexahydrate (CoCl2.6H2O), zinc chloride (ZnCl2), ferric chloride (FeCl3) and sodium hydroxide (NaOH) were used as raw materials. Nanoparticles prepared by co-precipitating aqueous solutions of CoCl2.6H2O, ZnCl2, and FeCl3. Initially, the solutions of CoCl2.6H2O, ZnCl2, and FeCl3 were mixed in their respective stoichiometric amounts (7 ml of 1M CoCl2.6H2O, 3 ml of 1M ZnCl2 and 10 ml of 1M FeCl3 in case of Co0.7Zn0.3Fe2O4 and similarly for the other values of x) at room temperature with constant stirring for 30 min. 1M NaOH was added drop-wise into the solution, to adjust pH at 11. The solution was heated at 80°C under constant stirring. After 2 hours constant stirring and heating ageing process were completed. The solution was cooled down to room temperature under stirring that the nanoparticles set to the bottom of the beaker. The solution was washed to separate out substance from precipitated solution with acetone or hot DI-water to extract traces of water and sodium chloride respectively. Then, the precipitate was settled down by using centrifugal separator after washing with acetone. The nanoparticles were dried at room temperature for 48 h. The as-prepared Co1-xZnxFe2O4 spinel 3
Journal Pre-proof ferrite powder was ground for 40 minutes and the thermal stability of the prepared sample was measured by TG-DTA up to 1200 ºC. Hence, samples sintered at 900 oC for 4 h in the furnace. Prepared powder samples were characterized by different characterization techniques. 2.2. Characterizations To study the change in mass of the sample and decomposition mechanism of Co1-xZnxFe2O4 ferrite sample as the function of temperature was investigated by TG-DTA (Shimazdu DTA60H) technique. Thermal analysis (TG-DTA) was carried out under a nitrogen atmosphere and temperature varying from 23ºC to 1200ºC. The structural properties of prepared samples of Co1-xZnxFe2O4 (x=0, 0.3, 0.5, 0.7, and 1) ferrites were studied by recording the X-ray diffraction (XRD) diffraction pattern at room temperature. The powder form of samples was characterized by using X-ray diffractometer (Bruker) with Cu Kα (λ=1.5406Å) radiation, operated at 20 mA current and 40 kV voltage. The XRD pattern was recorded in the 2θ range of 20° ˃ 2θ ˃ 80°. The analysis of the functional group was carried out from FTIR spectra. FT-IR spectra of prepared nanoparticles were recorded on Shimazdu FTIR spectrometer at room temperature within the wavenumber range 400cm-1 to 2000 cm-1. The light absorption spectrum in the UV-Visible range 200nm to 800nm was recorded using UV-Vis. Spectroscopy to estimate the variation of optical bandgap with increasing Zn content. By using UV-Visible analysis, the optical bandgap (Eg) was calculated by the following equation; ∝ 𝐸𝑝 = 𝐴(𝐸𝑝 ― 𝐸𝑔)𝑞 Where, is the absorption coefficient, Ep is the photon energy, A is a constant and q depends on transition nature. The surface structure of all prepared samples was examined by SEM through JEOL (JSM-5600) and the elemental concentration distribution was carried out by EDX. Magnetic measurements of all prepared samples were recorded by using VSM (Quantum Design–Modular control system) at below room temperature that is at 5K with an applied ± 30 kOe magnetic field.
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Journal Pre-proof 3. Results and discussion 3.1. Thermo - Gravimetric and Differential Thermal Analysis (TG-DTA) TG-DTA was performed under a nitrogen atmosphere in such a way that temperature varies from 23ºC to 1200ºC with heating rate 20ºC/min. According to TG–DT analysis it is clear that the removal of water, decomposition of metal hydroxide and formation of spinel ferrite can be completed below 900ºC temperature[24]. Three different weight losses exhibit in the TGA curve and DTA curve shows two endothermic and one exothermic peak corresponding to each weight loss[25]. First weight loss (10%) and first endothermic peak (at 90ºC) arises due to the ejection of moisture which is in the 30ºC-400ºC temperature range. Second weight loss (4%) and exothermic peak (at 427ºC) is in 400ºC-827ºC temperature range shows the decomposition of metal hydroxide. Third weight loss (3%) and second endothermic peak (at 875ºC) is in the temperature range 827ºC-900ºC indicates the formation of spinel ferrite. Total weight loss in all three samples is about 17%. Therefore, prepared nanoparticles were sintered at 900 ºC for 4h.
Fig.1 TG-DTA curve of Co1-xZnxFe2O4 ferrite nanoparticles.
3.2. X-ray Diffraction (XRD) Figure 2 shows XRD patterns of Co1-xZnxFe2O4 (x=0, 0.3, 0.5, 0.7, and 1) nanoparticles. XRD patterns of all samples reveal that the presence of reflection planes having (h k l) values as (220), (311), (222), (400), (422), (511), (440), (620), and (533) indicates the cubic spinel structure for all the sample with exhibition of Fd-3m space group, which is confirmed by JCPDS card no. 221086 (for cobalt ferrite, when x=0) and 891012 (for zinc ferrite, when x=1). It is evident from JCPDS values that angles corresponding to zinc ferrite (values of 2θ = 35.27, 62.225, 56.671) are lower than cobalt ferrite (values of 2θ = 35.437, 30.084, 62.585, 56.973). From figure 2 it is clear that the corresponding peak positions are shifted towards 5
Journal Pre-proof lower angle with the substitution of Zn content in the cobalt ferrite matrix. No any additional peak related to impurity observed in pattern indicates that high purity of the prepared samples. The position (2θ) of the XRD peaks and their FWHM are used to estimate the lattice parameter with the following equation [26], sin2 𝜃 = (𝜆2 𝑎2)(ℎ2 + 𝑘2 + 𝑙2) Where a is the lattice parameter, θ is the diffraction angle, λ is the wavelength of the X-ray and h, k, l are miller indices of each plane family. The lattice parameter was found in the range 8.3737 Å -8.4303 Å. The value of the lattice parameter increases with increasing zinc concentration this is probably due to the difference in ionic radius of Co2+ (0.72 Å) and Zn2+ (0.74 Å). The crystallite size of all prepared samples was calculated by using DebyeScherrerʼs equation[27] 𝑡=
𝑘𝜆 (𝛽𝑐𝑜𝑠𝜃)
Where t is the crystallite size of the particles, λ is the X-ray wavelength, k is a constant (value of k is 0.9), θ is the angle of diffraction and β is the full width at half maximum (FWHM). Particles size of the prepared samples was obtained between 12 nm to 17 nm which increases with the concentration of zinc. The X-ray density was calculated by using the formula[28] 𝑑𝑥 = 8𝑀 (𝑁𝐴𝑎3) Where dx is X-ray density, M molecular weight of the composition, NA is the Avogadro′s number and ʽaʼis the lattice parameter. X-ray density was varying from 5.3079 g/cm3 to 5.3447 g/cm3 with a concentration of zinc. Using Archimedes principle bulk density (dB) of all samples was measured which is observed to decreases from 3.638 g/cm3to 3.488 g/cm3 with an increasing concentration of zinc in Co-Zn ferrite nanoparticles. Porosity (P%) of the sample was calculated using the values of dx and dB, which is increased from 31.46% to 34.73% as the value of zinc concentration (i.e. x=0, 0.3, 0.5, 0.7, and 1) increases in Co-Zn ferrite nanoparticles. The variation in crystallite size, the lattice constant, X-ray density, Bulk density and porosity with respect to increasing zinc concentration in cobalt ferrite is shown in table 1.
