Manipulation of polar order in the "empty" tetragonal tungsten bronzes: Ba4-xSrxDy0.67â–¡1.33Nb10O30, x=0, 0.25, 0.5, 1, 2, 3
Manipulation of polar order in the "empty" tetragonal tungsten bronzes: Ba4-xSrxDy0.67â–¡1.33Nb10O30, x=0, 0.25, 0.5, 1, 2, 3
复制标题
DOI：
10.1063/1.4960712
复制
发表时间：
2016-08-15
影响因子：
4
通讯作者：
Morrison, Finlay D.
中科院分区：
文献类型：
--
作者：
Gardner, Jonathan;Morrison, Finlay D.
本文报道了一系列“空”四元钨青铜铁电体Ba_（4-x）Sr_xDy_（0.67）square_（1.33）Nb_（10）O_（30）（x = 0，0.25，0.5，1，2，3; square =空位）。随着x的增加，晶胞在ab平面和c轴上都收缩; x = 2是弛豫铁电体（RFE），具有相关的频率依赖性介电常数峰值，并且具有相似的T-m和T-f（Vogel-Fulcher冻结温度）值。这种观察是合理的不同阳离子occupancy：x = 2的显着的Sr A1-现场占领导致所观察到的RFE特性。这种FE到RFE的交叉与先前提出的TTB晶体化学框架一致，其中平均A-位点尺寸的减小和A1-位点耐受因子（t（A1））的同时增加有利于长程极性顺序和弛豫行为的不稳定。由于Sr占据A1位点而增加t（A1）的影响在本文报道的化合物中占主导地位。出版社：AIP Publishing
A series of "empty" tetragonal tungsten bronze (TTB) ferroelectrics, Ba4-xSrxDy0.67 square 1.33Nb10O30 (x = 0, 0.25, 0.5, 1, 2, 3; square = vacancy), is reported. With increasing x the unit cell contracts in both the ab plane and c-axis; x = 2 are relaxor ferroelectrics (RFE) with associated frequency dependent permittivity peaks and with similar T-m and T-f (Vogel-Fulcher freezing temperatures) values. This observation is rationalised by differing cation occupancies: for x = 2 significant Sr A1-site occupation leads to the observed RFE characteristics. This FE to RFE crossover is consistent with a previously proposed TTB crystal chemical framework where both a decrease in average A-site size and concurrent increase in A1-site tolerance factor (t(A1)) favour destabilization of long range polar order and relaxor behaviour. The effect of increasing t(A1) as a result of Sr occupancy at the A1 site is dominant in the compounds reported here. Published by AIP Publishing.