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Synthesis and magnetic properties of octahedral Fe3O4 via a one-pot hydrothermal route
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Discussion
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Synthesis and magnetic properties of octahedral Fe3 O4 via a one-pot hydrothermal route
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Wei Lei, Yongsheng Liu ∗ , Xiaodong Si, Juan Xu, Wenlong Du, Jie Yang, Tao Zhou, Jia Lin
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Article history: Received 6 May 2016 Received in revised form 12 September 2016 Accepted 16 September 2016 Available online xxxx Communicated by R. Wu Keywords: Fe3 O4 Hydrothermal synthesis Octahedra Magnetic properties
Magnetite (Fe3 O4 ) particles were prepared by a facile one-step hydrothermal method in assistant of α -Propylene glycol solution (PG). The X-ray diffraction (XRD), FT–IR analysis and the Verwey transition confirmed that as-prepared magnetite particles were pure spinel Fe3 O4 without any impurity. Scanning electron microscopy (SEM) showed that the particles have octahedral morphology and the average edge length of these octahedra was about 500 nm. The shape of crystals can be controlled by the growth rates along different directions, and the growth mode of the Fe3 O4 octahedron was outlined. The magnetic measurement at room temperature suggested that the saturation magnetization (M s ) and coercivity (H c ) were 87.48 emu/g and 95.6 Oe, respectively. Fe3 O4 nanoparticles showed a sharp transition (Verwey transition) at around 120 K, where the magnetic easy axis switches from the <111> to <100> direction. The value of H c decreased with the increase of the test temperature, resulting from a fact that the effective magnetic anisotropy decreased with the increase of the test temperature. © 2016 Published by Elsevier B.V.
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1. Introduction
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Different forms of iron oxide such as magnetite (Fe3 O4 ), maghemite (γ -Fe2 O3 ) and hematite (α -Fe3 O4 ) are technologically very important [1–3]. Magnetic materials have been extensively studied in the last 50 years, among them, Fe3 O4 is one of the representative magnetic materials and has elicited increasing interests due to its environmental friendly, interesting magnetic behaviors, and potential applications in areas such as magnetic storage devices, electro-photo graphic developer, pigment, protein separation, drug delivery, dynamic sealing, and magnetic resonance images (MRI) [4–9]. Fe3 O4 possesses an inverse spinel structure with a +3 chemical formula FeA [Fe+2 Fe+3 ]B O4 [10,11], in which A sites (tetrahedral sites) are occupied by Fe3+ and B sites (octahedral sites) are occupied by equal numbers of Fe2+ and Fe3+ . At temperature below the Curie point (∼860 K), Fe3 O4 is ferromagnetic with the A-site moments aligned antiparallel to the B-sites and has spontaneous magnetization [12,13]. The nature of ferromagnetic materials is determined by many factors, such as saturation magnetization is an intrinsic property of ferromagnetic, it is not only independent of temperature but also dependent of particle size and morphology [14]. While, the size and morphology of the particle are mainly determined by the preparation process.
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Corresponding author. Fax: +86 21 68025889. E-mail address: [email protected] (Y. Liu).
http://dx.doi.org/10.1016/j.physleta.2016.09.018 0375-9601/© 2016 Published by Elsevier B.V.
During the last few years, various synthetic approaches have been used for the preparation of magnetic Fe3 O4 , such as hydrothermal process [15], co-precipitation method [16], sol–gel route [17], microwave synthesis [18], microemulsion method [19], and ultrasound irradiation [20]. The resulting Fe3 O4 showed various morphologies, for example, particles [21], belts [22], rings [23], and hollow spheres [24]. Among these methods, the hydrothermal method is particularly attractive because of several advantages: (1) resulting materials in a good crystallinity and particle size; (2) economic and environmental friendly; (3) controllable morphologies [25,26]. In our previous papers [27–29], nano-structure, DMSs, magnetic properties, and magnetocaloric effect have been investigated in Mn–Zn nano-ferrite, Co bulk metallic glass and Mg– Al co-doped ZnO, and some results have been obtained. In this work, we synthesized octahedral Fe3 O4 by a facile one-step hydrothermal method in assistant with PG. The structural and magnetic properties of the resulting Fe3 O4 have been investigated in detail.
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2. Experimental section
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2.1. Material preparation
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All reagents were analytical grade and used as received without further purification. In a typical synthetic procedure, 0.328 g of FeSO4 ·7H2 O was dissolved in 10 mL of deionized water, subsequently, it was slowly dropped into the 22 mL of PG by drop.
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Fig. 1. XRD pattern of the synthesized Fe3 O4 : (a) PG; (b) Without PG.
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In addition, the mixed solution was stirring for 1 h. Then 1.6 g of NaOH was added. The mixture was stirred for another 10 min allowing the formation of a homogeneous solution, subsequently it was transferred into a 50 mL Teflon-lined stainless steel autoclave, sealed, then heat up to 200 ◦ C at a speed of 10 ◦ C/min and maintained at 200 ◦ C for 20 h. After the reaction, the autoclave was naturally cooled to room temperature. A black solid was collected by centrifugation and washed three times with deionized water and anhydrous ethanol, respectively. Then, the products were dried under vacuum at 60 ◦ C for 12 h.
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2.2. Characterization
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The resulting samples was characterized by a X-ray power diffraction (XRD, Bruker-Axs, D8 Advance) with Cu Kα radiation (λ = 1.5406 Å). Morphology of the samples was examined by a scanning electron microscopy (SEM, XL30 S-FEG). The optical property was characterized by an infrared spectrometer (SHIMADZU FTIR-8400S). Magnetic measurement was performed by a physical properties measurement system (PPMS/Quantum Design).
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3. Results and discussion
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Fig. 1 shows the XRD pattern of the products. All the diffraction peaks of the sample can be indexed to a cubic phase (fcc, space group Fd-3 m) of magnetite structure according to JCPDS card No. 89-0688 and No. 76-1849. The lattice constants were a(PG) = 8.405 Å, a(without PG) = 8.400 Å. It is agreement with the literature [30,31], which the value is 8.337∼8.419 Å. No peaks assigned to hematite, metal hydroxides, or other impurities were detected, indicating high purity and crystallinity of the sample. Therefore, we can know that whether PG was added into the reaction system or not, the products were pure face-centered cubic phase of Fe3 O4 . According to Debye–Scherrer formula [32], take the half peak width of 2 theta = 35.4 degrees, the average gain size of Fe3 O4 particles are 71.67 and 91.59 nm. It is worth noting that the intensity ratios of the (111)/(400) peaks for the Fig. 1(a) and (b) are 0.3 and 0.48, respectively. Indicating that the growth rate of <111> direction becomes slower, after the PG was added. The products were examined by FT–IR to ascertain its chemical composition. The FT–IR spectrum was shown in Fig. 2. A band at about 583 and 456 cm−1 attributed to the intrinsic stretching vibrations of the metal at tetrahedral site (Fetetra ↔ O) and octahedral site (Feocta ↔ O) [33], indicating that pure-phase Fe3 O4 was synthesized successfully whether PG was added into the reaction
Fig. 2. FT–IR spectra of the synthesized Fe3 O4 : (a) PG; (b) Without PG.
