EFFECT OF PREPARATION ON MAGNETIC PROPERTIES OF Mn-Zn FERRITES (original) (raw)
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Effect of preparation on magnetic properties of Mn-Zn ferrite
Mixed ferrites belonging to the type Mn 0.9 Zn 0.1 Fe 2 O 4 have been prepared by the double sintering method and by the chemical co-precipitation for comparing their magnetic properties. Sintered and precipitated ferrites exhibit different characteristics, especially in their magnetic properties like magnetization (M s), coercive field (H c) and Curie temperature (T c). The sintered particles were size reduced in order to compare with the nanosized co-precipitated particles. The effect of grinding has also been studied. Particles have been collected at regular intervals of grinding and their properties have been studied. The increase in the coercive field has been recorded by a hysteresis curve tracer confirming size reduction. X-ray diffraction studies confirmed the structure and consequent size reduction.
Effect of sintering conditions on microstructure and magnetic properties of Mn-Zn ferrites
Journal of Materials Science, 1995
Commercial and specially-prepared Mn-Zn ferrites were characterized, in terms of magnetic performance, microstructure and local composition, by various techniques. The results show the relevance of the structure of the interfaces between grains, the importance of uniform grain size and, finally, the role of composition homogeneity throughout the sample and the atmosphere utilized. The practical relevance of these findings is also discussed.
Influence of starting powder milling on magnetic properties of Mn-Zn ferrite
Processing and Application of Ceramics, 2017
In this paper, the influence of additional sieving and milling of starting industrial Mn-Zn powders on magnetic properties was investigated. The starting powder was milled for 60 minutes, followed by sieving through 325 and 400 meshes. The starting and milled powders were used to fabricate toroid shaped samples sintered at 1200°C for 2 hours. Structural parameters of the fabricated samples were analysed by X-ray diffraction and scanning electron microscopy. Complex permeability, core loss density, and hysteresis were measured using the modified watt-meter method. The complex permeability and hysteresis loop were modelled with a new model proposed in the paper. The core loss density was modelled with the Steinmetz empirical equation. The experimental results and calculations show the significance of the additional milling and sieving process on magnetic properties of Mn-Zn ferrite in the frequency range 0.1-10 MHz. These processes increase the relative permeability about 3 times and decrease the core loss 4 times by milling of the starting powder.
Journal of Magnetism and Magnetic Materials, 2008
The effects of annealing temperature and manganese substitution on the formation, microstructure and magnetic properties of Mn x Zn 1Àx Fe 2 O 4 (with x varying from 0.3 to 0.9) through a solid-state method have been investigated. The correlation of the microstructure and the grain size with the magnetic properties of Mn-Zn ferrite powders was also reported. X-ray diffraction (XRD), a scanning electron microscope (SEM) and a vibrating sample magnetometer (VSM) were utilized in order to study the effect of variation of manganese substitution and its impact on crystal structure, crystalline size, microstructure and magnetic properties of the ferrite powders formed. The XRD analysis showed that pure single phases of Mn-Zn ferrites were obtained by increasing the annealing temperature to 1200-1300 1C. Increasing the annealing temperature to X1300 1C led to abnormal grain growth with inter-granular pores and this led to a decrease in the saturation magnetization. Moreover, an increase in the Mn 2+ ion substitution up to x ¼ 0.8 increased the lattice parameter of the formed powders due to the high ionic radii of the Mn 2+ ion. Mn-Zn ferrites phases were formed and the positions of peaks were shifted by substituting manganese. The average crystalline size was increased by increasing the annealing temperature and decreased by increasing the substitution by manganese up to 0.8. The average crystalline size was in the range 95-137.3 nm. The saturation magnetization of the Mn-Zn-substituted ferrite powders increased continuously with an increase in the Mn concentration up to 0.8 at annealing temperatures of 1200-1300 1C. Further increase of Mn substitution up to 0.9 led to a decrease of saturation magnetization. The saturation magnetization increased from 17.3 emu/g for the Mn 0.3 Zn 0.7 Fe 2 O 4 phase particles produced to 59.08 emu/g for Mn 0.8 Mn 0.2 Fe 2 O 4 particles. r
Mn-Zn ferrite powders (Mn 0.5 Zn 0.5 Fe 2 O 4 ) were prepared by the nitrate-citrate auto-combustion method and subsequently annealed in air or argon. The effects of heat treatment temperature on crystalline phases formation, microstructure and magnetic properties of Mn-Zn ferrite were investigated by X-ray diffraction, thermogravimetric and differential thermal analysis, scanning electron microscopy and vibrating sample magnetometer. Ferrites decomposed to Fe 2 O 3 and Mn 2 O 3 after annealing above 550 1C in air, and had poor magnetic properties. However, Fe 2 O 3 and Mn 2 O 3 were dissolved after ferrites annealing above 1100 1C. Moreover, the 1200 1C annealed sample showed pure ferrite phase, larger saturation magnetization (M s =48.15 emu g À 1 ) and lower coercivity (H c = 51 Oe) compared with the auto-combusted ferrite powder (M s =44.32 emu g À 1 , H c = 70 Oe). The 600 1C air annealed sample had the largest saturation magnetization (M s = 56.37 emu g À 1 ) and the lowest coercivity (H c = 32 Oe) due to the presence of pure ferrite spinel phase, its microstructure and crystalline size.
