钛酸锶钡(Ba_xSr_(1-x)TiO_3)陶瓷制备及其介电性能的研究

Preparation and dielectric characterization of Ba_xSr_(1-x)TiO_3 ceramics by sol-gel technique

采用乙酸钡、乙酸锶和钛酸丁酯为原料的溶胶凝胶方法制备了BaxSr1-xTiO3(x=0.6)超细粉体,将BST超细粉体压制成型,进行烧结,得到(Ba0.6Sr0.4)TiO3陶瓷。通过热分析(DSC/TG)、X射线衍射(XRD)分析(Ba0.6Sr0.4)TiO3粉体合成过程及其相结构变化。采用扫描电子显微镜(SEM)描述(Ba0.6Sr0.4)TiO3烧结体的相结构和显微组织结构变化。阻抗分析仪测量(Ba0.6Sr0.4)TiO3陶瓷的-50～100℃介电温谱。实验结果表明BaxSr1-xTiO3粉体的相结构为立方相钙钛矿结构,其合成温度及烧结温度分别为800℃及1250℃,均低于传统工艺的相应温度。(Ba0.6Sr0.4)TiO3陶瓷在-50～100℃温度范围内,其电容率随着烧结温度升高而增大,介电损耗tgδ在-50～100℃温度范围内,随温度的增加而降低。1250℃的(Ba0.6Sr0.4)TiO3陶瓷烧结体样品存在介电峰弥散化。

Preparation and dielectric characterization of Ba_xSr_(1-x)TiO_3 (x=0.60) ceramics by sol-gel technique were studied. A differential thermal analysis/thermogravimetric system (DSC/TG) (Model NETZSCH STA449C, Germany) was used to investigate the thermal decomposition behavior of the Ba_xSr_(1-x)TiO_3 (x=0.60) gels. Powder X-ray diffraction (XRD, Model BRUKER Advanced, Bruker axs co., Germany) measurements were carried out to examine the crystallization and structural development of the Ba_xSr_(1-x)TiO_3 (x=0.60) powders. Scanning electron micrograph (SEM, Model JSM-5510LV,Japan) was used to examine crystallite size and morphology of the Ba_xSr_(1-x)TiO_3 (x=0.60) ceramics. Dielectric properties of the Ba_xSr_(1-x)TiO_3 (x=0.60) ceramics were characterized using a programmed cubical phase HP4284 LCR analyzer. The results showed that the synthetic temperature of (Ba_(0.6)Sr_(0.4))TiO_3 powders with cubical phase were 800℃, which are much lower than that by the conventional solid-state reaction method. The sintering temperature of Ba_xSr_(1-x)TiO_3 (x=0.60) ceramics fall to 1250℃, the overgrowth of the grain is constrained and the average grain size was ～0.5μm. The dielectric constant of the Ba_xSr_(1-x)TiO_3 (x=0.60) ceramics were affected by the sintering temperature.