新铌酸盐Ba_5LnZnNb_9O_(30)(Ln=Y,La)的合成、结构与介电性能  

Synthesis,Structure and Dielectric Properties of New Niobates Ba_5LnZnNb_9O_(30)(Ln=Y,La)

作　　者：方亮[1] 杨俊峰[1] 黄涛华[1] 张辉[1] 刘韩星[1] 袁润章[1] 

机构地区：[1]武汉理工大学材料复合新技术国家重点实验室,武汉430070

出　　处：《高等学校化学学报》2004年第5期806-809,共4页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金(批准号 :5 0 0 0 2 0 0 7);教育部重大项目(批准号 :0 2 0 1);国际衍射数据中心(ICDD)Grant-in-Aid基金(批准号:0 2 -0 5 6;0 2 -0 3 7)资助

摘　　要：在 Ba O-Ln2 O3-Zn O-Nb2 O5( Ln=Y,La)体系中通过固相反应法合成了填满型钨青铜结构的新铌酸盐Ba5YZn Nb9O30 与 Ba5La Zn Nb9O30 .采用 X射线衍射分析和扫描电镜进行了结构分析 ,并进行了介电性能测试 .结果表明 ,Ba5YZn Nb9O30 为弛豫性铁电体 ,1 0 k Hz时的居里温度为 2 5℃ ;室温时为四方钨青铜结构铁电相 ,晶胞参数 a=1 .2 5 2 5 5 ( 4) nm,c=0 .3 95 3 0 ( 2 ) nm;1 MHz时陶瓷体的室温相对介电常数为 45 6.Ba5La Zn Nb9O30 在室温下为四方钨青铜结构顺电相 ,晶胞参数 a=1 .2 5 73 1 ( 3 ) nm,c=0 .3 981 2 ( 2 ) nm ;频率为 1 MHz时 ,其陶瓷的室温相对介电常数为 3 1Two new niobates Ba 5YZnNb 9O 30 and Ba 5LaZnNb 9O 30 were synthesized by high temperature solid-state reaction in the BaO-Ln 2O 3-ZnO-Nb 2O 5 system. The crystal structure and dielectric properties were characterized by using X-ray powder diffraction, scanning electron microscope and dielectric measurements. The results show that Ba 5YZnNb 9O 30 belongs to ferroelectric phase of fully filled tetragonal tungsten bronze structure at room temperature with unit cell parameters: a=1.252 55(4) nm, c=0.395 30(2) nm. Ba 5YZnNb 9O 30 has significant relaxor behavior, and the phase transition from ferroelectric to paraelectric occurred at 25 ℃ as frequency was at 10 kHz. The room temperature dielectric constant(ε r) of Ba 5YZnNb 9O 30 ceramic reached 456 at 1 MHz. While Ba 5LaZnNb 9O 30 belongs to paraelectric phase of fully filled tetragonal tungsten bronze structure at room temperature with unit cell parameters: a=1.257 31(3) nm, c=0.398 12(2) nm. The room temperature dielectric constant(ε r) of Ba 5LaZnNb 9O 30 ceramic reached 316 combined with a low dielectric loss of 0.017 at 1 MHz.

关 键 词：铌酸盐 合成 结构 介电性能 填满型钨青铜结构 弛豫性铁电体 高温固相反应法 

分 类 号：TM225[一般工业技术—材料科学与工程]