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

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The phase evolution, sintering behavior, and microwave dielectric properties of the Zr1-x(Li1/4Nb3/4)xTiO4 system were investigated. The phase evolution of Zr1-x(Li1/4Nb3/4)xTiO4 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 $Z^{\text{TT}}Z_{\text{TT}}$ sequence (crystallized as the Zr5Ti7O24 phase). The abnormal Raman band centered at 868–878 cm-1 in the Zr1-x(Li1/4Nb3/4)xTiO4 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)xTiO4 ceramics was lowered to 1110–1200 °C, which was much lower than that of ZrTiO4 (higher than 1400 °C). The dielectric constant ($\varepsilon_{\text{r}}$) of the Zr1-x(Li1/4Nb3/4)xTiO4 ceramic increased from 34.5 to 46.6 and the temperature coefficient of resonant frequency (TCF) shifted from $-1.2$ to +75 ppm/°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)xTiO4 was responsible for the variation in its dielectric properties.
2009-05-25