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Superparamagnetic and ferromagnetic behavior of ZnFe2O4 nanoparticles synthesized by microwave-assisted hydrothermal method

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Abstract

Zinc ferrite (ZnFe2O4) nanoparticles were successfully synthesized from Zn(NO3)2 · 6H2O and Fe(NO3)3 · 9H2O by microwave hydrothermal method at 150°C for 1 h. Cubic ZnFe2O4 with particle size below 7 nm was formed in the solution at pH ≥ 6. The crystallinity and particle size of ZnFe2O4 nanoparticles were increased after calcination. The effects of pH of the precursor solution and calcination on the particle size and crystallinity of the particles were studied. At room temperature the products show superparamagnetic and ferromagnetic properties, determined by their size. The formation mechanism of ZnFe2O4 was also discussed according to the experimental results.

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... The dependence of particle size on the magnetic behavior, i.e., ferromagnetic to super paramagnetic behavior by microwave-assisted hydrothermal synthesized ZnFe 2 O 4 is reported by Anukorn Phuruangrat et al. [13]. The micro-to nanometric scale ferromagnetism in ZnFe 2 O 4 is also reported to have mixed spinel state (Zn 1-x Fe x ) A [Fe 2-x Zn x ] B , where Zn 2? and Fe 3? cations are distributed both in the tetrahedral (A) and octahedral (B) sites [14]. ...
... It is found that the lattice parameter slightly increases linearly as the doping concentration increases. The minimum and maximum crystallite size is found to be nearly, 13 The distribution of the cations in the cubic spinel structure was carried out with the following assumption: ...
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The phase pure Ca²⁺-doped ZnFe2O4, spinel ferrite, synthesized by solvothermal method were analyzed using X-ray diffraction data. The structure factor corresponding to miller lattice planes and parameters like cell constants, anion positional parameter (O²⁻), etc., are calculated using Rietveld refinement strategy, considering cubic spinel structure. The cation distribution study reveals mixed spinel structure with both Ca²⁺ and Fe³⁺ ions occupying both tetrahedral A site and octahedral B site and Zn²⁺ occupying only at tetrahedral A site. The quantitative and visual electron bonding study reveals covalent bonding between A site ions and O²⁻ ions and ionic bonding between B site ions and O²⁻ ions for all the compositions and both are dominating for the composition Ca0.2Zn0.8Fe2O4. Also, the maximum entropy method-based electron density studies reveals that A–B interaction is maximum compared to A–A and B–B interactions and A–A interaction is the weakest one. The surface morphology using SEM shows spherical particle nature and energy dispersive X-ray analysis shows its stoichiometric compositions without any impurity elements. The magnetic properties are analyzed using vibrating sample magnetometer, which reveals the prepared sample with composition Ca0.2Zn0.8Fe2O4 show good ferromagnetic properties at room temperature. The observed saturation magnetization, remanent magnetization, coercivity and squareness ratio (Mr/Ms) for the composition Ca0.2Zn0.8Fe2O4 are 32.588 emu/g, 9.4265 emu/g, 407.98 gauss, and 28.95%, respectively. The present work reveals that Ca0.2Zn0.8Fe2O4 may be one of the best alternative low-cost and environment friendly semi-hard ferrite, useful in high-frequency device applications.
... All the investigated systems intend to display ferrimagnetic features that are mainly complemented from the substantial presence of ZnFe 2 O 4 component in the composite mixtures. The strong ferrimagnetic features of ZnFe 2 O 4 is well established from the previous investigations [69]. ...
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... The saturation magnetization was 10 emu/g when the particle size was 32 nm. Phuruangrat et al. [15] synthesized zinc ferrite nanoparticles by using microwave assisted hydrothermal method and obtained a saturation magnetization of 19.5 emu/g and coercivity of 9 Oe for 3.5 nm zinc ferrite nanoparticles. As seen, in recent years, many techniques have been developed to prepare magnetic zinc ferrite nanoparticles such as; ball milling, co-precipitation, sol-gel, thermal decomposition and hydrothermal method [16,17]. ...
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Superparamagnetic zinc ferrite nanoparticles with high magnetization were successfully synthesized by hydrothermal method at 110 ° C under different reaction times from 2 to 24 h. Elemental analysis of the nanoparticles determined by inductively coupled plasma atomic emission spectroscopy and energy dispersive X-ray spectrometer results proved that the samples are zinc ferrite. X-ray diffraction (XRD) and Fourier transmission infrared spectroscopy analysis displayed that zinc ferrite nanoparticles were single phase of cubic ferrite. The particles size, dXRD of the nanoparticles calculated from XRD patterns increased as the reaction time increased. From the images of transmission electron microscopy (TEM), the particle sizes, dTEM were also calculated and increased from 6.8 ± 2.5 to 10.6 ± 5.1 nm as the reaction time increased, which were consistent with the dXRD. Magnetic measurements revealed that the magnetization curves of the synthesized nanoparticles show superparamagnetic behavior with zero coercivity and remanence. And, the magnetization values also increased to a maximum value of 30.8 emu/g (measured at 20 kOe) as the particle size increased to ∼10 nm with the increase of reaction time. At this particle size limit, this is a considerable high value compared to the superparamagnetic zinc ferrite nanoparticles studies. Magnetization values were also extrapolated. It is seen that to a certain degree, the average particle sizes of the products and hence high maximum magnetization can be tuned by simply adjusting the parameter, reaction time by hydrothermal process.
... One of the most important ferrimagnetic materials is certain double oxides of iron and other metals, named ferrites. However, all oxide ferrites do not have ferrimagnetic properties (Phuruangrat, Maisang, Phonkhokkong, Thongtem, & Thongtem, 2017). The magnetic ferrites with different crystal structures are divided into two groups: 1) cubic and 2) hexagonal structures. ...
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