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system or not. Meanwhile, a broad characteristic band at around 3460 cm−1 is attributed to the stretching modes of H2 O molecules or –OH groups on the surface of magnetite particles. A band at around 1635 cm−1 can be assigned to the bending vibrations of H2 O [34,35]. In the curve of Fig. 2(a), the peaks at around 2851 and 1428 cm−1 are corresponded to the bond stretching vibration and bending vibration of C–H in –CH2 , respectively. The absorption peak near 1100 cm−1 is corresponded to the bond stretching vibration of C–O, which is consistent with C–O–C and C–O–H in PG [36]. The offset of the Fe–O peaks shows that there are some interactions between PG molecules and Fe3 O4 crystal. The morphology of the products were characterized by SEM. Fig. 3a and 3b display the SEM images of the Fe3 O4 particles synthesized in the PG and without PG. As observed in two images, the Fe3 O4 particles synthesized in the PG is relatively uniform octahedral morphology. While, in the absence of PG, the Fe3 O4 particles synthesized is disorder. The average edge length of these octahedra was measured to be about 500 nm. The difference between the particle size obtained by SEM and the crystallite size calculated using XRD is due to the fact that the particles are composed of several crystallization domains, which are observed using X-rays, while with SEM the whole particle is observed [37]. It is known that the shape of crystals is mostly controlled by the growth rates along different directions. Fig. 4 outlines the growth mode of the Fe3 O4 octahedron. It is known the morphology of crystal is mostly controlled by the ratio of the growth rate along different directions, and it has been proposed that a perfect octahedron formed when the ratio (R oct ) of growth rate along the <100> versus <111> direction is 1.73 [38]. In the reaction system, the concentration of NaOH plays an important role in the morphologies of Fe3 O4 . One the one hand, pure-phase Fe3 O4 particles can be synthesized under strong alkaline. One the other hand, when the solution PH value is greater than 13, the concentration of oxygen ion reaches a certain level, this will leads to the growth rate of <111> direction more rapidly than <100> direction [39]. In other words, the (111) crystal surface has higher surface energy. While, in the process of crystal growth, the reaction rate is also affect the growth rate of <100> and <111> direction. Mitra [40] pointed out that when the temperature is raised with a fast heating rate (10 ◦ C/min), result in nanoparticles possess a minimum surface energy. The surface energy (γ ) of different crystallographic planes is different, and for iron oxide the sequence is γ (111) < γ (001) < γ (101). Hence, the PG molecules selectively absorbed to (111) crystal surface which accelerate the growth of
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Fig. 3. SEM images of the synthesized Fe3 O4 : (a) PG; (b) Without PG.
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Fig. 4. Schematic illustration of the Growth Mode of the Fe3 O4 octahedra.
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Fig. 5. ZFC and FC curves of the synthesized Fe3 O4 under magnetic field of 1000 Oe: (a) PG; (b) Without PG.
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(100) crystal surface. Finally, the growth rate of <111> direction was slower than <100> direction, and the octahedron morphology was formed. So the obtained octahedral crystals can be formed. Zero-field-cooled (ZFC) and field-cooled (FC) magnetization curves of the Fe3 O4 particles are presented in Fig. 5. In the ZFC measurement, the Fe3 O4 products were cooled from 300 to 5 K without applying any external magnetic field. After reaching 5 K, 1000 Oe magnetic field was applied and the magnetization was measured as a function of temperature during heating. In the FC measurement, the magnetization of the Fe3 O4 products were measured during whole cooling procedure (300 to 5 K) under the magnetic field which was the same as applied in the ZFC measurement. It can be clearly seen that the ZFC magnetization increases
with increasing temperature and reaches a maximum at a temperature of 120 K. This specific temperature is called the Verwey transition temperature ( T v ) [41,42], where the magnetic easy axis switches from the <111> to <100> direction [38]. Below the transition temperature, the anisotropy energy is larger than the thermal fluctuations. When above this temperature, the anisotropy energy barrier is overcome by thermal energy and each magnetic moment fluctuates randomly, thus the total magnetization decreases with increasing temperature [36]. Moreover, the presence of the Verwey transition further indicates the high quality and high phase purity of the prepared Fe3 O4 . In addition, whether or not to add the PG, the change trend of the two curves is roughly consistent, the magnetization of the sample without PG is slightly higher than that exist the PG. It can be seen that the ZFC and FC magnetization curves show a distinct divergence below the irreversibility temperature ((a) ∼250 K, (b) ∼130 K). This indicates that part of total magnetization is frozen along the FC direction [43]. Magnetic property of the products were investigated in detail. The sample was measured by varying magnetic field and temperatures (5–300 K). As seen in the figure Fig. 6a, all of the magnetic hysteresis loops showed a strong magnetic response to the varying magnetic field. The presence of hysteresis loop at room temperature indicated that the products are ferromagnetic in nature. The value of saturation magnetization (M s ), remanence magnetization (M r ) and coercivity (H c ) were found to be 87.48 emu/g, 6.22 emu/g and 95.6 Oe, respectively. Yan et al. [24] had got Fe3 O4 solid spheres about 500 nm and hollow spheres about 300 nm, the value of M s are 72.6 and 64.9 emu/g, the value of H c are 5 and 48.3 Oe, respectively. All of them are lower than the Fe3 O4 octahedral particle in this study, indicating subdued surface disorder in octahedral geometry. In addition, there is a remarkable peak around 107 K in the ZFC curves of the hollow sample, which corre-
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Fig. 6. (a) Magnetic hysteresis loops of the synthesized Fe3 O4 measured at different temperatures; (b) Temperature dependence of the saturation magnetization (M s ) of the synthesized Fe3 O4 ; (c) Temperature dependence of the remanence magnetization (M r ) and reduced remanent magnetization (M r / M s ) of the synthesized Fe3 O4 ; (d) Temperature dependence of coercive field (H c ) of the synthesized Fe3 O4 .
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sponds to the blocking temperature T b . The value of M s decreased with the increasing of the test temperature, as seen in the figure Fig. 6b, which can be explained by the increasing strength of the exchange interaction between tetrahedral and octahedral sites with the decrease of temperature [44]. The value of M s at room temperature is lower than that of the bulk value of Fe3 O4 (92 emu/g), which can be mainly attributed to the particle size. The temperature dependence of M r , M r / M s and H c for the Fe3 O4 particles were given in Fig. 6c and d, respectively. As expected, M r , M r / M s and H c decreased with the increasing of the test temperature. According to the Stoner–Wohlfarth theory [45], the M r / M s values are lower than 0.5 in the inset of Fig. 6c, suggesting that the synthesized Fe3 O4 particles have uniaxial anisotropy. The presence of the uniaxial anisotropy observed in magnetic nanoparticles can be attributed to surface effects. It is consistent with the conclusion of the Fig. 2 and Fig. 4. The value of H c increased, resulting from a fact that the effective magnetic anisotropy increased with the decreasing of the test temperature [46,47].
