Pb[(Zn_(1/3)Nb_(2/3))_(0.91)Ti_(0.09)]O_3压电单晶的弛豫反常

AN ABNORMAL DIFFUSED FERROELECTRIC PHASE TRANSITION IN PIEZOELECTRIC Pb[(Zn_(1/3)Nb_(2/3))_(0.91)Ti_(0.09)]O_3 SINGLE CRYSTAL

对用改进的Bridgman法生长的Pb[(Zn1/3Nb2/3)0.91Ti0.09]O3(PZNT91/9)单晶用Laue衍射法和XRD衍射曲线定向,取(001)晶片研究材料的电学性能.结果表明,材料的介电性能呈现出明显的频率色散现象,随着测试频率的升高,介电常数的峰值温度出现反常,峰的位置向低温方向移动.用扫描电子显微镜和正交偏光显微镜研究了PZNT91/9单晶的电畴结构,发现规则排列的带状畴与杂乱分布的细畴并存.X射线荧光分析结果表明,在PZNT91/9单晶中存在着由成分分凝引起的组分变化.成分分凝引起的组分波动和电畴结构的复杂性导致了材料性能的不均匀性,并与材料铁电相变的弥散性特征相关.

Pb[(Zn1/3Nb2/3)0.91Ti0.09]O3(PZNT91/9) single crystals were grown by a modified Bridgman technique with an allomeric seed and PbO flux. Temperature dependence of dielectric constant for PZNT91/9 single crystal displays apparent frequency dispersion. The relationship between the peak temperature of dielectric constant (Tm) and frequency shows an abnormal character. Tm shifts to lower temperature with increasing frequency. The ferroelectric domain of the crystal presents complex configuration: regular arranged stripes and disarray thinner domains coexist. The results of XRFA demoustrate the existence of segregation during crystal growth, which will cause the fluctuation of composition. The fluctuation of composition and the complicated domain structure induces the heterogeneity of electrical properties, which are also considered correlating with the characterization of the diffused ferroelectric phase transition.