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RISS 인기검색어
- 검색키워드
- 저자 : M. Siva Ram Prasad (검색결과 2 건)
- 무료
- 기관 내 무료
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Effect of Sintering Temperature on the Micro Strain and Magnetic Properties of Ni-Zn Nanoferrites
D. Venkatesh,M. Siva Ram Prasad,B. Rajesh Babu,K. V. Ramesh,K. Trinath 한국자기학회 2015 Journal of Magnetics Vol.20 No.3
In this study, nanocrystalline ferrite powders with the composition Ni0.5Zn0.5Fe₂O₄ were prepared by the autocombustion method. The obtained powders were sintered at 800℃, 900℃ and 1,000℃ for 4 h in air atmosphere. The as-prepared and the sintered powders were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and magnetization studies. An increase in the crystallite size and a slight decrease in the lattice constant with sintering temperature were observed, whereas microstrain was observed to be negative for all the samples. Two significant absorption bands in the wave number range of the 400 cm<SUP>?1</SUP> to 600 cm<SUP>?1</SUP> have been observed in the FT-IR spectra for all samples which is the distinctive feature of the spinel ferrites. The force constants were found to vary with sintering temperature, suggesting a cation redistribution and modification in the unit cell of the spinel. The M-H loops indicate smaller coercivity, which is the typical nature of the soft ferrites. The observed variation in the saturation magnetization and coercivity with sintering temperature has been attributed to the role of surface, inhomogeneous cation distribution, and increase in the crystallite size.
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M. Siva Ram Prasad,B. R. Babu,K. V. Ramesh,K. Trinath 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.7
Polycrystalline Ni–Zn–Cr ferrite nanoparticles with composition Ni0.5Zn0.5CrxFe2-xO4 (for x in the range of 0.00–0.25 insteps of 0.05) were prepared through the nitrate-citrate gel autocombustion method. The as-obtained powders were ground and annealed at 1000℃ for 4 h and characterized for spinel phase using X-ray diffraction, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). X-ray diffraction revealed the existence of single phase spinel while the TEM micrographs showed the presence of nearly spherical particles with soft agglomeration. Pelleted and toroidal samples of the same ferrite compound were sintered at 1000℃ for 4 h. The dielectric constant and the dielectric loss tangent decreased with frequency in the range of 1 kHz–13 MHz while the initial permeability remained almost constant at lower measuring frequencies and thereafter increased with frequency for all samples. The observed variations have been discussed in the light of existing understanding.
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