4. Conclusions
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In summary, Fe3 O4 octahedral particles have been synthesized successfully by a simple hydrothermal route. The results showed that the resulting Fe3 O4 is of pure phase particles and the average edge length is about 500 nm. The existence of PG and heating rate (10 ◦ C/min) affect the ratio of the growth rate along the <111> versus the <100> direction, which further determines the morphology of the product. ZFC/FC results revealed that the T v value of the Fe3 O4 octahedral is 120 K. The existence of Verwey transition further suggested that the hydrothermal route is an efficient method to produce pure phase Fe3 O4 particles. The magnetic hysteresis loops revealed that the Fe3 O4 octahedral show high ferromagnetic property at room temperature with the M s of 87.48 emu/g and the H c of 95.6 Oe. M s , M r , M r / M s and H c decreased with the increase of the test temperature, suggesting that the synthesized Fe3 O4 particles have uniaxial anisotropy, and the effective magnetic anisotropy increased with the decrease of the test temperature.
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Acknowledgements
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This work is supported by Natural Science Foundation of China (Nos. 11374204, 11674215, 51402186), “ShuGuang” project of Shanghai Municipal Education Commission and Shanghai Education Development Foundation (No. 13SG52), and Projects of Science and Technology Commission of Shanghai Municipality (No. 14520501000).
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References
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[1] M. Cavas, R.K. Gupta, Ahmed A. Al-Ghamdi, Zarah H. Gafer, Farid El-Tantawy, F. Yakuphanoglu, Preparation and characterization of dye sensitized solar cell based on nanostructured Fe2 O3 , Mater. Lett. 105 (2013) 106–109. [2] R.K. Gupta, K. Ghosh, R. Patel, P.K. Kahol, A novel method to synthesis iron oxide thin films, J. Alloys Compd. 509 (2011) 7529–7531. [3] R.K. Gupta, K. Ghosh, L. Dong, P.K. Kahol, Structural and magnetic properties of phase controlled iron oxide rods, Mater. Lett. 65 (2011) 225–228. [4] L. Donaldson, New storage platforms from spin ice, Mater. Today 15 (2012) 187. [5] J.H. Meng, G.Q. Yang, L.M. Yan, X.Y. Wang, Synthesis and characterization of magnetic nanometer pigment Fe3 O4 , Dyes Pigments 66 (2005) 109–113. [6] Y.T. Zhang, D. Li, M. Yu, W.F. Ma, J. Guo, C.C. Wang, Fe3 O4 /PVIM-Ni2+ magnetic composite microspheres for highly specific separation of histidine-rich proteins, ACS Appl. Mater. Interfaces 6 (2014) 8836–8844. [7] M. Hałupka-Bryl, M. Bednarowicz, B. Dobosz, R. Krzyminiewski, T. Zalewski, B. ´ Wereszczynska, G. Nowaczyk, M. Jarek, Y. Nagasaki, Doxorubicin loaded PEG-bpoly (4-vinylbenzylphosphonate) coated magnetic iron oxide nanoparticles for targeted drug delivery, J. Magn. Magn. Mater. 386 (2015) 320–327. [8] S.I. Evsin, N.A. Sokolov, Y.I. Stradomsky, V.B. Charkovsky, Development of magnetic fluid reciprocating motion seals, J. Magn. Magn. Mater. 1–3 (1990) 253–256. [9] K.K. Cheng, P.S. Chan, S.J. Fan, S.M. Kwan, K.L. Yeung, Y.J. Wáng, A.H.L. Chow, E.X. Wu, L. Baum, Curcumin-conjugated magnetic nanoparticles for detecting amyloid plaques in Alzheimer’s disease mice using magnetic resonance imaging (MRI), Biomaterials 44 (2015) 155–172. [10] H.T. Jeng, G.Y. Guo, D.J. Huang, Charge-orbital ordering and Verwey transition in magnetite, Phys. Rev. Lett. 93 (2004) 156403. [11] A. Jafari, S. Farjami Shayesteh, M. Salouti, K. Boustani, Effect of annealing temperature on magnetic phase transition in Fe3 O4 nanoparticles, J. Magn. Magn. Mater. 379 (2015) 305–312. [12] Z.H. Xu, S.L. Gu, S.M. Huang, K. Tang, J.D. Ye, S.M. Zhu, M.X. Xu, Y.D. Zheng, Structure and properties of Fe3 O4 films grown on ZnO template via metal organic chemical vapor deposition, J. Magn. Magn. Mater. 385 (2015) 257–264. [13] D.J. Craik, Magnetic Oxides, A Wiley-Interscience Publication, John Wiley and Sons, New York, 1975. [14] F. Shabani, A. Khodayari, Structural, compositional, and biological characterization of Fe3 O4 nanoparticles synthesized by hydrothermal method, synthesis and reactivity in inorganic, Synth. React. Inorg. Metl.-Org. Nano.-Metal. Chem. 45 (2015) 356–362. [15] X.D. Liu, H. Chen, S.S. Liu, L.Q. Ye, Y.P. Li, Hydrothermal synthesis of superparamagnetic Fe3 O4 nanoparticles with ionic liquids as stabilizer, Mater. Res. Bull. 62 (2015) 217–221. [16] F.X. Chen, S.L. Xie, J.H. Zhang, R. Liu, Synthesis of spherical Fe3 O4 magnetic nanoparticles by co-precipitation in choline chloride/urea deep eutectic solvent, Mater. Lett. 112 (2013) 177–179. [17] H.T. Cui, Y. Liu, W.Z. Ren, Structure switch between α -Fe2 O3 , γ -Fe2 O3 and Fe3 O4 during the large scale and low temperature sol–gel synthesis of nearly monodispersed iron oxide nanoparticles, Adv. Powder Technol. 24 (2013) 93–97. [18] K. Chinnaraj, A. Manikandan, P. Ramu, S. Arul Antony, P. Neeraja, Comparative studies of microwave- and sol–gel-assisted combustion methods of Fe3 O4 nanostructures: structural, morphological, optical, magnetic, and catalytic properties, J. Supercond. Nov. Magn. 28 (2015) 179–190. [19] Y.F. Li, R.L. Jiang, T.Y. Liu, H. Lv, L. Zhou, X.Y. Zhang, One-pot synthesis of grass-like Fe3O4 nanostructures by a novel microemulsion-assisted solvothermal method, Ceram. Int. 40 (2014) 1059–1063. [20] Z. Fekri Leila, N. Mohammad, H. Pour Keyhan, Green aqueous synthesis of mono, bis and trisdihydropyridines using nano Fe3 O4 under ultrasound irradiation, Curr. Org. Synth. 12 (2015) 76–79. [21] J.H. Yang, B. Ramaraj Kuk Ro Yoon, Preparation and characterization of superparamagnetic graphene oxide nanohybrids anchored with Fe3 O4 nanoparticles, J. Alloys Compd. 583 (2014) 128–133.
