Defect Engineering for Control of Polarization Properties in SrBi2Ta2O9
Defect Engineering for Control of Polarization Properties in SrBi2Ta2O9
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DOI：
10.1143/jjap.41.7062
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发表时间：
2002-11
影响因子：
1.5
通讯作者：
Y. Noguchi;M. Miyayama;K. Oikawa;T. Kamiyama;M. Osada;M. Kakihana
中科院分区：
文献类型：
--
作者：
Y. Noguchi;M. Miyayama;K. Oikawa;T. Kamiyama;M. Osada;M. Kakihana
提出了SrBi 2 Ta 2 O 9（SBT）剩余极化（Pr）和矫顽场（Ec）设计的缺陷工程。与取代基或氧化物空位耦合的阳离子空位被证明在确定极化特性中起着至关重要的作用。高分辨率中子粉末衍射研究表明，三价阳离子（Bi、La和Nd）取代会导致Sr空位，以满足电中性的要求。致密陶瓷的极化曲线表明，Bi取代导致2 Pr增加，Sr0.73Bi2.18Ta2O9的2 Pr值是SBT的2倍。结构的改进表明，Bi取代增强自发极化（Ps）和Ps的改善是负责观察到的较大的2 Pr。Sr空位的La替代使Pr略有增加，但La_（0.33）Sr_（0.5）Bi_2 Ta_2 O_9的2 Ec值（41 kV/cm）远小于SBT的2 Ec值（57 kV/cm）。Nd取代的SBT表现出几乎相同的Pr的La-SBT，而高的2 Ec（125 kV/cm）达到Nd 0.33Sr 0.5Bi2Ta2O9。有人建议，较高的Ec发现在Nd-SBT是由于氧化物空位产生的替代非常少量的Nd在Ta网站。缺陷工程有望为SBT中偏振特性的设计开辟道路。
Defect engineering to design for remanent polarization (Pr) and coercive field (Ec) in SrBi2Ta2O9 (SBT) is proposed. Cation vacancies coupled with substituents or oxide vacancies are shown to play an essential role in determining the polarization properties. High-resolution neutron powder diffraction studies revealed that trivalent-cation (Bi, La, and Nd) substitution induces Sr vacancies for the requirement of charge neutrality. Polarization measurements of dense ceramics indicated that Bi substitution led to an increase in 2Pr and the 2Pr value for Sr0.73Bi2.18Ta2O9 was twice as large as that of SBT. Structural refinements revealed that Bi substitution enhances spontaneous polarization (Ps) and the improvement of Ps is responsible for the larger 2Pr observed. La substitution with Sr vacancies increased Pr slightly, but the 2Ec value (41 kV/cm) of La0.33Sr0.5Bi2Ta2O9 was much smaller than that for SBT (57 kV/cm). Nd-substituted SBT showed almost the same Pr of La–SBT, while a high 2Ec (125 kV/cm) was attained for Nd0.33Sr0.5Bi2Ta2O9. It is suggested that the higher Ec found in Nd–SBT is attributed to oxide vacancies produced by the substitution of a very small amount of Nd at the Ta site. Defect engineering is expected to open the way for the design of the polarization properties in SBT.