Analysis of Infrared Reflection Spectra of (Mg _{1− <i>x</i>} Zn _<i>x</i> )Al ₂ O ₄ Microwave Dielectric Ceramics

Abstract

Infrared reflection spectra of (Mg 1− x Zn x )Al 2 O 4 ceramics were analyzed by Kramers–Kroning analysis and classical oscillator model simulation. The dielectric properties were extrapolated down to the microwave range using the classical oscillator model for fitting the dielectric function. According to structure analysis, the losses originating from bend vibration and stretch vibration of the bond between A‐site cation and oxygen anion dominated the whole dielectric losses of the spinel ceramics. The coexistence of Mg and Zn deteriorated the intrinsic dielectric properties due to the bond asymmetry thus introduced. The calculated Qf (∼10 5 GHz) was much higher than the measured ones (∼10 4 GHz), suggesting that the extrinsic loss was significant. Therefore, the microwave dielectric properties of MgAl 2 O 4 and ZnAl 2 O 4 could be improved much by microstructure modification, and the little superiority in their solution compared with the end‐members was due to microstructure improvement.