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[22] Z.P. Cheng, X.Z. Chu, J.Z. Yin, H. Zhong, J.M. Xu, Surfactantless synthesis of Fe3 O4 magnetic nanobelts by a simple hydrothermal process, Mater. Lett. 75 (2012) 172–174. [23] Y. Takeno, Yasukazu Murakami, Takeshi Sato, Toshiaki Tanigaki, Hyun Soon Park, Daisuke Shindo, R. Matthew Ferguson, Kannan M. Krishnan, Morphology and magnetic flux distribution in superparamagnetic, single-crystalline Fe3 O4 nanoparticle rings, Appl. Phys. Lett. 105 (2014) 183102. [24] S.J. Yan, J.K. Tang, P. Liu, Q. Gao, G.Y. Hong, L. Zhen, The influence of hollow structure on the magnetic characteristics for Fe3 O4 submicron spheres, J. Appl. Phys. 109 (2011), 07B535. [25] T. Han, X.Z. Jin, C.Y. Li, L.X. Zhang, Y.S. Lei, One-pot hydrothermal synthesis and magnetic properties of octahedral and clover-structured Fe3 O4 by a Ce cationassisted route, Mater. Lett. 92 (2013) 184–187. [26] E. Mitchell, F. De Souza, R.K. Gupta, P.K. Kahol, D. Kumar, L. Dong, Bipin Kumar Gupta, Probing on the hydrothermally synthesized iron oxide nanoparticles for ultra-capacitor applications, Powder Technol. 272 (2015) 295–299. [27] Y.S. Liu, Y.B. Zhong, J.C. Zhang, Z.M. Ren, S.X. Cao, Z.L. Yang, T. Gao, Structure and magnetic properties of MnZn nanoferrites synthesized under a high magnetic field, J. Appl. Phys. 110 (2011) 074310. [28] Y.S. Liu, J.C. Zhang, Y.Q. Wang, Y.Y. Zhu, Z.L. Yang, J. Chen, S.X. Cao, Weak exchange effect and large refrigerant capacity in a bulk metallic glass Gd0.32 Tb0.26 Co0.20 Al0.22 , Appl. Phys. Lett. 94 (2009) 112507. [29] X.D. Si, Y.S. Liu, X.F. Wu, W. Lei, J. Lin, T. Gao, L. Zheng, Al–Mg co-doping effect on optical and magnetic properties of ZnO nanopowders, Phys. Lett. A 379 (2015) 1445. [30] Y.B. Khollam, S.R. Dhage, Microwave hydrothermal preparation of submicronsized spherical magnetite (Fe3 O4 ) powders, Mater. Lett. 56 (2002) 571–577. [31] B. Greta, M. Risti, I. Nowik, et al., Formation of nanocrystallinemag-netite by thermal decomposition of iron choline citrate, J. Alloys Compd. 334 (2002) 304–312. [32] Elias Mitchell, Ram K. Gupta, Kwadwo Mensah-Darkwa, Dhananjay Kumar, Karthik Ramasamy, Bipin K. Gupta, Pawan Kahol, Facile synthesis and morphogenesis of superparamagnetic iron oxide nanoparticles for high-performance supercapacitor applications, New J. Chem. 38 (2014) 4344–4350. [33] R.D. Waldron, Infrared spectra of ferrites, Phys. Rev. 99 (1955) 1727–1735. [34] Z.J. Zhang, X.Y. Chen, B.N. Wang, C.W. Shi, Hydrothermal synthesis and selfassembly of magnetite (Fe3 O4 ) nanoparticles with the magnetic and electrochemical properties, J. Cryst. Growth 310 (2008) 5453–5457. [35] A. Jafari, S. Farjami Shayesteh, M. Salouti, K. Boustani, Effect of annealing temperature on magnetic phase transition in Fe3O4 nanoparticles, J. Magn. Magn. Mater. 379 (2015) 305–312. [36] A. Demir, R. Topkaya, A. Baykal, Green synthesis of superparamagnetic Fe3 O4 nanoparticles with maltose: its magnetic investigation, Polyhedron 65 (2013) 282–287. [37] R.K. Gupta, K. Ghosh, L. Dong, P.K. Kahol, Structural and magnetic properties of nanostructured iron oxide, Physica E 43 (2011) 1095–1098. [38] B.Y. Geng, J.Z. Ma, J.H. You, Controllable synthesis of single-crystalline Fe3 O4 polyhedral possessing the active basal facets, Cryst. Growth Des. 8 (2008) 1443–1447. [39] Arijit Mitra, J. Mohapatra, S.S. Meena, C.V. Tomy, M. Aslam, Verwey transition in ultrasmall-sized octahedral Fe3 O4 nanoparticles, J. Phys. Chem. C 118 (2014) 19356–19362. [40] E.J.W. Verwey, Electronic conduction of magnetite (Fe3 O4 ) and its transition point at low temperatures, Nature (London) 144 (1939) 327. [41] H. Seo, Masao Ogata, H. Fukuyama, Theory of the Verwey transition in Fe3 O4 , Physica B 329–333 (2003) 932–933. [42] Q.H. Wang, D. Chen, J. Chen, C. Lai, L. Li, C. Wang, Facile synthesis and electrochemical properties of Fe3 O4 hexahedra for Li-ion battery anode, Mater. Lett. 141 (2015) 319–322. [43] Z.H. Zhou, J.M. Xue, H.S.O. Chan, J. Wang, Transparent magnetic composites of ZnFe2 O4 nanoparticles in silica, J. Appl. Phys. 90 (2001) 4169. [44] R.K. Gupta, K. Ghosh, P.K. Kahol, Vertical exchange bias effects in multilayer thin films based on iron oxide and chromium oxide, Mater. Lett. 65 (2011) 2429–2431. [45] E.C. Stoner, E.P. Wohlfarth, A mechanism of magnetic hysteresis in heterogeneous alloys, Philos. Trans. R. Soc. Lond. A 240 (826) (1948) 599. [46] G. Ennas, A. Musinu, G. Piccaluga, D. Zedda, Characterization of iron oxide nanoparticles in an Fe2 O3 –SiO2 composite prepared by a sol–gel method, Chem. Mater. 10 (1998) 495–502. [47] A. Vincenzo, R. Pietro, P. Stefano, Magnetic iro oxide nanoparticles with tunable size and free surface obtained via a “green” approach based on laser irradiation in water, J. Mater. Chem. 21 (2011) 18665.