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Fig.2. XRD pattern of Co1-xZnxFe2O4( x=0, 0.3, 0.5, 0.7 and 1)
Table 1 Variation of lattice constant ʽaʼ (Å), Crystallite size ʽtʼ (nm), X-ray density ʽdxʼ (g/cm3), Bulk density ʽdBʼ(g/cm3), Porosity (%), lattice volume (Å3) of Co1-xZnxFe2O4 (x=0, 0.3, 0.5, 0.7, 1) spinel ferrite nanoparticles. Composition
a (Å)
t (nm)
dX(g/cm3)
dB(g/cm3)
P (%)
V (Å3)
CoFe2O4
8.3737
12
5.3079
3.638
31.46
589.2
Co0.7Zn0.3Fe2O4
8.3940
13
5.3129
3.617
31.91
591.4
Co0.5Zn0.5Fe2O4
8.4080
15
5.3153
3.587
32.52
594.4
Co0.3Zn0.7Fe2O4
8.4200
16
5.3213
3.537
33.53
596.9
ZnFe2O4
8.4303
17
5.3447
3.488
34.73
599.1
3.3. Fourier - Transform Infrared Spectroscopy (FT-IR) The FT-IR spectra of prepared Co-Zn nanoparticles were carried out in the range of 400 2000 cm-1 at room temperature for the identification of chemical bonds present in the sample and ensures the formation of the ferrite phase. Two main absorption peaks in FTIR spectra indicate the intrinsic stretching-vibrations of oxygen with metal which is the characteristic of spinel ferrite[29]. FT-IR spectra of Co1-xZnxFe2O4 (x=0, 0.3, 0.5, 0.7, 1) ferrite samples show in figure 3. The first band (ʋ1) observed with the higher wavenumber in the range 533-550 cm-1 corresponds to the stretching vibrations of the M-O at the tetrahedral site. The other band (ʋ2) with the lower wavenumber appeared around 392-396 7
Journal Pre-proof cm-1 is attributed to the octahedral metal-oxygen stretching[20]. The band positions of all samples are shown in table 2. The frequency band shifted with the variation in zinc concentration, this may be due to Co, Zn and Fe cations redistribution on both sites. Ferrite phase formation of all samples was confirmed by analyzing attribute peaks in FTIR spectra.
Fig.3. FTIR Spectra for Co1-xZnxFe2O4 (x=0, 0.3, 0.5, 0.7 and 1).
Table 2. Comparison of the main FTIR transmittance bands for Co1-xZnxFe2O4 with x = 0, 0.3, 0.5, 0.7 and 1.s Composition
ʋ1 (cm-1)
ʋ2 (cm-1)
CoFe2O4
533.76
396.43
Co0.7Zn0.3Fe2O4
536.92
396.56
Co0.5Zn0.5Fe2O4
545.70
398.79
Co0.3Zn0.7Fe2O4
548.84
398.02
ZnFe2O4
550.68
399.86
3.4. UV-Vis. Spectroscopy Study The optical properties of the samples Co1-xZnxFe2O4 (x= 0, 0.3, 0.5, 0.7, and 1) nanoparticles were investigated by UV-Vis spectroscopy. A spectrometer in the photon wavelength range 200-800nm shown in figure 4. The absorbance normally depends on a number of factors such as impurity centers, grain size, bandgap, lattice parameter, and surface roughness[30]. The absorption spectra are shown in figure 4a. From figure 4a clearly show that there is no visible 8
Journal Pre-proof absorption observed. The absorption spectra indicate the higher absorption peak shifted towards higher wavelength with increasing zinc concentration, this shift indicates that the change in optical bandgap due to the effect of quantum confinement. The absorption coefficient of nanoparticles was calculated by the equation[31] ∝=
2.303 × 𝐴 𝑡
Where, is the absorption coefficient, A is absorbance and t is the thickness of the sample. The optical bandgap of samples was calculated by using the Tauc plot. The energy band gap of Co-Zn spinel ferrite nanoparticles was calculated by using allowed direct bandgap expression given below[32]; 1
𝛼ℎ𝜗 = 𝐴(ℎ𝜗 ― 𝐸𝑔)
2
Were, Eg is bandgap A is constant, is absorption coefficient, hυ is photon energy. The hυ versus (αhυ) 2 plot for all samples shown in figure 4b optical band gap values are calculated from intercept made by the extrapolating liner part of the curve. The energy band gap decreases from 2.8306 eV to 2.258 eV with increasing Zn concentration in Cobalt ferrite shown in table 3. The decrease in bandgap with an increase in particle size can be attributed to Brassʼs model. According to this model energy bandgap associated with particle size by the relation; ℏ2𝜋2 1 𝑚𝑒
+ 2𝑒𝑟2 𝐸𝑔 = 𝐸𝑏𝑢𝑙𝑘 𝑔
(
1
)
1.8𝑒2
+ 𝑚ℎ ― 4𝜋𝜀𝜀 ⃘𝑟
Where Eg is the bandgap, Egbulk is the bulk energy gap, ℏ is equal to h/2𝝅, r is the particle size, me is the effective mass of electrons, mh is the effective mass of holes, ε is the relative permittivity, ε0 is the permittivity of free space, and e is charge of electrons. A similar explanation was also repeated in the literature [33, 34]. Hence energy band gap affected by increasing crystallite size and lattice constant.
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Fig.4. UV-Vis. Spectra of Co1-xZnxFe2O4 (x= 0, 0.3, 0.5, 0.7, and 1) nanoparticles
Table 3 Bandgap energy of Co1-xZnxFe2O4 (x= 0, 0.3, 0.5, 0.7, and 1) nanoparticles Composition
CoFe2O4
Co0.7Zn0.3Fe2O4
Co0.5Zn0.5Fe2O4
Co0.3Zn0.7Fe2O4
ZnFe2O4
Band gap (eV)
2.830
2.566
2.447
2.326
2.258
3.5. SEM/EDX analysis The morphology of prepared Co1-xZnxFe2O4 (x=0, 0.3, 0.5, 0.7, 1) nanoparticles was observed by scanning electron microscopy (SEM). The SEM images of particles shown in figure 5 at 1μm scale. SEM images substantiate the formation of nanocrystalline grain having spherical nature and showed higher agglomeration. The agglomeration occurred due to magnetic dipole-dipole interaction, this interaction decreases with increasing zinc concentration in the cobalt ferrite nanoparticles[19]. The magnetization of cobalt ferrite is higher than zinc ferrite hence, doping of zinc in cobalt ferrite causes a decrease in magnetization it resulted that the attractive force in nanoparticles goes on decreasing. So the agglomeration depends on the concentration of zinc in cobalt ferrite nanoparticles shown in the SEM image. The elemental composition of samples Co1-xZnxFe2O4 (x=0, 0.3, 0.5, 0.7, 1) was carried out by Energy-dispersive X-ray spectroscopy(EDX). Figure 5 shows EDX spectra for all zinc substituted cobalt ferrite nanoparticles, which clearly indicates the presence of Co, Zn, O and Fe elemental peaks. No, any other elemental peak was observed in the EDX spectrum which indicated the purity of the sample. Elemental compositions of all elements present in the 10
Journal Pre-proof prepared samples are shown in Table 4 this result indicates that the obtained atomic ratio of all elements (Co, Zn, O, and Fe) was well-matched with the expected stoichiometric proportion of elements in synthesized nanoparticles.
Fig.5. SEM with EDX image of the Co1-xZnxFe2O4 sample (a)x=0, (b)x=0.3, (c)x=0.5, (d)x=0.7 and (e)x=1
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Journal Pre-proof Table 4 The elemental composition of synthesized Co1-xZnxFe2O4 (x=0.0, 0.3, 0.5, 0.7, and 1) Composition
at%
CoFe2O4
Co 15.94
Zn -
Fe 27.70
O 57.36
Co0.7Zn0.3Fe2O4
10.80
4.51
28.72
56.97
Co0.5Zn0.5Fe2O4
7.65
7.07
28.14
57.61
Co0.3Zn0.7Fe2O4
4.91
10.06
28.08
57.65
-
14.28
28.58
57.90
ZnFe2O4
3.6. Magnetic properties Magnetic properties of synthesized Co1-xZnxFe2O4 (x=0, 0.3, 0.5, 0.7 and 1) nanoparticles were characterized by VSM at 5K temperature with an applied magnetic field 30000 Oe. Figure 6 shows the M-H loop of prepared samples. The values of various magnetic parameters of samples such as MS, Mr, Hc, Mr/Ms ratio, and nB measured from the M-H plots are listed in Table 5. Magnetic properties of spinel ferrite depend on the particle size, cation distribution, and doping. In the case of spinel ferrite cobalt ferrite shows hard magnetic behaviour as compared to Zinc ferrite[35]. Zn2+ ions have zero magnetic moments. The substitution of Zn2+ ions at tetrahedral (A) site replaces magnetic Fe3+ ions which causes decrease magnetic moment at A-site. The higher concentration of Fe3+ and Co2+ magnetic ions at B-site leads to enhance B-B exchange interaction and weakening of A-B interaction[36]. The weakening of A-B magnetic interaction decreases due to diamagnetic zinc substitution. As a result of zinc substitution, magnetic properties of cobalt ferrite decreased[37]. The different magnetic parameters were calculated from M-H plots, the saturation magnetization decreases from 60 emu/g to 43 emu/g, remanence magnetization decreases from 43 emu/g to 29 emu/g and coercivity decreases from 3309 Oe to 1630 Oe with increasing Zn concentration this variation was explained graphically in figure 6. From the M-H plot, it is clear that all samples reveal ferromagnetic nature but magnetization decreases with increasing Zn2+ ions. The variation in magneton number ‘nB’ is related to A-B interaction and it was calculated using the relation, 𝑛𝐵 =
[𝑀𝑠 × 𝑀𝑤 ]
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Fig.6. Magnetization hysteresis loop of Co1-xZnxFe2O4nanoparticlesand variation of Ms(emu/g) and Hc(Oe) with Zn concentration calculated at low temperature (5K) temperature.
