Heat treatment effects on spinel phase of Zn x Ni1 − x Fe2O4 and MnFe2O4 nanoferrites

Abstract

We report the effects of heat treatment on Zn x Ni 1−x Fe 2 O 4 (x = 0, 0.5 and 1.0) and MnFe 2 O 4 ferrite nanoparticles. The as-prepared compounds were sintered from 400 • C to 1100 • C. Pure ZnFe 2 O 4 (x = 1.0) and MnFe 2 O 4 could be obtained under low reaction temperature of 200 • C. NiFe 2 O 4 (x = 0) and Zn 0.5 Ni 0.5 Fe 2 O 4 (x = 0.5) nanoferrites crystallized with single phase cubic spinel structure after annealing at 600 • C. The single phase cubic spinel structure of these compounds was destroyed after annealing at temperature above 700 • C. The magnetization measurements indicate superparamagnetic behavior of the nanosized compounds produced.Keywords Spinel · Mössbauer spectroscopy · Nanoparticles Magnetic nanoparticles of spinel ferrites have wide applications in modern technologies such as drug delivery systems, medical diagnostics, magnetic resonance imaging contrast agents and magnetocarolic refrigeration [1, 2]. Superparamagnetism is a unique property of these nanoparticles and can be controlled by particle size. In the superparamagnetic state each nanoparticle has well defined magnetic order and behaves like a paramagnetic atom. The collective behavior of a system of magnetic nanoparticles is the same as that of a paramagnetic atom. Efforts are still being made to improve or develop synthesis techniques of magnetic nanoparticles. The magnetic properties of Zn-Ni ferrits have been studied previously [4][5][6]. Of interest are the effects of reaction temperature and sintering temperatures on single phase formation. In the present work, a wet chemical method known as glycolthermal method [3] has been used to produce Zn x Ni 1−x Fe 2 O 4 (x = 0, 0.5 and 1.0) and MnFe 2 O 4 nanoferrites.

Enhancing the electro catalytic activity of manganese ferrite through cerium substitution for oxygen evolution in KOH solutions

“…ABO 3 ) on the materials. 16,17 Most importantly, the secondary phase exists at concentration >0.4. Although the density of these grain boundaries is reduced upon treating the powders at high temperature, secondary phase are still present in the catalyst layer at high concentrations of cerium; which may hinder the mobility of charge carriers and increases the electrical resistivity.…”

“…Due to the bimetallic nature of spinels, the conductivity of ferrites can be tuned by substituting with a foreign metal, using different preparation conditions or using heat treatment. [16][17][18] Previous studies of MnFe 2 O 4 employed several synthesis methods, mostly to examine structural, electrical conductivity, magnetization and OER properties. 19,20 Recently, Shouheng Sun and his co-works found that similar ferrite system exhibits the ORR activity in alkaline solution, comparable to that of Pt.…”

Tuning Physical Properties of NiFe2O4 and NiFe2O4@SiO2 Nanoferrites by Thermal Treatment

“…For 57 Fe Mo¨ssbauer spectrometry, the τ m value is in order of 10 −8 s. It is also worth mentioning that, as previously reported for spinel nanoferrites, the Mo¨ssbauer spectra strictly depend on the chosen synthesis type and further sample processing. [5,16,17,22,24,25,34,35] In the paper of Hoque et al, [16] the influence of annealing on various physical properties, including the crystallites size of NiFe 2 O 4, is reported. Thus, the approach used by the authors reveals the emergence of a doublet line related to the processing of samples from its as-dried form to annealed up to 400 °C corresponding to the crystallites size from 2 to 4 nm.…”

Multi‐Method Characterization of the High‐Entropy Spinel Oxide Mn0.2Co0.2Ni0.2Cu0.2Zn0.2Fe2O4: Entropy Evidence, Microstructure, and Magnetic Properties

“…Due to the fact that in this system the equal atomic percentages only refer to the used divalent metals, evidences of entropy stabilization are provided in the present work. Since it is known that manganese‐containing ferrites decompose at certain temperatures, this is a useful property to demonstrate whether an entropy stabilized spinel was obtained, since a multiphase state can be obtained that can be used to verify the first two requirements (see below) [29–31] . To gain a deeper insight and understanding of the compounds, we investigated the homogeneity at the nanoscale by TEM and determined the oxidation states and the distribution of cations on the octahedral and tetrahedral sites using X‐Ray Absorption Spectroscopy (XAS) and Mössbauer spectroscopy.…”