新钽酸盐Ba_2LnTi_2Ta_3O_(15)(Ln=Y、La)的结构与介电性能  

Structure and Dielectric Properties of New Tantalates Ba_2LnTi_2Ta_3O_(15)(Ln=Y,La)

作　　者：方亮[1] 张辉[1] 鄢俊兵[1] 杨卫明[1] 

机构地区：[1]武汉理工大学

出　　处：《物理化学学报》2003年第1期82-84,共3页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(50002007);教育部重大项目;材料复合新技术国家重点实验室开放基金资助项目~

摘　　要：通过固相反应法合成了四方钨青铜结构新钽酸盐Ba2LaTi2Ta3O15与Ba2YTi2Ta3O15,分别进行了X射线衍射分析与介电性能测试.结果表明,Ba2LaTi2Ta3O15室温时晶胞参数为a=1.24264(5)nm,c=0.39157(2)nm,为四方钨青铜结构顺电相;Ba2YTi2Ta3O15室温时晶胞参数为a=1.23646(4)nm,c=0.38860(2)nm,为四方钨青铜结构铁电相,铁电相与顺电相转变温度为180℃.频率为1MHz时,Ba2LaTi2Ta3O15陶瓷的室温相对介电常数为194,介电损耗也降低至8×10-4.Ba2YTi2Ta3O15陶瓷的室温相对介电常数为107.New tantalates Ba(2)LnTi(2)Ta(3)O(15) (Ln = Y, La) were synthesized by Ln partial substitution for Ba in the crystal structure of Ba3TiTa4O15. The crystal structure and dielectric properties were determined by X-ray powder diffraction and dielectric measurements. The results show that Ba2YTi2Ta3O15 belongs to ferroelectric phase of tetragonal tungsten bronze structure at room temperature with unit cell parameters: a = 1.236 46 (4) run, c 0.38860 (2) nm. The phase transition of Ba2YTi2Ta3O15 from ferroelectric to paraelectric occurred at 180 degreesC. Ba2LaTi2Ta3O15 belongs to paraelectric phase of tetragonal tungsten bronze structure at room temperature with unit cell parameters: a = 1.242 64 (5) nm, c = 0.391 57 (2) nm. At room temperature, the dielectric constant (epsilon(r)) of Ba2YTi2Ta3O15 approached 107, while Ba2LaTi2Ta3O15 ceramic approached 194, combined with a low dielectric loss of 8 X 10(-4) at 1 MHz. Ba2LaTi2Ta3O15 might be a suitable candidate of high epsilon(r) microwave dielectric ceramics.

关 键 词：钽酸盐 钨青铜结构 X射线衍射 介电性能 Ba2YTi2Ta3O15 铁电体 Ba2LaTi2Ta3O15 

分 类 号：TQ174[化学工程—陶瓷工业]