Were, MS is saturation magnetization; MW is the molecular weight of the composition. Magneton numbers (nB) sharply decreases from 2.5469 μB to 1.8883 μB when the value of x is varied from 0.0 to 1.0. The Squareness ratio that is the ratio of remanence magnetization with saturation magnetization (Mr/Ms) of all prepared samples was observed decreasing from 0.7177 to 0.6668 with increasing concentration of zinc from 0.0 to 1.0 in cobalt ferrite. This study confirms the magnetization or magnetic properties decreases with increasing Zn concentration maybe because of the non-magnetic nature of zinc, due to particle size effect or due to exchanging A-B interaction[38]. Table 5 The values of magnetic parameters calculated from M-H loops observed at 5K of Co1xZnxFe2O4
nanoparticles.
Composition
Ms (emu/g)
Mr (emu/g)
Hc (Oe)
Mr/Ms
nB (μB)
CoFe2O4
60.63
43.52
3309
0.7177
2.5469
Co0.7Zn0.3Fe2O4
56.66
41.03
2680
0.7241
2.3997
Co0.5Zn0.5Fe2O4
50.14
33.39
2226
0.6659
2.1351
Co0.3Zn0.7Fe2O4
48.84
32.11
1639
0.6575
2.0911
ZnFe2O4
43.75
29.24
1630
0.6683
1.8883
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Journal Pre-proof 4. Conclusion Co1-xZnxFe2O4 ferrite nanoparticles with x value 0.0, 0.3, 0.5, 0.7 and 1were successfully synthesized by co-precipitation method. Co1-xZnxFe2O4 (x=0, 0.3, 0.5, 0.7, and 1) nanoparticles possess single-phase cubic spinel structure was confirmed by XRD analysis. The crystallite size increases with increase Zn substitution in prepared samples were observed from the XRD study. Structural parameters such as lattice constant and X-ray density increase with increasing zinc concentration. Two main absorption peaks near 400 cm-1 and 600 cm-1 observed in FTIR spectra which confirmed the ferrite nature of the sample. SEM image shows the spherical nature of grains and the agglomeration decreases with increasing zinc concentration. The stoichiometric proportion of elements present in prepared samples was confirmed by EDX spectra. The energy band gap of prepared samples calculated from the Tauc plot increases from 2.258 eV to 2.8306 eV with increasing Zn concentration. Hysteresis loop of ZnFe2O4 is very small as compared to CoFe2O4 which concluded that the zinc ferrite is soft magnetic material than cobalt ferrite. From the present study, it can be concluded that with increasing substitution of Zn2+ in cobalt ferrite magnetic properties go on decreases. Acknowledgements The Author (Miss. Deepali D. Andhare) is thankful to Dr. V. Ganesan, Ex-centre director of UGC-DAE consortium for scientific research, Indore, India for providing UV-Vis spectroscopy measurement facilities. Authors are grateful to Dr. Alok Banerjee center director of UGC-DAE consortium for scientific research, Indore, India for providing vibrating sample magnetometer (VSM) measurement facilities and also thankful to Dr. D. M. Phase and Dr. V. K. Ahire scientist UGC-DAE consortium for scientific research, Indore, India for providing SEM and EDAX measurement facility. Conflict of Interest No conflict of interest. References 1.
Gordani, G.R., A. Ghasemi, and A. Saidi, Enhanced magnetic properties of substituted Sr-hexaferrite nanoparticles synthesized by co-precipitation method. Ceramics International, 2014. 40(3): p. 4945-4952.
14
Journal Pre-proof 2.
Kahn, M.L. and Z.J. Zhang, Synthesis and magnetic properties of CoFe 2 O 4 spinel ferrite nanoparticles doped with lanthanide ions. Applied Physics Letters, 2001. 78(23): p. 3651-3653.
3.
Bharati, V., et al., Influence of trivalent Al–Cr co-substitution on the structural, morphological and Mössbauer properties of nickel ferrite nanoparticles. Journal of Alloys and Compounds, 2019: p. 153501.
4.
Somvanshi, S.B., et al. Investigations of structural, magnetic and induction heating properties of surface functionalized zinc ferrite nanoparticles for hyperthermia applications. in AIP Conference Proceedings. 2019. AIP Publishing.
5.
Somvanshi, S.B., et al., Hydrophobic to hydrophilic surface transformation of nanoscale zinc ferrite via oleic acid coating: magnetic hyperthermia study towards biomedical applications. Ceramics International, 2019.
6.
Patade, S.R., et al., Preparation and Characterizations of Magnetic Nanofluid of Zinc Ferrite for Hyperthermia Application. Nanomaterials and Energy, 2020: p. 1-7.
7.
Kale, S.B., et al. Enhancement in surface area and magnetization of CoFe2O4 nanoparticles for targeted drug delivery application. in AIP Conference Proceedings. 2018. AIP Publishing LLC.
8.
Somvanshi, S.B., et al., Influential diamagnetic magnesium (Mg2+) ion substitution in nano-spinel zinc ferrite (ZnFe2O4): Thermal, structural, spectral, optical and physisorption analysis. Ceramics International, 2019.
9.
Alone, S., et al., Chemical synthesis, structural and magnetic properties of nanostructured Co–Zn–Fe–Cr ferrite. Journal of Alloys and Compounds, 2011. 509(16): p. 5055-5060.
10.
Kharat, P.B., et al. Temperature dependent viscosity of cobalt ferrite/ethylene glycol ferrofluids. in AIP Conference Proceedings. 2018. AIP Publishing LLC.
11.
Kharat, P.B., et al., Exploration of thermoacoustics behavior of water based nickel ferrite nanofluids by ultrasonic velocity method. Journal of Materials Science: Materials in Electronics, 2019. 30(7): p. 6564-6574.
12.
Borade, R.M., et al., Spinel zinc ferrite nanoparticles: an active nanocatalyst for microwave irradiated solvent free synthesis of chalcones. Materials Research Express, 2020.
13.
Babrekar, M. and K. Jadhav, Synthesis and characterization of spray deposited lithium ferrite thin film. Int. Res. J. Sci. Eng. Special, 2017(A1): p. 73-76.
15
Journal Pre-proof 14.
Rahimi, M., et al., The effect of polyvinyl alcohol (PVA) coating on structural, magnetic properties and spin dynamics of Ni0. 3Zn0. 7Fe2O4 ferrite nanoparticles. Journal of Magnetism and Magnetic Materials, 2013. 347: p. 139-145.
15.
Munjal, S., et al., Water dispersible CoFe2O4 nanoparticles with improved colloidal stability for biomedical applications. Journal of Magnetism and Magnetic Materials, 2016. 404: p. 166-169.
16.
Raut, A., et al., Synthesis, structural investigation and magnetic properties of Zn2+ substituted cobalt ferrite nanoparticles prepared by the sol–gel auto-combustion technique. Journal of Magnetism and Magnetic Materials, 2014. 358: p. 87-92.
17.
Coppola, P., et al., Hydrothermal synthesis of mixed zinc–cobalt ferrite nanoparticles: structural and magnetic properties. Journal of Nanoparticle Research, 2016. 18(5): p. 138.
18.