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Synthesis and magnetic properties of octahedral Fe3 O4 via a one-pot hydrothermal route
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Article history: Received 6 May 2016 Received in revised form 12 September 2016 Accepted 16 September 2016 Available online xxxx Communicated by R. Wu Keywords: Fe3 O4 Hydrothermal synthesis Octahedra Magnetic properties
Magnetite (Fe3 O4 ) particles were prepared by a facile one-step hydrothermal method in assistant of α -Propylene glycol solution (PG). The X-ray diffraction (XRD), FT–IR analysis and the Verwey transition confirmed that as-prepared magnetite particles were pure spinel Fe3 O4 without any impurity. Scanning electron microscopy (SEM) showed that the particles have octahedral morphology and the average edge length of these octahedra was about 500 nm. The shape of crystals can be controlled by the growth rates along different directions, and the growth mode of the Fe3 O4 octahedron was outlined. The magnetic measurement at room temperature suggested that the saturation magnetization (M s ) and coercivity (H c ) were 87.48 emu/g and 95.6 Oe, respectively. Fe3 O4 nanoparticles showed a sharp transition (Verwey transition) at around 120 K, where the magnetic easy axis switches from the <111> to <100> direction. The value of H c decreased with the increase of the test temperature, resulting from a fact that the effective magnetic anisotropy decreased with the increase of the test temperature. © 2016 Published by Elsevier B.V.
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1. Introduction
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Different forms of iron oxide such as magnetite (Fe3 O4 ), maghemite (γ -Fe2 O3 ) and hematite (α -Fe3 O4 ) are technologically very important [1–3]. Magnetic materials have been extensively studied in the last 50 years, among them, Fe3 O4 is one of the representative magnetic materials and has elicited increasing interests due to its environmental friendly, interesting magnetic behaviors, and potential applications in areas such as magnetic storage devices, electro-photo graphic developer, pigment, protein separation, drug delivery, dynamic sealing, and magnetic resonance images (MRI) [4–9]. Fe3 O4 possesses an inverse spinel structure with a +3 chemical formula FeA [Fe+2 Fe+3 ]B O4 [10,11], in which A sites (tetrahedral sites) are occupied by Fe3+ and B sites (octahedral sites) are occupied by equal numbers of Fe2+ and Fe3+ . At temperature below the Curie point (∼860 K), Fe3 O4 is ferromagnetic with the A-site moments aligned antiparallel to the B-sites and has spontaneous magnetization [12,13]. The nature of ferromagnetic materials is determined by many factors, such as saturation magnetization is an intrinsic property of ferromagnetic, it is not only independent of temperature but also dependent of particle size and morphology [14]. While, the size and morphology of the particle are mainly determined by the preparation process.
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Corresponding author. Fax: +86 21 68025889. E-mail address: [email protected] (Y. Liu).
http://dx.doi.org/10.1016/j.physleta.2016.09.018 0375-9601/© 2016 Published by Elsevier B.V.
During the last few years, various synthetic approaches have been used for the preparation of magnetic Fe3 O4 , such as hydrothermal process [15], co-precipitation method [16], sol–gel route [17], microwave synthesis [18], microemulsion method [19], and ultrasound irradiation [20]. The resulting Fe3 O4 showed various morphologies, for example, particles [21], belts [22], rings [23], and hollow spheres [24]. Among these methods, the hydrothermal method is particularly attractive because of several advantages: (1) resulting materials in a good crystallinity and particle size; (2) economic and environmental friendly; (3) controllable morphologies [25,26]. In our previous papers [27–29], nano-structure, DMSs, magnetic properties, and magnetocaloric effect have been investigated in Mn–Zn nano-ferrite, Co bulk metallic glass and Mg– Al co-doped ZnO, and some results have been obtained. In this work, we synthesized octahedral Fe3 O4 by a facile one-step hydrothermal method in assistant with PG. The structural and magnetic properties of the resulting Fe3 O4 have been investigated in detail.
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2. Experimental section
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All reagents were analytical grade and used as received without further purification. In a typical synthetic procedure, 0.328 g of FeSO4 ·7H2 O was dissolved in 10 mL of deionized water, subsequently, it was slowly dropped into the 22 mL of PG by drop.
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Fig. 1. XRD pattern of the synthesized Fe3 O4 : (a) PG; (b) Without PG.
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In addition, the mixed solution was stirring for 1 h. Then 1.6 g of NaOH was added. The mixture was stirred for another 10 min allowing the formation of a homogeneous solution, subsequently it was transferred into a 50 mL Teflon-lined stainless steel autoclave, sealed, then heat up to 200 ◦ C at a speed of 10 ◦ C/min and maintained at 200 ◦ C for 20 h. After the reaction, the autoclave was naturally cooled to room temperature. A black solid was collected by centrifugation and washed three times with deionized water and anhydrous ethanol, respectively. Then, the products were dried under vacuum at 60 ◦ C for 12 h.
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The resulting samples was characterized by a X-ray power diffraction (XRD, Bruker-Axs, D8 Advance) with Cu Kα radiation (λ = 1.5406 Å). Morphology of the samples was examined by a scanning electron microscopy (SEM, XL30 S-FEG). The optical property was characterized by an infrared spectrometer (SHIMADZU FTIR-8400S). Magnetic measurement was performed by a physical properties measurement system (PPMS/Quantum Design).
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Fig. 1 shows the XRD pattern of the products. All the diffraction peaks of the sample can be indexed to a cubic phase (fcc, space group Fd-3 m) of magnetite structure according to JCPDS card No. 89-0688 and No. 76-1849. The lattice constants were a(PG) = 8.405 Å, a(without PG) = 8.400 Å. It is agreement with the literature [30,31], which the value is 8.337∼8.419 Å. No peaks assigned to hematite, metal hydroxides, or other impurities were detected, indicating high purity and crystallinity of the sample. Therefore, we can know that whether PG was added into the reaction system or not, the products were pure face-centered cubic phase of Fe3 O4 . According to Debye–Scherrer formula [32], take the half peak width of 2 theta = 35.4 degrees, the average gain size of Fe3 O4 particles are 71.67 and 91.59 nm. It is worth noting that the intensity ratios of the (111)/(400) peaks for the Fig. 1(a) and (b) are 0.3 and 0.48, respectively. Indicating that the growth rate of <111> direction becomes slower, after the PG was added. The products were examined by FT–IR to ascertain its chemical composition. The FT–IR spectrum was shown in Fig. 2. A band at about 583 and 456 cm−1 attributed to the intrinsic stretching vibrations of the metal at tetrahedral site (Fetetra ↔ O) and octahedral site (Feocta ↔ O) [33], indicating that pure-phase Fe3 O4 was synthesized successfully whether PG was added into the reaction
Fig. 2. FT–IR spectra of the synthesized Fe3 O4 : (a) PG; (b) Without PG.
