钇和钬掺杂对铋层状化合物的介电性的影响

Effect of yttrium and holmium doping on dielectric properties of bismuth layer-structured compounds

为了研究和改善铋层状化合物的介电性能,利用常规固相反应法制备了稀土钇和钬掺杂的钡铋三钛二铌氧十二陶瓷,并研究了其介电性能随温度变化的规律.X射线衍射结果表明,钇和钬能部分替代钙钛矿层中的铋,形成纯相固溶体陶瓷.所有样品的介电温谱显示出典型的弥散型铁电相变,并且介电常数和居里温度均随稀土掺杂量的增加而降低.结果表明,钙钛矿层中A位和B位多元素的共同占位导致局部成分的不均匀,从而引起铁电相变的弥散.钇和钬部分替代钙钛矿层中的铋,抑制了与铋关联的结构变形,从而减少了铁电极化.

To study and improve the dielectric properties of bismuth layer-structured compounds, we prepared yttrium and holmium doped Ba Bi3Ti2 Nb O12ceramics by conventional solid state reaction, and studied the dielectric properties in a wide temperature range. X-ray diffraction patterns showed that yttrium and holmium partially substitute bismuth in the perovskite layer of the crystal structure, forming pure phase solid solution. The temperature dependence of dielectric properties is typical of dispersive ferroelectric phase transition. The values of dielectric constant and Curie temperature decrease as the rare earth content increases.The results indicate that local composition inhomogeneity was induced by complex cationic occupation on both A and B sites in the perovskite layer, leading to dispersion of the ferroelectric phase transition. The partial substitution of bismuth with yttrium and holmium in the perovskite layer depresses the structure distortion correlated with Bismuth cations, resulting in the weakening of ferroelectric polarization.