Hossain, M., Study of the Magnetic and Transport Properties of Ytterbium Doped CoZn Ferrites. 2018, Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh.
19.
Topkaya, R., A. Baykal, and A. Demir, Yafet–Kittel-type magnetic order in Znsubstituted cobalt ferrite nanoparticles with uniaxial anisotropy. Journal of nanoparticle research, 2013. 15(1): p. 1359.
20.
Ali, M.B., et al., Effect of zinc concentration on the structural and magnetic properties of mixed Co–Zn ferrites nanoparticles synthesized by sol/gel method. Journal of Magnetism and Magnetic Materials, 2016. 398: p. 20-25.
21.
Naik, M.M., et al., Green synthesis of zinc doped cobalt ferrite nanoparticles: Structural, optical, photocatalytic and antibacterial studies. Nano-Structures & NanoObjects, 2019. 19: p. 100322.
22.
Yadav, R.S., et al., Magnetic properties of Co1− xZnxFe2O4 spinel ferrite nanoparticles synthesized by starch-assisted sol–gel autocombustion method and its ball milling. Journal of Magnetism and Magnetic Materials, 2015. 378: p. 190-199.
23.
Amri, A., et al., Developments in the synthesis of flat plate solar selective absorber materials via sol–gel methods: a review. Renewable and Sustainable Energy Reviews, 2014. 36: p. 316-328.
24.
Bardhan, A., et al., Low temperature synthesis of zinc ferrite nanoparticles. Solid State Sciences, 2010. 12(5): p. 839-844.
25.
Tianshu, Z., et al., Ethanol-sensing characteristics of cadmium ferrite prepared by chemical coprecipitation. Materials Chemistry and Physics, 1999. 61(3): p. 192-198. 16
Journal Pre-proof 26.
O’Donnell, M., et al., Structural analysis of a series of strontium-substituted apatites. Acta Biomaterialia, 2008. 4(5): p. 1455-1464.
27.
Yan, H., et al., Influences of different synthesis conditions on properties of Fe3O4 nanoparticles. Materials Chemistry and Physics, 2009. 113(1): p. 46-52.
28.
Bradley, A.J. and u.A. Taylor, An X-ray analysis of the nickel-aluminium system. Proceedings of the Royal Society of London. Series A-Mathematical and Physical Sciences, 1937. 159(896): p. 56-72.
29.
Karaagac, O., B.B. Yildiz, and H. Köçkar, The influence of synthesis parameters on one-step synthesized superparamagnetic cobalt ferrite nanoparticles with high saturation magnetization. Journal of Magnetism and Magnetic Materials, 2019. 473: p. 262-267.
30.
Gupta, V. and A. Mansingh, Influence of postdeposition annealing on the structural and optical properties of sputtered zinc oxide film. Journal of Applied Physics, 1996. 80(2): p. 1063-1073.
31.
Smith, A.M., A.M. Mohs, and S. Nie, Tuning the optical and electronic properties of colloidal nanocrystals by lattice strain. Nature nanotechnology, 2009. 4(1): p. 56.
32.
Chavan, A.R., et al., Cu2+ substituted NiFe2O4 thin films via spray pyrolysis technique and their high-frequency devices application. Journal of Alloys and Compounds, 2018. 769: p. 1132-1145.
33.
Agrawal, S., A. Parveen, and A. Azam, Structural, electrical, and optomagnetic tweaking of Zn doped CoFe2− xZnxO4− δ nanoparticles. Journal of Magnetism and Magnetic Materials, 2016. 414: p. 144-152.
34.
Lin, K.-F., et al., Band gap variation of size-controlled ZnO quantum dots synthesized by sol–gel method. Chemical Physics Letters, 2005. 409(4-6): p. 208-211.
35.
Liu, C., et al., Chemical control of superparamagnetic properties of magnesium and cobalt spinel ferrite nanoparticles through atomic level magnetic couplings. Journal of the American Chemical Society, 2000. 122(26): p. 6263-6267.
36.
Patange, S., et al., Rietveld structure refinement, cation distribution and magnetic properties of Al3+ substituted NiFe2O4 nanoparticles. Journal of Applied Physics, 2011. 109(5): p. 053909.
37.
Sláma, J., et al., Magnetic properties of selected substituted spinel ferrites. Journal of Magnetism and Magnetic Materials, 2013. 326: p. 251-256.
17
Journal Pre-proof 38.
Sharifi, I., H. Shokrollahi, and S. Amiri, Ferrite-based magnetic nanofluids used in hyperthermia applications. Journal of magnetism and magnetic materials, 2012. 324(6): p. 903-915.
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Journal Pre-proof Credit Author Statement 1. Study conception and design: K. M. Jadhav 2. Acquisition of data: Deepali D. Andhare, Supriya R. Patade 3. Analysis and interpretation of data: Deepali D. Andhare, Supriya R. Patade, Jitendra S. Kounsalye, K. M. Jadhav 4. Drafting of manuscript: Deepali D. Andhare, Supriya R. Patade, Jitendra S. Kounsalye, K. M. Jadhav
5. Critical revision: Deepali D. Andhare, K. M. Jadhav
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Affiliation
Deepali D. Andhare, Supriya R. Patade, Jitendra S. Kounsalye, K.M. Jadhav PII:
S0921-4526(20)30065-X
DOI:
https://doi.org/10.1016/j.physb.2020.412051
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PHYSB 412051
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Physica B: Physics of Condensed Matter
Received Date:
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Please cite this article as: Deepali D. Andhare, Supriya R. Patade, Jitendra S. Kounsalye, K.M. Jadhav, Effect of Zn doping on structural, magnetic and optical properties of cobalt ferrite nanoparticles synthesized via. Co-precipitation method, Physica B: Physics of Condensed Matter (2020), https://doi.org/10.1016/j.physb.2020.412051
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Journal Pre-proof Effect of Zn doping on structural, magnetic and optical properties of cobalt ferrite nanoparticles synthesized via. Co-precipitation method Deepali D. Andharea, Supriya R. Patadea, Jitendra S. Kounsalyea,b, K. M. Jadhava* aDepartment
of Physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad – 431004, Maharashtra, India
bDepartment
of Physics, Late Rajkamalji Bharti Arts, Commerce and Smt. S. R. Bharati
Science College, Arni, Yavatmal – 445103, Maharashtra, India *Corresponding
Author: [email protected]
ABSTRACT In the present work, Co1-xZnxFe2O4 (x=0.0, 0.3, 0.5, 0.7 and 1.0) nanoparticles were prepared by chemical co-precipitation method. Prepared Co1-xZnxFe2O4 ferrite powder was sintered at 900ºC for 4h after TG-DTA thermal studies. XRD analysis revealed the single-phase cubic structure of Co-Zn ferrite nanoparticles and also studied the variation in structural parameter with increasing Zn concentration. The formation of the ferrite phase was confirmed by studying FTIR spectra. The SEM images shows the agglomeration of spherical grains due to the difference in the magnetic nature of the sample. Peaks of respective elements (Co, Zn, Fe, and O) in EDX spectra show the formation of cobalt zinc ferrite. Variation of energy band gap with increasing zinc concentration in cobalt ferrite studied by UV-Vis. Spectroscopy. The M-H loops revealed that the values of magnetic parameters such as MS, Mr, Hc, nB, and Mr/Ms ratio decrease with increasing Zn2+ content in cobalt ferrite nanoparticles. Keywords: Cobalt zinc ferrite nanoparticles; Chemical co-precipitation; Optical; Magnetization.
