【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.更多还原

【Abstract】 New tantalates Ba2LnTi2Ta3O15 (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) nm,c=0.388 60(2) nm.The phase transition of Ba2YTi2Ta3O15 from ferroelectric to paraelectric occurred at 180 ℃.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 (εr) of Ba2YTi2Ta3O15 approached 107,while Ba2LaTi2Ta3O15 ceramic approached 194,combined with a low dielectric loss of 8×10-4 at 1 MHz.Ba2LaTi2Ta3O15 might be a suitable candidate of high εr microwave dielectric ceramics.更多还原