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system or not. Meanwhile, a broad characteristic band at around 3460 cm−1 is attributed to the stretching modes of H2 O molecules or –OH groups on the surface of magnetite particles. A band at around 1635 cm−1 can be assigned to the bending vibrations of H2 O [34,35]. In the curve of Fig. 2(a), the peaks at around 2851 and 1428 cm−1 are corresponded to the bond stretching vibration and bending vibration of C–H in –CH2 , respectively. The absorption peak near 1100 cm−1 is corresponded to the bond stretching vibration of C–O, which is consistent with C–O–C and C–O–H in PG [36]. The offset of the Fe–O peaks shows that there are some interactions between PG molecules and Fe3 O4 crystal. The morphology of the products were characterized by SEM. Fig. 3a and 3b display the SEM images of the Fe3 O4 particles synthesized in the PG and without PG. As observed in two images, the Fe3 O4 particles synthesized in the PG is relatively uniform octahedral morphology. While, in the absence of PG, the Fe3 O4 particles synthesized is disorder. The average edge length of these octahedra was measured to be about 500 nm. The difference between the particle size obtained by SEM and the crystallite size calculated using XRD is due to the fact that the particles are composed of several crystallization domains, which are observed using X-rays, while with SEM the whole particle is observed [37]. It is known that the shape of crystals is mostly controlled by the growth rates along different directions. Fig. 4 outlines the growth mode of the Fe3 O4 octahedron. It is known the morphology of crystal is mostly controlled by the ratio of the growth rate along different directions, and it has been proposed that a perfect octahedron formed when the ratio (R oct ) of growth rate along the <100> versus <111> direction is 1.73 [38]. In the reaction system, the concentration of NaOH plays an important role in the morphologies of Fe3 O4 . One the one hand, pure-phase Fe3 O4 particles can be synthesized under strong alkaline. One the other hand, when the solution PH value is greater than 13, the concentration of oxygen ion reaches a certain level, this will leads to the growth rate of <111> direction more rapidly than <100> direction [39]. In other words, the (111) crystal surface has higher surface energy. While, in the process of crystal growth, the reaction rate is also affect the growth rate of <100> and <111> direction. Mitra [40] pointed out that when the temperature is raised with a fast heating rate (10 ◦ C/min), result in nanoparticles possess a minimum surface energy. The surface energy (γ ) of different crystallographic planes is different, and for iron oxide the sequence is γ (111) < γ (001) < γ (101). Hence, the PG molecules selectively absorbed to (111) crystal surface which accelerate the growth of
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Fig. 5. ZFC and FC curves of the synthesized Fe3 O4 under magnetic field of 1000 Oe: (a) PG; (b) Without PG.
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(100) crystal surface. Finally, the growth rate of <111> direction was slower than <100> direction, and the octahedron morphology was formed. So the obtained octahedral crystals can be formed. Zero-field-cooled (ZFC) and field-cooled (FC) magnetization curves of the Fe3 O4 particles are presented in Fig. 5. In the ZFC measurement, the Fe3 O4 products were cooled from 300 to 5 K without applying any external magnetic field. After reaching 5 K, 1000 Oe magnetic field was applied and the magnetization was measured as a function of temperature during heating. In the FC measurement, the magnetization of the Fe3 O4 products were measured during whole cooling procedure (300 to 5 K) under the magnetic field which was the same as applied in the ZFC measurement. It can be clearly seen that the ZFC magnetization increases
with increasing temperature and reaches a maximum at a temperature of 120 K. This specific temperature is called the Verwey transition temperature ( T v ) [41,42], where the magnetic easy axis switches from the <111> to <100> direction [38]. Below the transition temperature, the anisotropy energy is larger than the thermal fluctuations. When above this temperature, the anisotropy energy barrier is overcome by thermal energy and each magnetic moment fluctuates randomly, thus the total magnetization decreases with increasing temperature [36]. Moreover, the presence of the Verwey transition further indicates the high quality and high phase purity of the prepared Fe3 O4 . In addition, whether or not to add the PG, the change trend of the two curves is roughly consistent, the magnetization of the sample without PG is slightly higher than that exist the PG. It can be seen that the ZFC and FC magnetization curves show a distinct divergence below the irreversibility temperature ((a) ∼250 K, (b) ∼130 K). This indicates that part of total magnetization is frozen along the FC direction [43]. Magnetic property of the products were investigated in detail. The sample was measured by varying magnetic field and temperatures (5–300 K). As seen in the figure Fig. 6a, all of the magnetic hysteresis loops showed a strong magnetic response to the varying magnetic field. The presence of hysteresis loop at room temperature indicated that the products are ferromagnetic in nature. The value of saturation magnetization (M s ), remanence magnetization (M r ) and coercivity (H c ) were found to be 87.48 emu/g, 6.22 emu/g and 95.6 Oe, respectively. Yan et al. [24] had got Fe3 O4 solid spheres about 500 nm and hollow spheres about 300 nm, the value of M s are 72.6 and 64.9 emu/g, the value of H c are 5 and 48.3 Oe, respectively. All of them are lower than the Fe3 O4 octahedral particle in this study, indicating subdued surface disorder in octahedral geometry. In addition, there is a remarkable peak around 107 K in the ZFC curves of the hollow sample, which corre-
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Fig. 6. (a) Magnetic hysteresis loops of the synthesized Fe3 O4 measured at different temperatures; (b) Temperature dependence of the saturation magnetization (M s ) of the synthesized Fe3 O4 ; (c) Temperature dependence of the remanence magnetization (M r ) and reduced remanent magnetization (M r / M s ) of the synthesized Fe3 O4 ; (d) Temperature dependence of coercive field (H c ) of the synthesized Fe3 O4 .
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sponds to the blocking temperature T b . The value of M s decreased with the increasing of the test temperature, as seen in the figure Fig. 6b, which can be explained by the increasing strength of the exchange interaction between tetrahedral and octahedral sites with the decrease of temperature [44]. The value of M s at room temperature is lower than that of the bulk value of Fe3 O4 (92 emu/g), which can be mainly attributed to the particle size. The temperature dependence of M r , M r / M s and H c for the Fe3 O4 particles were given in Fig. 6c and d, respectively. As expected, M r , M r / M s and H c decreased with the increasing of the test temperature. According to the Stoner–Wohlfarth theory [45], the M r / M s values are lower than 0.5 in the inset of Fig. 6c, suggesting that the synthesized Fe3 O4 particles have uniaxial anisotropy. The presence of the uniaxial anisotropy observed in magnetic nanoparticles can be attributed to surface effects. It is consistent with the conclusion of the Fig. 2 and Fig. 4. The value of H c increased, resulting from a fact that the effective magnetic anisotropy increased with the decreasing of the test temperature [46,47].