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Journal Pre-proof 1. Introduction In recent years, the use of magnetic nanoparticles has been a vastly increased in biomedical applications. Many researchers have been focused on the improvement of magnetic nanoparticles (MNPs) as well as to improve their applicability in different areas. Investigation of ferrite nanoparticles is very much interested due to their enhanced magnetic and electrical properties [1-3]. Most of the applications such as Magnetic Resonance Imaging (MRI), Magnetic Hyperthermia, drug delivery, biosensors and bioimaging are depends on the magnetic properties such as spin canting effect, superparamagnetism and spin-glass-like behaviour of the magnetic nanoparticles [4-7]. Among the various magnetic nanoparticles spinel ferrite shows excellent optical, electrical, structural and magnetic properties [8]. Spinel ferrite has general formula MFe2O4 (M=Zn, Co, Mn, Ni, Cu, etc.) have many applications in various field, such as biotechnology, catalysis, energy storage device, information storage system, ferrofluid technology, and electronic circuits [9-13]. M. Rahimi et. al. successfully prepared PVA coated Ni0.3Zn0.7Fe2O4 nanoparticles by a solgel auto-combustion method and calculated crystallite size, as well as magnetization, were in the range 17-24nm and 16-19 emu/g respectively [14]. S. Munjal et.al. Synthesized the oleic acid-coated water-dispersible CoFe2O4 nanoparticles by hydrothermal method with improved colloidal stability and also studied its applications in the biomedical field [15]. Rautet. al. synthesized the Zn substituted CoFe2O4 nanoparticles by the sol-gel auto-combustion method and reported the particle size was increased from 45-49nm [16]. Among the various spinel ferrites, cobalt ferrite is an important magnetic metal oxide because of its high coercivity, large magnetostrictive coefficient, and moderate saturation magnetization. The CoFe2O4 has an inverse spinel structure but when divalent metal ions such as Zn, Cd, Ni, etc. are doped in cobalt ferrite, it changes the structure of cobalt ferrite from inverse spinel to normal spinel ferrites[17]. Cobalt ferrite is the hard magnetic material and zinc ferrite is soft but the substitution of Zn2+ ion in cobalt ferrite reduces its hardness. Zinc substituted cobalt ferrites (CoxZn1-xFe2O4) is one of the soft magnetic material having good chemical stability, high coercivity and highly sensitive to temperature [18]. Cobalt ferrite is generally known for its high coercivity and saturation magnetization but the substitution of non-magnetic zinc ion altered its magnetic property from ferromagnetic to superparamagnetic [19]. Magnetic material with superparamagnetic behaviour has huge applications in biomedical science.
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Journal Pre-proof M. Ben Ali et. al. successfully prepared Co-Zn ferrites nanoparticles by the Sol-Gel method and average particle size was increased from 11nm-28nm [20]. M. Madhukara Naik et. al. reported that the Zn1-xCoxFe2O4 nanoparticles prepared by the combustion method and calculated particle size are in the range 21nm-12nm [21]. Magnetic nanoparticles are synthesized by various synthesis techniques such as sol-gel auto-combustion, microemulsion, hydrothermal technique, and forced hydrolysis method [22]. But the coprecipitation method is broadly used for the synthesis of spinel ferrite nanoparticles due to its number of good points like it is a time-consuming method, cost-effective, simple to do and reliable, etc. [23]. The chemical co-precipitation method produces a homogeneous powder with maximum yield and does not require any organic fuels like citric acid etc. Thus, in the present study, we have synthesized Co1-xZnxFe2O4 with x value 0, 0.3, 0.5, 0.7, and 1 nanoparticles by co-precipitation method. Aim of the present work is to study the effect of Zn substitution on thermal, structural, magnetic, optical, morphological and elemental properties of Co-Zn ferrite nanoparticles investigated by TG-DTA, XRD, VSM, UV-Vis. Spectroscopy, SEM, and EDX respectively. 2. Experimental 2.1. Materials and methods Co1-xZnxFe2O4 ferrite nanoparticles with x=0.0, 0.3, 0.5, 0.7 and 1 were synthesized by the co-precipitation method. Analytical grade cobalt chloride hexahydrate (CoCl2.6H2O), zinc chloride (ZnCl2), ferric chloride (FeCl3) and sodium hydroxide (NaOH) were used as raw materials. Nanoparticles prepared by co-precipitating aqueous solutions of CoCl2.6H2O, ZnCl2, and FeCl3. Initially, the solutions of CoCl2.6H2O, ZnCl2, and FeCl3 were mixed in their respective stoichiometric amounts (7 ml of 1M CoCl2.6H2O, 3 ml of 1M ZnCl2 and 10 ml of 1M FeCl3 in case of Co0.7Zn0.3Fe2O4 and similarly for the other values of x) at room temperature with constant stirring for 30 min. 1M NaOH was added drop-wise into the solution, to adjust pH at 11. The solution was heated at 80°C under constant stirring. After 2 hours constant stirring and heating ageing process were completed. The solution was cooled down to room temperature under stirring that the nanoparticles set to the bottom of the beaker. The solution was washed to separate out substance from precipitated solution with acetone or hot DI-water to extract traces of water and sodium chloride respectively. Then, the precipitate was settled down by using centrifugal separator after washing with acetone. The nanoparticles were dried at room temperature for 48 h. The as-prepared Co1-xZnxFe2O4 spinel 3
Journal Pre-proof ferrite powder was ground for 40 minutes and the thermal stability of the prepared sample was measured by TG-DTA up to 1200 ºC. Hence, samples sintered at 900 oC for 4 h in the furnace. Prepared powder samples were characterized by different characterization techniques. 2.2. Characterizations To study the change in mass of the sample and decomposition mechanism of Co1-xZnxFe2O4 ferrite sample as the function of temperature was investigated by TG-DTA (Shimazdu DTA60H) technique. Thermal analysis (TG-DTA) was carried out under a nitrogen atmosphere and temperature varying from 23ºC to 1200ºC. The structural properties of prepared samples of Co1-xZnxFe2O4 (x=0, 0.3, 0.5, 0.7, and 1) ferrites were studied by recording the X-ray diffraction (XRD) diffraction pattern at room temperature. The powder form of samples was characterized by using X-ray diffractometer (Bruker) with Cu Kα (λ=1.5406Å) radiation, operated at 20 mA current and 40 kV voltage. The XRD pattern was recorded in the 2θ range of 20° ˃ 2θ ˃ 80°. The analysis of the functional group was carried out from FTIR spectra. FT-IR spectra of prepared nanoparticles were recorded on Shimazdu FTIR spectrometer at room temperature within the wavenumber range 400cm-1 to 2000 cm-1. The light absorption spectrum in the UV-Visible range 200nm to 800nm was recorded using UV-Vis. Spectroscopy to estimate the variation of optical bandgap with increasing Zn content. By using UV-Visible analysis, the optical bandgap (Eg) was calculated by the following equation; ∝ 𝐸𝑝 = 𝐴(𝐸𝑝 ― 𝐸𝑔)𝑞 Where, is the absorption coefficient, Ep is the photon energy, A is a constant and q depends on transition nature. The surface structure of all prepared samples was examined by SEM through JEOL (JSM-5600) and the elemental concentration distribution was carried out by EDX. Magnetic measurements of all prepared samples were recorded by using VSM (Quantum Design–Modular control system) at below room temperature that is at 5K with an applied ± 30 kOe magnetic field.
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Journal Pre-proof 3. Results and discussion 3.1. Thermo - Gravimetric and Differential Thermal Analysis (TG-DTA) TG-DTA was performed under a nitrogen atmosphere in such a way that temperature varies from 23ºC to 1200ºC with heating rate 20ºC/min. According to TG–DT analysis it is clear that the removal of water, decomposition of metal hydroxide and formation of spinel ferrite can be completed below 900ºC temperature[24]. Three different weight losses exhibit in the TGA curve and DTA curve shows two endothermic and one exothermic peak corresponding to each weight loss[25]. First weight loss (10%) and first endothermic peak (at 90ºC) arises due to the ejection of moisture which is in the 30ºC-400ºC temperature range. Second weight loss (4%) and exothermic peak (at 427ºC) is in 400ºC-827ºC temperature range shows the decomposition of metal hydroxide. Third weight loss (3%) and second endothermic peak (at 875ºC) is in the temperature range 827ºC-900ºC indicates the formation of spinel ferrite. Total weight loss in all three samples is about 17%. Therefore, prepared nanoparticles were sintered at 900 ºC for 4h.
Fig.1 TG-DTA curve of Co1-xZnxFe2O4 ferrite nanoparticles.
