Thermal expansion and cation partitioning of MnFe2O4 (Jacobsite) from 1.6 to 1276K studied by using neutron powder diffraction (original) (raw)
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MnFe2O4 ferrite nanoparticle was synthesized via the sol–gel method, and structural, morphology and magnetic characteristics were investigated. X-ray diffraction analysis showed that the synthesized sample was in a single phase with a spinel-ferrite-like structure (space group Fd-3m). The scanning electron microscopy displayed homogenous spherical grains with an agglomeration of the particles. The chemical composition determined by energy-dispersive spectroscopy shows the absence of any impurities. To understand the role of magnetic interaction in MnFe2O4 spinel ferrites, the structural and magnetic properties of MnFe2O4 have been explored theoretically. Based on the first-principles methods via density functional theory and Monte Carlo simulations, the magnetic hysteresis cycle has been plotted. Using the generalized gradient and GGA-PBE approximation in the full-potential linearized augmented plane wave (FP-LAPW) method, the exchange coupling interactions between magnetic elements...
Journal of physics, 2018
The magnetic material of Manganese Ferrite (MnFe2O4) based on natural Iron sand have been successfully prepared by using co-precipitation method. The natural Iron sand, MnCl2.4H2O, HCl and NH4OH were used as raw materials to synthesize the MnFe2O4. The synthesis was carried out at various temperatures of 70, 100 and 130°C, respectively. The physical and the magnetic properties of the samples were analysed by using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Vibrating Sample Magnetometer (VSM). The diffraction pattern indicates that the MnFe2O4 is the dominant phase. The crystallite size tends to increase as the synthesis temperature increased while the saturation magnetization of MnFe2O4 tends to decrease.
Journal of Physics: Conference Series, 2018
The magnetic material of Manganese Ferrite (MnFe2O4) based on natural Iron sand have been successfully prepared by using co-precipitation method. The natural Iron sand, MnCl2.4H2O, HCl and NH4OH were used as raw materials to synthesize the MnFe2O4. The synthesis was carried out at various temperatures of 70, 100 and 130°C, respectively. The physical and the magnetic properties of the samples were analysed by using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Vibrating Sample Magnetometer (VSM). The diffraction pattern indicates that the MnFe2O4 is the dominant phase. The crystallite size tends to increase as the synthesis temperature increased while the saturation magnetization of MnFe2O4 tends to decrease.
Reverse microemulsion process was employed to prepare of nanocrystalline Mn 3+ substituted MnFe2xMnxO4ferrites. The structural, magnetic and dielectric properties were studied for different concentrations of Mn 3+ . The structural and microstructural properties were analyzed using X-ray diffraction technique (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy techniques. The phase identification of the materials was studied by Rietveld refined XRD patterns which reveals single phase with cubic symmetry for the samples. The lattice parameters were ranged in between 8.369 and 8.379 Å and do not show any significant change with the substitution of Mn 3+ . The average particles size was found to be around 11 ± 3 nm. Magnetization results obtained from the vibrating sample magnetometer (VSM) confirm that the substitution of Mn 3+ in MnFe2O4ferrite caused an increase in the saturation magnetization and coercivity. The dependence of Mössbauer parameters on Mn 3+ substitution has been analyzed. Magnetic behavior of the samples were also studied at field cooled (FC) and zero field cooled (ZFC) mode. The dependence of Mössbauer parameters on Mn3+ substitution was also analyzed. All the magnetic characterization shows that Mn 3+ substitution enhance the magnetic behavior of MnFe2O4ferrite nanoparticles.
Ceramics International, 2014
The effect of Mn substitution on temperature dependent magnetic properties of Mn substituted cobalt ferrite, i.e., Co 1−x Mn x Fe 2 O 4 (x ¼0.0-0.4), prepared by a ceramic method has been investigated. X-ray diffraction (XRD) analysis reveals that all samples posses a single phase cubic spinel structure. The lattice constant determined from XRD increases with Mn substitution whereas the bulk density of the samples decreases. Mössbauer results reveal that Co, Fe and Mn ions are distributed over the tetrahedral (A) and octahedral (B) sites for the prepared samples. Hysteresis loops yield a saturation magnetization (M s ) and coercive field (H c ) that vary significantly with temperature and Mn content (x). The temperature dependence of the magnetization obtained for μ o H¼ 5 T presents a maximum at 175 K which is also dependent on the value of x. The high field regimes of the hysteresis loops are modeled using the Law of Approach to Saturation (LAS) to determine the first-order cubic anisotropy coefficient (K 1 ). It has been found that the anisotropy of these materials increases significantly with decreasing temperature. However, below 175 K, the shape of the anisotropy energy function changes significantly causing a first-order magnetization process (FOMP) at higher fields, which also prevents the magnetization to saturate even under a maximum applied field of 5 T. In general, the anisotropy coefficient decreases with increasing Mn substitution at a given temperature, which could be explained in terms of the site occupancy of the Mn 2+ substituent in the cubic spinel lattice.
