Structural and Magnetic Properties of Zn-Doped Magnetite Nanoparticles Obtained by Wet Chemical Method

Abstract

The structural and magnetic properties of Fe (3−x) Zn x O 4 (x : 0, 0.1, 0.2, 0.5, 1) nanoparticles, prepared by wet chemical method, have been studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), Mössbauer spectroscopy, and magnetization measurements. The nanoparticles are polyhedrical-shaped with a narrow distribution in size as it was verified by SEM. By Rietveld analysis of XRD patterns, it was determined that the crystallites' sizes of Fe (3−x) Zn x O 4 in spinel structure is in the range of 30 to 50 nm. Hysteresis cycles, measured at different temperatures (300, 200, 100, 50, and 7 K), showed an increase in saturation, while temperature is diminished, as it is expected. All the samples, exhibited a high blocking temperature of ∼350 K, as it was determined by ZFC-FC measurements. This fact, reveals their strongly interacting superparamagnetic nature. Real ac susceptibility increases with temperature, while the imaginary part has a maximum, which depends on frequency, and it is related to a critical temperature, which depends on composition. A Néel-Arrhenius dependence of frequency on the critical temperature was found for all the samples. We determined a minimum of the effective anisotropy for x = 0.2.

In-situ high-pressure x-ray diffraction study of zinc ferrite nanoparticles

“…In Table 2, we have compared the results of our BM3 fit (V0 not fixed) with the literature. The average value of the bulk modulus obtained for bulk ZnFe2O4 is 180 (14) GPa, which agree within error bars with our value [K = 173(6) GPa]. The same can be seen for different values of K from the fits reported in Table 1.…”

“…Zinc ferrite nanoparticles were synthesized by the sol-gel method and magnetite nanoparticles were synthesized by the co-precipitation method. Details of synthesis as well as the crystal structure and magnetic properties at ambient pressure have been reported elsewhere [14]. The results obtained for the pressure dependence of the unit-cell volume are shown in Fig.…”

Antiphase boundaries in truncated octahedron-shaped Zn-doped magnetite nanocrystals

“…These truncated-octahedron shaped nanocrystals show similar values of saturation magnetization if compared with polyhedral, 40 but larger values if compared to spherical, Zn-doped magnetite nanoparticles. 41,42 The polyhedron morphology implies a situation of enclosed strain that is released in the case of the spherical nanoparticles with a disordered surface. This strain at the surface facets can promote the formation of internal lattice defects, such as ferromagnetically coupled APBs, which can be related to this magnetic enhancement.…”

High pressure in-situ X-ray diffraction study on Zn-doped magnetite nanoparticles

“…Zinc-doped magnetite nanoparticles with formula Fe nanometers. The details of the preparation as well as the characterization of the structural and magnetic properties at ambient pressure have been previously reported [6]. Samples of magnetite (of the same batch) and zinc ferrite (synthesized by sol-gel method [6,16]), with similar grain sizes, were earlier studied by means of X-ray diffraction (XRD) under compression [16].…”

“…Magnetite (Fe 3 O 4 ) has an inverse cubic spinel structure [4], while zinc ferrite (ZnFe 2 O 4 ), also known as Franklinite, has a normal cubic structure [5]. Solid solutions with general stoichiometry Fe (3-x) Zn x O 4 (x = 0, 0.1, 0.2, 0.5 and 1) have been investigated previously by us with emphasis on structure and magnetic properties at ambient pressure [6]. The research of spinel oxides under high presure has gained a considerable attention also due to possible pressure generated changes in physical properties and their applications [7 -9].…”