3.2. X-ray Diffraction (XRD) Figure 2 shows XRD patterns of Co1-xZnxFe2O4 (x=0, 0.3, 0.5, 0.7, and 1) nanoparticles. XRD patterns of all samples reveal that the presence of reflection planes having (h k l) values as (220), (311), (222), (400), (422), (511), (440), (620), and (533) indicates the cubic spinel structure for all the sample with exhibition of Fd-3m space group, which is confirmed by JCPDS card no. 221086 (for cobalt ferrite, when x=0) and 891012 (for zinc ferrite, when x=1). It is evident from JCPDS values that angles corresponding to zinc ferrite (values of 2θ = 35.27, 62.225, 56.671) are lower than cobalt ferrite (values of 2θ = 35.437, 30.084, 62.585, 56.973). From figure 2 it is clear that the corresponding peak positions are shifted towards 5
Journal Pre-proof lower angle with the substitution of Zn content in the cobalt ferrite matrix. No any additional peak related to impurity observed in pattern indicates that high purity of the prepared samples. The position (2θ) of the XRD peaks and their FWHM are used to estimate the lattice parameter with the following equation [26], sin2 𝜃 = (𝜆2 𝑎2)(ℎ2 + 𝑘2 + 𝑙2) Where a is the lattice parameter, θ is the diffraction angle, λ is the wavelength of the X-ray and h, k, l are miller indices of each plane family. The lattice parameter was found in the range 8.3737 Å -8.4303 Å. The value of the lattice parameter increases with increasing zinc concentration this is probably due to the difference in ionic radius of Co2+ (0.72 Å) and Zn2+ (0.74 Å). The crystallite size of all prepared samples was calculated by using DebyeScherrerʼs equation[27] 𝑡=
𝑘𝜆 (𝛽𝑐𝑜𝑠𝜃)
Where t is the crystallite size of the particles, λ is the X-ray wavelength, k is a constant (value of k is 0.9), θ is the angle of diffraction and β is the full width at half maximum (FWHM). Particles size of the prepared samples was obtained between 12 nm to 17 nm which increases with the concentration of zinc. The X-ray density was calculated by using the formula[28] 𝑑𝑥 = 8𝑀 (𝑁𝐴𝑎3) Where dx is X-ray density, M molecular weight of the composition, NA is the Avogadro′s number and ʽaʼis the lattice parameter. X-ray density was varying from 5.3079 g/cm3 to 5.3447 g/cm3 with a concentration of zinc. Using Archimedes principle bulk density (dB) of all samples was measured which is observed to decreases from 3.638 g/cm3to 3.488 g/cm3 with an increasing concentration of zinc in Co-Zn ferrite nanoparticles. Porosity (P%) of the sample was calculated using the values of dx and dB, which is increased from 31.46% to 34.73% as the value of zinc concentration (i.e. x=0, 0.3, 0.5, 0.7, and 1) increases in Co-Zn ferrite nanoparticles. The variation in crystallite size, the lattice constant, X-ray density, Bulk density and porosity with respect to increasing zinc concentration in cobalt ferrite is shown in table 1.
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Fig.2. XRD pattern of Co1-xZnxFe2O4( x=0, 0.3, 0.5, 0.7 and 1)
Table 1 Variation of lattice constant ʽaʼ (Å), Crystallite size ʽtʼ (nm), X-ray density ʽdxʼ (g/cm3), Bulk density ʽdBʼ(g/cm3), Porosity (%), lattice volume (Å3) of Co1-xZnxFe2O4 (x=0, 0.3, 0.5, 0.7, 1) spinel ferrite nanoparticles. Composition
a (Å)
t (nm)
dX(g/cm3)
dB(g/cm3)
P (%)
V (Å3)
CoFe2O4
8.3737
12
5.3079
3.638
31.46
589.2
Co0.7Zn0.3Fe2O4
8.3940
13
5.3129
3.617
31.91
591.4
Co0.5Zn0.5Fe2O4
8.4080
15
5.3153
3.587
32.52
594.4
Co0.3Zn0.7Fe2O4
8.4200
16
5.3213
3.537
33.53
596.9
ZnFe2O4
8.4303
17
5.3447
3.488
34.73
599.1
3.3. Fourier - Transform Infrared Spectroscopy (FT-IR) The FT-IR spectra of prepared Co-Zn nanoparticles were carried out in the range of 400 2000 cm-1 at room temperature for the identification of chemical bonds present in the sample and ensures the formation of the ferrite phase. Two main absorption peaks in FTIR spectra indicate the intrinsic stretching-vibrations of oxygen with metal which is the characteristic of spinel ferrite[29]. FT-IR spectra of Co1-xZnxFe2O4 (x=0, 0.3, 0.5, 0.7, 1) ferrite samples show in figure 3. The first band (ʋ1) observed with the higher wavenumber in the range 533-550 cm-1 corresponds to the stretching vibrations of the M-O at the tetrahedral site. The other band (ʋ2) with the lower wavenumber appeared around 392-396 7
Journal Pre-proof cm-1 is attributed to the octahedral metal-oxygen stretching[20]. The band positions of all samples are shown in table 2. The frequency band shifted with the variation in zinc concentration, this may be due to Co, Zn and Fe cations redistribution on both sites. Ferrite phase formation of all samples was confirmed by analyzing attribute peaks in FTIR spectra.
Fig.3. FTIR Spectra for Co1-xZnxFe2O4 (x=0, 0.3, 0.5, 0.7 and 1).
Table 2. Comparison of the main FTIR transmittance bands for Co1-xZnxFe2O4 with x = 0, 0.3, 0.5, 0.7 and 1.s Composition
ʋ1 (cm-1)
ʋ2 (cm-1)
CoFe2O4
533.76
396.43
Co0.7Zn0.3Fe2O4
536.92
396.56
Co0.5Zn0.5Fe2O4
545.70
398.79
Co0.3Zn0.7Fe2O4
548.84
398.02
ZnFe2O4
550.68
399.86
3.4. UV-Vis. Spectroscopy Study The optical properties of the samples Co1-xZnxFe2O4 (x= 0, 0.3, 0.5, 0.7, and 1) nanoparticles were investigated by UV-Vis spectroscopy. A spectrometer in the photon wavelength range 200-800nm shown in figure 4. The absorbance normally depends on a number of factors such as impurity centers, grain size, bandgap, lattice parameter, and surface roughness[30]. The absorption spectra are shown in figure 4a. From figure 4a clearly show that there is no visible 8
Journal Pre-proof absorption observed. The absorption spectra indicate the higher absorption peak shifted towards higher wavelength with increasing zinc concentration, this shift indicates that the change in optical bandgap due to the effect of quantum confinement. The absorption coefficient of nanoparticles was calculated by the equation[31] ∝=
2.303 × 𝐴 𝑡
Where, is the absorption coefficient, A is absorbance and t is the thickness of the sample. The optical bandgap of samples was calculated by using the Tauc plot. The energy band gap of Co-Zn spinel ferrite nanoparticles was calculated by using allowed direct bandgap expression given below[32]; 1
𝛼ℎ𝜗 = 𝐴(ℎ𝜗 ― 𝐸𝑔)
2
Were, Eg is bandgap A is constant, is absorption coefficient, hυ is photon energy. The hυ versus (αhυ) 2 plot for all samples shown in figure 4b optical band gap values are calculated from intercept made by the extrapolating liner part of the curve. The energy band gap decreases from 2.8306 eV to 2.258 eV with increasing Zn concentration in Cobalt ferrite shown in table 3. The decrease in bandgap with an increase in particle size can be attributed to Brassʼs model. According to this model energy bandgap associated with particle size by the relation; ℏ2𝜋2 1 𝑚𝑒
+ 2𝑒𝑟2 𝐸𝑔 = 𝐸𝑏𝑢𝑙𝑘 𝑔
(
1
)
1.8𝑒2
+ 𝑚ℎ ― 4𝜋𝜀𝜀 ⃘𝑟
Where Eg is the bandgap, Egbulk is the bulk energy gap, ℏ is equal to h/2𝝅, r is the particle size, me is the effective mass of electrons, mh is the effective mass of holes, ε is the relative permittivity, ε0 is the permittivity of free space, and e is charge of electrons. A similar explanation was also repeated in the literature [33, 34]. Hence energy band gap affected by increasing crystallite size and lattice constant.