MnFe 2 O 4 nanoparticles have been synthesized with a sol-gel method. Both differential thermal and thermo-gravimetric analyses indicate that MnFe 2 O 4 nanoparticles form at 400 1C. Samples treated at 450 and 500 1C exhibit superparamagnetism at room temperature as implied from vibrating sample magnetometry. Mössbauer results indicate that as Mn 2 + ions enter into the octahedral sites, Fe 3 + ions transfer from octahedral to tetrahedral sites. When the calcination temperature increases from 450 to 700 1C, the occupation ratio of Fe 3 + ions at the octahedral sites decreases from 43% to 39%. Susceptibility measurements versus magnetic field are reported for various temperatures (from 450 to 700 1C) and interpreted within the Stoner-Wohlfarth model. Crown
Journal of Magnetism and Magnetic Materials, 2010
MnFe 2 O 4 nanoparticles have been synthesized with a sol-gel method. Both differential thermal and thermo-gravimetric analyses indicate that MnFe 2 O 4 nanoparticles form at 400 1C. Samples treated at 450 and 500 1C exhibit superparamagnetism at room temperature as implied from vibrating sample magnetometry. Mössbauer results indicate that as Mn 2 + ions enter into the octahedral sites, Fe 3 + ions transfer from octahedral to tetrahedral sites. When the calcination temperature increases from 450 to 700 1C, the occupation ratio of Fe 3 + ions at the octahedral sites decreases from 43% to 39%. Susceptibility measurements versus magnetic field are reported for various temperatures (from 450 to 700 1C) and interpreted within the Stoner-Wohlfarth model. Crown
Journal of Applied Physics, 2013
Manganese substituted cobalt ferrite, Co 1Àx Mn x Fe 2 O 4 (x ¼ 0.0-0.4), was prepared by a ceramic method. The heat-treated powders were pressed at hydrostatic pressure of 167 MPa, and were annealed at 1350 C for 24 h. These samples present a single-phase cubic spinel structure and the compositional mass ratios are close to the empirical formula. The lattice constant determined from XRD increases with the increase of Mn content, whereas SEM study reveals that Mn substitution changes the microstructure and cause pores within the grains, which reduces the bulk density of the samples. The magnetocrystalline anisotropy constant, coercive field, and magnetostriction were observed to decrease with increasing Mn substitution; however, the strain derivative (dk/dH) reaches a maximum value for x ¼ 0.3. The observed variation in strain derivative in the Mn substituted cobalt ferrite is correlated to the microstructure whereas the reduced anisotropy of the system plays only a minor role. V C 2013 AIP Publishing LLC [http://dx.
Influence of temperature on structural and magnetic properties of Co0⋅5Mn0⋅5Fe2O4 ferrites
Co 0⋅5 Mn 0⋅5 Fe 2 O 4 ferrites have been synthesized using a single-step sol-gel auto-combustion method in which the metal nitrate (MN)-to-citric acid (CA) ratio was adjusted to 0⋅5 : 1 and pH to 7, respectively. The structural and magnetic properties of as-burnt and annealed samples were studied as a function of temperature. The inverse spinel structure was confirmed by X-ray diffraction (XRD) and crystallite size was estimated by the most intense peak (311) using Scherrer's formula. Contrary to earlier studies reported in the literature, both as-burnt and annealed samples exhibit crystalline behaviour. Room temperature magnetic properties were studied using vibrating sample magnetometer (VSM) with field strengths up to ± 10 kOe. Lattice constant and crystallite size increased as the annealing temperature was increased. However, the coercivity (H c ) initially increased and then decreased with the increase of crystallite size. The variation in coercivity is ascribed to the transition from a multi-domain to a single-domain configuration. Figure 6. Variation of coercivity with annealing temperature.