International Journal of Nanoscience, 2004
Nitrilotriacetate precursors have been used for synthesis of oxide materials. High permeability Mn – Zn ferrite with general formula Mn x Zn 1-x Fe 2 O 4 where x=0.3/0.35/0.4/0.45/0.5/0.55/0.6/0.65/0.7 were prepared using this novel method. Formation of cubic spinel structure was confirmed by XRD, which also provided information on formation of fine particle material. The magnetic properties of these materials were investigated after sintering the same at 950°C, 1150°C, 1250°C and 1350°C in nitrogen atmosphere and at 1050°C in air and were found to be interesting.
Relations Between Microstructure and Magnetic Properties of MN-ZN Ferrites for Power Applications
This report deals with the influence of the milling time of the row powders and with the influence of the co-additives CaO and Si2O on the microstructure and on the magnetic properties of the ferrite cores. Two categories of samples were obtained by varying the milling time and the additions. The samples differ in average grain size and porosity, therefore the electrical conductivity and magnetic properties are different for various samples. The sample with longest milling time (250 hours) and with additive presents the highest performances.
Magnetic properties of nanostructured MnZn ferrite
Journal of Magnetism and Magnetic Materials, 2009
Mn 0.5 Zn 0.5 Fe 2 O 4 nanoparticles (10-30 nm) have been prepared via mechanochemical processing, using a mixture of two single-phase ferrites, MnFe 2 O 4 and ZnFe 2 O 4 . SQUID measurements (field-cooled magnetization curves and hysteresis loops) were performed to follow the mechanically induced evolution of the MnFe 2 O 4 /ZnFe 2 O 4 mixture submitted to the high-energy milling process. The resulting single MnZn nanoferrite phase was characterized by SQUID (M-H curve), Faraday balance (M-T curve) and transmission electron microscopy. The magnetic characteristics of the mechanosynthesized material were compared with those of bulk Mn 0.5 Zn 0.5 Fe 2 O 4 . It was found that the saturation magnetization of nanostructured Mn 0.5 Zn 0.5 Fe 2 O 4 (87.2 emu/g) is lower than that of the bulk Mn 0.5 Zn 0.5 Fe 2 O 4 , but, the Né el temperature of the sample (583 K) is higher than that of the bulk Mn 0.5 Zn 0.5 Fe 2 O 4 .
Heat treatment effects on microstructure and magnetic properties of Mn–Zn ferrite powders
Journal of Magnetism and Magnetic Materials, 2010
Mn-Zn ferrite powders (Mn 0.5 Zn 0.5 Fe 2 O 4 ) were prepared by the nitrate-citrate auto-combustion method and subsequently annealed in air or argon. The effects of heat treatment temperature on crystalline phases formation, microstructure and magnetic properties of Mn-Zn ferrite were investigated by X-ray diffraction, thermogravimetric and differential thermal analysis, scanning electron microscopy and vibrating sample magnetometer. Ferrites decomposed to Fe 2 O 3 and Mn 2 O 3 after annealing above 550 1C in air, and had poor magnetic properties. However, Fe 2 O 3 and Mn 2 O 3 were dissolved after ferrites annealing above 1100 1C. Moreover, the 1200 1C annealed sample showed pure ferrite phase, larger saturation magnetization (M s =48.15 emu g À 1 ) and lower coercivity (H c = 51 Oe) compared with the auto-combusted ferrite powder (M s =44.32 emu g À 1 , H c = 70 Oe). The 600 1C air annealed sample had the largest saturation magnetization (M s = 56.37 emu g À 1 ) and the lowest coercivity (H c = 32 Oe) due to the presence of pure ferrite spinel phase, its microstructure and crystalline size.
Journal of Crystal Growth, 2006
The study investigates the effects of hafnia (0.2, 0.4 and 0.6 wt%) along with impurities such as 0.02 wt% SiO 2 and 0.04 wt% CaO on the microstructure and magnetic properties of Mn-Zn ferrites. The specimens have been prepared by the conventional mixed oxide method. It has been revealed that the substitution of hafnium into Mn-Zn ferrites enhances the grain growth. Measurements of initial permeability, resistivity and power loss have been related to the microstructure of sintered ferrites in particular to grain size, porosity and grain boundary phases. The present paper gives a summary that optimum properties could be achieved with additive level of 0.4 wt% HfO 2 .