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Fig.4. UV-Vis. Spectra of Co1-xZnxFe2O4 (x= 0, 0.3, 0.5, 0.7, and 1) nanoparticles
Table 3 Bandgap energy of Co1-xZnxFe2O4 (x= 0, 0.3, 0.5, 0.7, and 1) nanoparticles Composition
CoFe2O4
Co0.7Zn0.3Fe2O4
Co0.5Zn0.5Fe2O4
Co0.3Zn0.7Fe2O4
ZnFe2O4
Band gap (eV)
2.830
2.566
2.447
2.326
2.258
3.5. SEM/EDX analysis The morphology of prepared Co1-xZnxFe2O4 (x=0, 0.3, 0.5, 0.7, 1) nanoparticles was observed by scanning electron microscopy (SEM). The SEM images of particles shown in figure 5 at 1μm scale. SEM images substantiate the formation of nanocrystalline grain having spherical nature and showed higher agglomeration. The agglomeration occurred due to magnetic dipole-dipole interaction, this interaction decreases with increasing zinc concentration in the cobalt ferrite nanoparticles[19]. The magnetization of cobalt ferrite is higher than zinc ferrite hence, doping of zinc in cobalt ferrite causes a decrease in magnetization it resulted that the attractive force in nanoparticles goes on decreasing. So the agglomeration depends on the concentration of zinc in cobalt ferrite nanoparticles shown in the SEM image. The elemental composition of samples Co1-xZnxFe2O4 (x=0, 0.3, 0.5, 0.7, 1) was carried out by Energy-dispersive X-ray spectroscopy(EDX). Figure 5 shows EDX spectra for all zinc substituted cobalt ferrite nanoparticles, which clearly indicates the presence of Co, Zn, O and Fe elemental peaks. No, any other elemental peak was observed in the EDX spectrum which indicated the purity of the sample. Elemental compositions of all elements present in the 10
Journal Pre-proof prepared samples are shown in Table 4 this result indicates that the obtained atomic ratio of all elements (Co, Zn, O, and Fe) was well-matched with the expected stoichiometric proportion of elements in synthesized nanoparticles.
Fig.5. SEM with EDX image of the Co1-xZnxFe2O4 sample (a)x=0, (b)x=0.3, (c)x=0.5, (d)x=0.7 and (e)x=1
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Journal Pre-proof Table 4 The elemental composition of synthesized Co1-xZnxFe2O4 (x=0.0, 0.3, 0.5, 0.7, and 1) Composition
at%
CoFe2O4
Co 15.94
Zn -
Fe 27.70
O 57.36
Co0.7Zn0.3Fe2O4
10.80
4.51
28.72
56.97
Co0.5Zn0.5Fe2O4
7.65
7.07
28.14
57.61
Co0.3Zn0.7Fe2O4
4.91
10.06
28.08
57.65
-
14.28
28.58
57.90
ZnFe2O4
3.6. Magnetic properties Magnetic properties of synthesized Co1-xZnxFe2O4 (x=0, 0.3, 0.5, 0.7 and 1) nanoparticles were characterized by VSM at 5K temperature with an applied magnetic field 30000 Oe. Figure 6 shows the M-H loop of prepared samples. The values of various magnetic parameters of samples such as MS, Mr, Hc, Mr/Ms ratio, and nB measured from the M-H plots are listed in Table 5. Magnetic properties of spinel ferrite depend on the particle size, cation distribution, and doping. In the case of spinel ferrite cobalt ferrite shows hard magnetic behaviour as compared to Zinc ferrite[35]. Zn2+ ions have zero magnetic moments. The substitution of Zn2+ ions at tetrahedral (A) site replaces magnetic Fe3+ ions which causes decrease magnetic moment at A-site. The higher concentration of Fe3+ and Co2+ magnetic ions at B-site leads to enhance B-B exchange interaction and weakening of A-B interaction[36]. The weakening of A-B magnetic interaction decreases due to diamagnetic zinc substitution. As a result of zinc substitution, magnetic properties of cobalt ferrite decreased[37]. The different magnetic parameters were calculated from M-H plots, the saturation magnetization decreases from 60 emu/g to 43 emu/g, remanence magnetization decreases from 43 emu/g to 29 emu/g and coercivity decreases from 3309 Oe to 1630 Oe with increasing Zn concentration this variation was explained graphically in figure 6. From the M-H plot, it is clear that all samples reveal ferromagnetic nature but magnetization decreases with increasing Zn2+ ions. The variation in magneton number ‘nB’ is related to A-B interaction and it was calculated using the relation, 𝑛𝐵 =
[𝑀𝑠 × 𝑀𝑤 ]
12
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Fig.6. Magnetization hysteresis loop of Co1-xZnxFe2O4nanoparticlesand variation of Ms(emu/g) and Hc(Oe) with Zn concentration calculated at low temperature (5K) temperature.
Were, MS is saturation magnetization; MW is the molecular weight of the composition. Magneton numbers (nB) sharply decreases from 2.5469 μB to 1.8883 μB when the value of x is varied from 0.0 to 1.0. The Squareness ratio that is the ratio of remanence magnetization with saturation magnetization (Mr/Ms) of all prepared samples was observed decreasing from 0.7177 to 0.6668 with increasing concentration of zinc from 0.0 to 1.0 in cobalt ferrite. This study confirms the magnetization or magnetic properties decreases with increasing Zn concentration maybe because of the non-magnetic nature of zinc, due to particle size effect or due to exchanging A-B interaction[38]. Table 5 The values of magnetic parameters calculated from M-H loops observed at 5K of Co1xZnxFe2O4
nanoparticles.
Composition
Ms (emu/g)
Mr (emu/g)
Hc (Oe)
Mr/Ms
nB (μB)
CoFe2O4
60.63
43.52
3309
0.7177
2.5469
Co0.7Zn0.3Fe2O4
56.66
41.03
2680
0.7241
2.3997
Co0.5Zn0.5Fe2O4
50.14
33.39
2226
0.6659
2.1351
Co0.3Zn0.7Fe2O4
48.84
32.11
1639
0.6575
2.0911
ZnFe2O4
43.75
29.24
1630
0.6683
1.8883
13
Journal Pre-proof 4. Conclusion Co1-xZnxFe2O4 ferrite nanoparticles with x value 0.0, 0.3, 0.5, 0.7 and 1were successfully synthesized by co-precipitation method. Co1-xZnxFe2O4 (x=0, 0.3, 0.5, 0.7, and 1) nanoparticles possess single-phase cubic spinel structure was confirmed by XRD analysis. The crystallite size increases with increase Zn substitution in prepared samples were observed from the XRD study. Structural parameters such as lattice constant and X-ray density increase with increasing zinc concentration. Two main absorption peaks near 400 cm-1 and 600 cm-1 observed in FTIR spectra which confirmed the ferrite nature of the sample. SEM image shows the spherical nature of grains and the agglomeration decreases with increasing zinc concentration. The stoichiometric proportion of elements present in prepared samples was confirmed by EDX spectra. The energy band gap of prepared samples calculated from the Tauc plot increases from 2.258 eV to 2.8306 eV with increasing Zn concentration. Hysteresis loop of ZnFe2O4 is very small as compared to CoFe2O4 which concluded that the zinc ferrite is soft magnetic material than cobalt ferrite. From the present study, it can be concluded that with increasing substitution of Zn2+ in cobalt ferrite magnetic properties go on decreases. Acknowledgements The Author (Miss. Deepali D. Andhare) is thankful to Dr. V. Ganesan, Ex-centre director of UGC-DAE consortium for scientific research, Indore, India for providing UV-Vis spectroscopy measurement facilities. Authors are grateful to Dr. Alok Banerjee center director of UGC-DAE consortium for scientific research, Indore, India for providing vibrating sample magnetometer (VSM) measurement facilities and also thankful to Dr. D. M. Phase and Dr. V. K. Ahire scientist UGC-DAE consortium for scientific research, Indore, India for providing SEM and EDAX measurement facility. Conflict of Interest No conflict of interest. References 1.
Gordani, G.R., A. Ghasemi, and A. Saidi, Enhanced magnetic properties of substituted Sr-hexaferrite nanoparticles synthesized by co-precipitation method. Ceramics International, 2014. 40(3): p. 4945-4952.
14
Journal Pre-proof 2.
Kahn, M.L. and Z.J. Zhang, Synthesis and magnetic properties of CoFe 2 O 4 spinel ferrite nanoparticles doped with lanthanide ions. Applied Physics Letters, 2001. 78(23): p. 3651-3653.
3.
Bharati, V., et al., Influence of trivalent Al–Cr co-substitution on the structural, morphological and Mössbauer properties of nickel ferrite nanoparticles. Journal of Alloys and Compounds, 2019: p. 153501.
