Raman Spectroscopy and Microwave Dielectric Properties of Zr1-x(Li1/4Nb3/4)xTiO4 Ceramics

The phase evolution, sintering behavior, and microwave dielectric properties of Zr1-x(Li1/4Nb3/4)(x)TiO4 system were investigated. The phase evolution of Zr1-x(Li1/4Nb3/4)(x)TiO4 was studied by X-ray diffraction analysis, scanning electron microscopy, and Raman spectroscopy. Raman analysis showed that the chemical substitution of (Li1/4Nb3/4) for Zr in the ZrTiO4 system enhanced the kinetics of ordering reactions to form the Z(TT)Z(TT) sequence (crystallized as the Zr5Ti7O24 phase). The abnormal Raman band centered at 868-878 cm(-1) in the Zr1-x(Li1/4Nb3/4)(x)TiO4 ceramics may indicate the short-range cation ordering of Li/Nb. Without any sintering aids, the sintering temperature of the Zr1-x(Li1/4Nb3/4)(x)TiO4 ceramics was lowered to 1110-1200 degrees C, which was much lower than that of ZrTiO4 (higher than 1400 degrees C). The dielectric constant (epsilon(r)) of the Zr1-x(Li1/4Nb3/4)(x)TiO4 ceramic increased from 34.5 to 46.6 and the temperature coefficient of resonant frequency (TCF) shifted from -1.2 to +75 ppm/degrees C as the content of (Li1/4Nb3/4) substitution increased from 0.3 to 0.5. The phase evolution of Zr1-x(Li1/4Nb3/4)(x)TiO4 was responsible for the variation in its dielectric properties (C) 2009 The Japan Society of Applied Physics