Magnetic phase evolution and particle size estimation study on nanocrystalline Mg–Mn ferrites

Abstract

The nanocrystalline spinel ferrite compositions of Mg x Mn 1-x Fe 2 O 4 (x = 0.0, 0.2, 0.4 and 0.5) system have been synthesized by the chemical co-precipitation route. The structural and magnetic properties have been studied by means of X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and Mossbauer spectroscopic measurements.57 Fe Mossbauer spectra of three specimens, as prepared, annealed at 200°C and sintered at 1,100°C, of the studied compositions are recorded and analyzed to study the magnetic phase evolution. The Mossbauer spectra of as-prepared samples show a paramagnetic doublet, annealed samples exhibit simultaneous presence of a central paramagnetic doublet superimposed on two broad magnetic sextets while spectra for sintered samples show two well-resolved Zeeman split sextets corresponding to the Fe 3? ions at the tetrahedral sites and the other due to the Fe 3? ions at the octahedral sites of the spinel lattice along with presence of central doublet. The particle size estimated from the probability versus hyperfine magnetic field distribution curve is in agreement with those determine from XRD and TEM analysis, validates the method employed.

Hydrothermally Synthesized Mg-Based Spinel Nanoferrites: Phase Formation and Study on Magnetic Features and Microwave Characteristics

“…Figure 1 presents the XRD patterns for the synthesized MgFe 2 O 4 (Mg ferrite), Mg 0.9 Mn 0.1 Fe 2 O 4 (Mg-Mn ferrite), and Mg 0.9 Mn 0.1 In 0.1 Fe 1.9 O 4 (Mg-Mn-In ferrite) particles collected in the 2θ range from 20° to 80°. The significant background noise and broadening of the diffraction peaks were characteristic of crystalline metal oxide particles with nanometer dimensions [19,24]. The position (diffraction angle) and relative intensity of the diffraction peaks were compared with the standard powder X-ray diffraction data (JCPDS 17-0464) to examine the crystal structure of the ferrite particles.…”

“…Chen et al attributed the superparamagnetic properties of MgFe 2 O 4 nanoparticles to the size dependence of the magnetocrystalline anisotropy in the ferrite nanoparticles [36]. Modi et al reported that when the blocking temperature of the ferrimagnetic nanoparticles is lower than RT, the ferrite nanoparticles should exhibit a superparamagnetic nature [19]. Above the blocking temperature, the magnetocrystalline anisotropy can be overcome by thermal activation; therefore, the magnetocrystalline anisotropy constant may approach zero and the magnetization direction of nanoferrites can easily follow the direction of the external magnetic field.…”

“…Nanocrystalline Mg-based ferrite particles have been successfully synthesized previously with the combustion [14,15], micro-emulsion [16], sol-gel [17], co-precipitation [18,19], and hydrothermal synthesis methods [20,21,22]. Among those wet chemistry routes (preparation techniques), the hydrothermal method is an environmentally friendly route for the preparation of crystalline nanoparticles without subsequent high-temperature annealing processing, with better compositional homogeneity for the synthesis of multi-component functional oxide materials, and with control over particle morphology and size [22,23].…”

Construction of Mn0.5Mg0.5Fe2O4 nano particles

“…The preparation techniques control not only in the ferrite characteristics like size and shape, but also in their physical properties. Ferrites are commonly prepared by the ceramic technique that involves high-temperature solid state reactions between the constituent oxides yielding particles with large and of non-uniform size [4,5]. In this regard De-León-Prado et al report to synthesis of Mg x Mn 1−x Fe 2 O 4 (x=0 -1) nano particles via sol-gel and thermal decomposition methods [6].…”