4.
Somvanshi, S.B., et al. Investigations of structural, magnetic and induction heating properties of surface functionalized zinc ferrite nanoparticles for hyperthermia applications. in AIP Conference Proceedings. 2019. AIP Publishing.
5.
Somvanshi, S.B., et al., Hydrophobic to hydrophilic surface transformation of nanoscale zinc ferrite via oleic acid coating: magnetic hyperthermia study towards biomedical applications. Ceramics International, 2019.
6.
Patade, S.R., et al., Preparation and Characterizations of Magnetic Nanofluid of Zinc Ferrite for Hyperthermia Application. Nanomaterials and Energy, 2020: p. 1-7.
7.
Kale, S.B., et al. Enhancement in surface area and magnetization of CoFe2O4 nanoparticles for targeted drug delivery application. in AIP Conference Proceedings. 2018. AIP Publishing LLC.
8.
Somvanshi, S.B., et al., Influential diamagnetic magnesium (Mg2+) ion substitution in nano-spinel zinc ferrite (ZnFe2O4): Thermal, structural, spectral, optical and physisorption analysis. Ceramics International, 2019.
9.
Alone, S., et al., Chemical synthesis, structural and magnetic properties of nanostructured Co–Zn–Fe–Cr ferrite. Journal of Alloys and Compounds, 2011. 509(16): p. 5055-5060.
10.
Kharat, P.B., et al. Temperature dependent viscosity of cobalt ferrite/ethylene glycol ferrofluids. in AIP Conference Proceedings. 2018. AIP Publishing LLC.
11.
Kharat, P.B., et al., Exploration of thermoacoustics behavior of water based nickel ferrite nanofluids by ultrasonic velocity method. Journal of Materials Science: Materials in Electronics, 2019. 30(7): p. 6564-6574.
12.
Borade, R.M., et al., Spinel zinc ferrite nanoparticles: an active nanocatalyst for microwave irradiated solvent free synthesis of chalcones. Materials Research Express, 2020.
13.
Babrekar, M. and K. Jadhav, Synthesis and characterization of spray deposited lithium ferrite thin film. Int. Res. J. Sci. Eng. Special, 2017(A1): p. 73-76.
15
Journal Pre-proof 14.
Rahimi, M., et al., The effect of polyvinyl alcohol (PVA) coating on structural, magnetic properties and spin dynamics of Ni0. 3Zn0. 7Fe2O4 ferrite nanoparticles. Journal of Magnetism and Magnetic Materials, 2013. 347: p. 139-145.
15.
Munjal, S., et al., Water dispersible CoFe2O4 nanoparticles with improved colloidal stability for biomedical applications. Journal of Magnetism and Magnetic Materials, 2016. 404: p. 166-169.
16.
Raut, A., et al., Synthesis, structural investigation and magnetic properties of Zn2+ substituted cobalt ferrite nanoparticles prepared by the sol–gel auto-combustion technique. Journal of Magnetism and Magnetic Materials, 2014. 358: p. 87-92.
17.
Coppola, P., et al., Hydrothermal synthesis of mixed zinc–cobalt ferrite nanoparticles: structural and magnetic properties. Journal of Nanoparticle Research, 2016. 18(5): p. 138.
18.
Hossain, M., Study of the Magnetic and Transport Properties of Ytterbium Doped CoZn Ferrites. 2018, Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh.
19.
Topkaya, R., A. Baykal, and A. Demir, Yafet–Kittel-type magnetic order in Znsubstituted cobalt ferrite nanoparticles with uniaxial anisotropy. Journal of nanoparticle research, 2013. 15(1): p. 1359.
20.
Ali, M.B., et al., Effect of zinc concentration on the structural and magnetic properties of mixed Co–Zn ferrites nanoparticles synthesized by sol/gel method. Journal of Magnetism and Magnetic Materials, 2016. 398: p. 20-25.
21.
Naik, M.M., et al., Green synthesis of zinc doped cobalt ferrite nanoparticles: Structural, optical, photocatalytic and antibacterial studies. Nano-Structures & NanoObjects, 2019. 19: p. 100322.
22.
Yadav, R.S., et al., Magnetic properties of Co1− xZnxFe2O4 spinel ferrite nanoparticles synthesized by starch-assisted sol–gel autocombustion method and its ball milling. Journal of Magnetism and Magnetic Materials, 2015. 378: p. 190-199.
23.
Amri, A., et al., Developments in the synthesis of flat plate solar selective absorber materials via sol–gel methods: a review. Renewable and Sustainable Energy Reviews, 2014. 36: p. 316-328.
24.
Bardhan, A., et al., Low temperature synthesis of zinc ferrite nanoparticles. Solid State Sciences, 2010. 12(5): p. 839-844.
25.
Tianshu, Z., et al., Ethanol-sensing characteristics of cadmium ferrite prepared by chemical coprecipitation. Materials Chemistry and Physics, 1999. 61(3): p. 192-198. 16
Journal Pre-proof 26.
O’Donnell, M., et al., Structural analysis of a series of strontium-substituted apatites. Acta Biomaterialia, 2008. 4(5): p. 1455-1464.
27.
Yan, H., et al., Influences of different synthesis conditions on properties of Fe3O4 nanoparticles. Materials Chemistry and Physics, 2009. 113(1): p. 46-52.
28.
Bradley, A.J. and u.A. Taylor, An X-ray analysis of the nickel-aluminium system. Proceedings of the Royal Society of London. Series A-Mathematical and Physical Sciences, 1937. 159(896): p. 56-72.
29.
Karaagac, O., B.B. Yildiz, and H. Köçkar, The influence of synthesis parameters on one-step synthesized superparamagnetic cobalt ferrite nanoparticles with high saturation magnetization. Journal of Magnetism and Magnetic Materials, 2019. 473: p. 262-267.
30.
Gupta, V. and A. Mansingh, Influence of postdeposition annealing on the structural and optical properties of sputtered zinc oxide film. Journal of Applied Physics, 1996. 80(2): p. 1063-1073.
31.
Smith, A.M., A.M. Mohs, and S. Nie, Tuning the optical and electronic properties of colloidal nanocrystals by lattice strain. Nature nanotechnology, 2009. 4(1): p. 56.
32.
Chavan, A.R., et al., Cu2+ substituted NiFe2O4 thin films via spray pyrolysis technique and their high-frequency devices application. Journal of Alloys and Compounds, 2018. 769: p. 1132-1145.
33.
Agrawal, S., A. Parveen, and A. Azam, Structural, electrical, and optomagnetic tweaking of Zn doped CoFe2− xZnxO4− δ nanoparticles. Journal of Magnetism and Magnetic Materials, 2016. 414: p. 144-152.
34.
Lin, K.-F., et al., Band gap variation of size-controlled ZnO quantum dots synthesized by sol–gel method. Chemical Physics Letters, 2005. 409(4-6): p. 208-211.
35.
Liu, C., et al., Chemical control of superparamagnetic properties of magnesium and cobalt spinel ferrite nanoparticles through atomic level magnetic couplings. Journal of the American Chemical Society, 2000. 122(26): p. 6263-6267.
36.
Patange, S., et al., Rietveld structure refinement, cation distribution and magnetic properties of Al3+ substituted NiFe2O4 nanoparticles. Journal of Applied Physics, 2011. 109(5): p. 053909.
37.
Sláma, J., et al., Magnetic properties of selected substituted spinel ferrites. Journal of Magnetism and Magnetic Materials, 2013. 326: p. 251-256.
17
Journal Pre-proof 38.
Sharifi, I., H. Shokrollahi, and S. Amiri, Ferrite-based magnetic nanofluids used in hyperthermia applications. Journal of magnetism and magnetic materials, 2012. 324(6): p. 903-915.
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Journal Pre-proof Credit Author Statement 1. Study conception and design: K. M. Jadhav 2. Acquisition of data: Deepali D. Andhare, Supriya R. Patade 3. Analysis and interpretation of data: Deepali D. Andhare, Supriya R. Patade, Jitendra S. Kounsalye, K. M. Jadhav 4. Drafting of manuscript: Deepali D. Andhare, Supriya R. Patade, Jitendra S. Kounsalye, K. M. Jadhav
5. Critical revision: Deepali D. Andhare, K. M. Jadhav
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