Correlation between dielectric properties and vibration modes of xCaF₂–Ag(Nb,Ta)O₃ materials

详细信息    查看全文

• 作者：Lifeng Cao ; Lingxia Li ; Ping Zhang ; Haitao Wu ; Xue Wei
• 关键词：Ceramics ; Solid-state reaction ; X-ray diffraction ; Crystal structure
• 刊名：Journal of Alloys and Compounds
• 出版年：2009
• 出版时间：13 November 2009
• 年：2009
• 卷：487
• 期：1-2
• 页码：527-530
• 全文大小：533 K

文摘

Raman measurements of xCaF₂–Ag(Nb,Ta)O₃ perovskite ceramics, with x = 0, 4, 4.5, and 5 wt. % , are taken at room temperature. Raman spectra of the ceramics are analyzed through the characteristic parameters: peak position and line width of phonon modes. With the increase in CaF₂ concentration, the vibration frequency of A_1g(Ag) phonon, as well as the full-width-at-half-maximum (FWHM), decreases. The decrease in vibration frequency of A_1g(O) mode indicates that Nb–O and Ta–O bonds become weak. These suggest that the addition of CaF₂ leads to the distortion of (Nb,Ta)O₆ octahedra. In addition, the increase in the width of A_1g(O) stretch mode leads to the increase in permittivity and the decrease in dielectric loss of the ceramics. These conclude that the (Nb,Ta)O₆ octahedra play an important role on dielectric properties of xCaF₂–Ag(Nb,Ta)O₃ ceramics.