Journal of Pure and Applied Ultrasonics

N. Varalaxmi ¹, M. Venkata Ramana ¹, N. Ramamanohar Reddy ¹, K. V. Sivakumar ¹, E. Rajagopal ¹, V. R. K. Murthy ²

Affiliations
1 Ceramic Composite Materials Laboratory, Department of Physics, Sri Krishnadevaraya University, Ananthapur - 505 003, IN
2 Department of Physics, Indian Institute of Technology, Chennai - 600 036, IN

Abstract

Two series of NiMgCuZn ferrites namely 1) Ni_xMg_0.6xZn_0.3Fe₂O₄ with x=0.0,0.1,0.2,0.3; 2)Ni_0.35Mg_0.2yCu_0.05Zn_0.5-yFe₂O₄ with y=0.0,0.1,0.2 were prepared by conventional double sintering process with a view to examine their use as core materials for microinductor applications. The x-ray analysis revealed the single phase formation. In order to examine their elastic behaviour, the temperature variation of longitudinal modulus and acoustic loss (Q^-1) of these samples at 142 kHz were studied in temperature range 300 to 630 K using composite resonator technique. The longitudinal modulus showed an abrupt break near curie temperature transition in all the samples studied in the present work. The temperature variation of internal friction loss (Q^-1) showed a corresponding stress induced relaxation peak at this phase transition. The results are explained in the light of structural phase transition.

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