4. Conclusions
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In summary, Fe3 O4 octahedral particles have been synthesized successfully by a simple hydrothermal route. The results showed that the resulting Fe3 O4 is of pure phase particles and the average edge length is about 500 nm. The existence of PG and heating rate (10 ◦ C/min) affect the ratio of the growth rate along the <111> versus the <100> direction, which further determines the morphology of the product. ZFC/FC results revealed that the T v value of the Fe3 O4 octahedral is 120 K. The existence of Verwey transition further suggested that the hydrothermal route is an efficient method to produce pure phase Fe3 O4 particles. The magnetic hysteresis loops revealed that the Fe3 O4 octahedral show high ferromagnetic property at room temperature with the M s of 87.48 emu/g and the H c of 95.6 Oe. M s , M r , M r / M s and H c decreased with the increase of the test temperature, suggesting that the synthesized Fe3 O4 particles have uniaxial anisotropy, and the effective magnetic anisotropy increased with the decrease of the test temperature.
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JID:PLA AID:24070 /DIS Doctopic: Nanoscience
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Acknowledgements
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This work is supported by Natural Science Foundation of China (Nos. 11374204, 11674215, 51402186), “ShuGuang” project of Shanghai Municipal Education Commission and Shanghai Education Development Foundation (No. 13SG52), and Projects of Science and Technology Commission of Shanghai Municipality (No. 14520501000).
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References
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[1] M. Cavas, R.K. Gupta, Ahmed A. Al-Ghamdi, Zarah H. Gafer, Farid El-Tantawy, F. Yakuphanoglu, Preparation and characterization of dye sensitized solar cell based on nanostructured Fe2 O3 , Mater. Lett. 105 (2013) 106–109. [2] R.K. Gupta, K. Ghosh, R. Patel, P.K. Kahol, A novel method to synthesis iron oxide thin films, J. Alloys Compd. 509 (2011) 7529–7531. [3] R.K. Gupta, K. Ghosh, L. Dong, P.K. Kahol, Structural and magnetic properties of phase controlled iron oxide rods, Mater. Lett. 65 (2011) 225–228. [4] L. Donaldson, New storage platforms from spin ice, Mater. Today 15 (2012) 187. [5] J.H. Meng, G.Q. Yang, L.M. Yan, X.Y. Wang, Synthesis and characterization of magnetic nanometer pigment Fe3 O4 , Dyes Pigments 66 (2005) 109–113. [6] Y.T. Zhang, D. Li, M. Yu, W.F. Ma, J. Guo, C.C. Wang, Fe3 O4 /PVIM-Ni2+ magnetic composite microspheres for highly specific separation of histidine-rich proteins, ACS Appl. Mater. Interfaces 6 (2014) 8836–8844. [7] M. Hałupka-Bryl, M. Bednarowicz, B. Dobosz, R. Krzyminiewski, T. Zalewski, B. ´ Wereszczynska, G. Nowaczyk, M. Jarek, Y. Nagasaki, Doxorubicin loaded PEG-bpoly (4-vinylbenzylphosphonate) coated magnetic iron oxide nanoparticles for targeted drug delivery, J. Magn. Magn. Mater. 386 (2015) 320–327. [8] S.I. Evsin, N.A. Sokolov, Y.I. Stradomsky, V.B. Charkovsky, Development of magnetic fluid reciprocating motion seals, J. Magn. Magn. Mater. 1–3 (1990) 253–256. [9] K.K. Cheng, P.S. Chan, S.J. Fan, S.M. Kwan, K.L. Yeung, Y.J. Wáng, A.H.L. Chow, E.X. Wu, L. Baum, Curcumin-conjugated magnetic nanoparticles for detecting amyloid plaques in Alzheimer’s disease mice using magnetic resonance imaging (MRI), Biomaterials 44 (2015) 155–172. [10] H.T. Jeng, G.Y. Guo, D.J. Huang, Charge-orbital ordering and Verwey transition in magnetite, Phys. Rev. Lett. 93 (2004) 156403. [11] A. Jafari, S. Farjami Shayesteh, M. Salouti, K. Boustani, Effect of annealing temperature on magnetic phase transition in Fe3 O4 nanoparticles, J. Magn. Magn. Mater. 379 (2015) 305–312. [12] Z.H. Xu, S.L. Gu, S.M. Huang, K. Tang, J.D. Ye, S.M. Zhu, M.X. Xu, Y.D. Zheng, Structure and properties of Fe3 O4 films grown on ZnO template via metal organic chemical vapor deposition, J. Magn. Magn. Mater. 385 (2015) 257–264. [13] D.J. Craik, Magnetic Oxides, A Wiley-Interscience Publication, John Wiley and Sons, New York, 1975. [14] F. Shabani, A. Khodayari, Structural, compositional, and biological characterization of Fe3 O4 nanoparticles synthesized by hydrothermal method, synthesis and reactivity in inorganic, Synth. React. Inorg. Metl.-Org. Nano.-Metal. Chem. 45 (2015) 356–362. [15] X.D. Liu, H. Chen, S.S. Liu, L.Q. Ye, Y.P. Li, Hydrothermal synthesis of superparamagnetic Fe3 O4 nanoparticles with ionic liquids as stabilizer, Mater. Res. Bull. 62 (2015) 217–221. [16] F.X. Chen, S.L. Xie, J.H. Zhang, R. Liu, Synthesis of spherical Fe3 O4 magnetic nanoparticles by co-precipitation in choline chloride/urea deep eutectic solvent, Mater. Lett. 112 (2013) 177–179. [17] H.T. Cui, Y. Liu, W.Z. Ren, Structure switch between α -Fe2 O3 , γ -Fe2 O3 and Fe3 O4 during the large scale and low temperature sol–gel synthesis of nearly monodispersed iron oxide nanoparticles, Adv. Powder Technol. 24 (2013) 93–97. [18] K. Chinnaraj, A. Manikandan, P. Ramu, S. Arul Antony, P. Neeraja, Comparative studies of microwave- and sol–gel-assisted combustion methods of Fe3 O4 nanostructures: structural, morphological, optical, magnetic, and catalytic properties, J. Supercond. Nov. Magn. 28 (2015) 179–190. [19] Y.F. Li, R.L. Jiang, T.Y. Liu, H. Lv, L. Zhou, X.Y. Zhang, One-pot synthesis of grass-like Fe3O4 nanostructures by a novel microemulsion-assisted solvothermal method, Ceram. Int. 40 (2014) 1059–1063. [20] Z. Fekri Leila, N. Mohammad, H. Pour Keyhan, Green aqueous synthesis of mono, bis and trisdihydropyridines using nano Fe3 O4 under ultrasound irradiation, Curr. Org. Synth. 12 (2015) 76–79. [21] J.H. Yang, B. Ramaraj Kuk Ro Yoon, Preparation and characterization of superparamagnetic graphene oxide nanohybrids anchored with Fe3 O4 nanoparticles, J. Alloys Compd. 583 (2014) 128–133.
5
[22] Z.P. Cheng, X.Z. Chu, J.Z. Yin, H. Zhong, J.M. Xu, Surfactantless synthesis of Fe3 O4 magnetic nanobelts by a simple hydrothermal process, Mater. Lett. 75 (2012) 172–174. [23] Y. Takeno, Yasukazu Murakami, Takeshi Sato, Toshiaki Tanigaki, Hyun Soon Park, Daisuke Shindo, R. Matthew Ferguson, Kannan M. Krishnan, Morphology and magnetic flux distribution in superparamagnetic, single-crystalline Fe3 O4 nanoparticle rings, Appl. Phys. Lett. 105 (2014) 183102. [24] S.J. Yan, J.K. Tang, P. Liu, Q. Gao, G.Y. Hong, L. Zhen, The influence of hollow structure on the magnetic characteristics for Fe3 O4 submicron spheres, J. Appl. Phys. 109 (2011), 07B535. [25] T. Han, X.Z. Jin, C.Y. Li, L.X. Zhang, Y.S. Lei, One-pot hydrothermal synthesis and magnetic properties of octahedral and clover-structured Fe3 O4 by a Ce cationassisted route, Mater. Lett. 92 (2013) 184–187. [26] E. Mitchell, F. De Souza, R.K. Gupta, P.K. Kahol, D. Kumar, L. Dong, Bipin Kumar Gupta, Probing on the hydrothermally synthesized iron oxide nanoparticles for ultra-capacitor applications, Powder Technol. 272 (2015) 295–299. [27] Y.S. Liu, Y.B. Zhong, J.C. Zhang, Z.M. Ren, S.X. Cao, Z.L. Yang, T. Gao, Structure and magnetic properties of MnZn nanoferrites synthesized under a high magnetic field, J. Appl. Phys. 110 (2011) 074310. [28] Y.S. Liu, J.C. Zhang, Y.Q. Wang, Y.Y. Zhu, Z.L. Yang, J. Chen, S.X. Cao, Weak exchange effect and large refrigerant capacity in a bulk metallic glass Gd0.32 Tb0.26 Co0.20 Al0.22 , Appl. Phys. Lett. 94 (2009) 112507. [29] X.D. Si, Y.S. Liu, X.F. Wu, W. Lei, J. Lin, T. Gao, L. Zheng, Al–Mg co-doping effect on optical and magnetic properties of ZnO nanopowders, Phys. Lett. A 379 (2015) 1445. [30] Y.B. Khollam, S.R. Dhage, Microwave hydrothermal preparation of submicronsized spherical magnetite (Fe3 O4 ) powders, Mater. Lett. 56 (2002) 571–577. [31] B. Greta, M. Risti, I. Nowik, et al., Formation of nanocrystallinemag-netite by thermal decomposition of iron choline citrate, J. Alloys Compd. 334 (2002) 304–312. [32] Elias Mitchell, Ram K. Gupta, Kwadwo Mensah-Darkwa, Dhananjay Kumar, Karthik Ramasamy, Bipin K. Gupta, Pawan Kahol, Facile synthesis and morphogenesis of superparamagnetic iron oxide nanoparticles for high-performance supercapacitor applications, New J. Chem. 38 (2014) 4344–4350. [33] R.D. Waldron, Infrared spectra of ferrites, Phys. Rev. 99 (1955) 1727–1735. [34] Z.J. Zhang, X.Y. Chen, B.N. Wang, C.W. Shi, Hydrothermal synthesis and selfassembly of magnetite (Fe3 O4 ) nanoparticles with the magnetic and electrochemical properties, J. Cryst. Growth 310 (2008) 5453–5457. [35] A. Jafari, S. Farjami Shayesteh, M. Salouti, K. Boustani, Effect of annealing temperature on magnetic phase transition in Fe3O4 nanoparticles, J. Magn. Magn. Mater. 379 (2015) 305–312. [36] A. Demir, R. Topkaya, A. Baykal, Green synthesis of superparamagnetic Fe3 O4 nanoparticles with maltose: its magnetic investigation, Polyhedron 65 (2013) 282–287. [37] R.K. Gupta, K. Ghosh, L. Dong, P.K. Kahol, Structural and magnetic properties of nanostructured iron oxide, Physica E 43 (2011) 1095–1098. [38] B.Y. Geng, J.Z. Ma, J.H. You, Controllable synthesis of single-crystalline Fe3 O4 polyhedral possessing the active basal facets, Cryst. Growth Des. 8 (2008) 1443–1447. [39] Arijit Mitra, J. Mohapatra, S.S. Meena, C.V. Tomy, M. Aslam, Verwey transition in ultrasmall-sized octahedral Fe3 O4 nanoparticles, J. Phys. Chem. C 118 (2014) 19356–19362. [40] E.J.W. Verwey, Electronic conduction of magnetite (Fe3 O4 ) and its transition point at low temperatures, Nature (London) 144 (1939) 327. [41] H. Seo, Masao Ogata, H. Fukuyama, Theory of the Verwey transition in Fe3 O4 , Physica B 329–333 (2003) 932–933. [42] Q.H. Wang, D. Chen, J. Chen, C. Lai, L. Li, C. Wang, Facile synthesis and electrochemical properties of Fe3 O4 hexahedra for Li-ion battery anode, Mater. Lett. 141 (2015) 319–322. [43] Z.H. Zhou, J.M. Xue, H.S.O. Chan, J. Wang, Transparent magnetic composites of ZnFe2 O4 nanoparticles in silica, J. Appl. Phys. 90 (2001) 4169. [44] R.K. Gupta, K. Ghosh, P.K. Kahol, Vertical exchange bias effects in multilayer thin films based on iron oxide and chromium oxide, Mater. Lett. 65 (2011) 2429–2431. [45] E.C. Stoner, E.P. Wohlfarth, A mechanism of magnetic hysteresis in heterogeneous alloys, Philos. Trans. R. Soc. Lond. A 240 (826) (1948) 599. [46] G. Ennas, A. Musinu, G. Piccaluga, D. Zedda, Characterization of iron oxide nanoparticles in an Fe2 O3 –SiO2 composite prepared by a sol–gel method, Chem. Mater. 10 (1998) 495–502. [47] A. Vincenzo, R. Pietro, P. Stefano, Magnetic iro oxide nanoparticles with tunable size and free surface obtained via a “green” approach based on laser irradiation in water, J. Mater. Chem. 21 (2011) 18665.
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128
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129
64
130
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131
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