A new family of ferroelectric tetragonal tungsten bronze phases, Ba2MTi2X3O15
A new family of ferroelectric tetragonal tungsten bronze phases, Ba2MTi2X3O15
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DOI：
10.1016/j.jeurceramsoc.2005.03.198
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发表时间：
2005
影响因子：
5.7
通讯作者：
M. Stennett;G. C. Miles;J. Sharman;I. Reaney;A. West
中科院分区：
文献类型：
--
作者：
M. Stennett;G. C. Miles;J. Sharman;I. Reaney;A. West
组成Ba2MTi2X3O15：M=La、Pr、Nd、Sm、Eu、Gd、Dy、Bi； X=Nb、Ta形成新的铁电相族。对于较大的 M 阳离子、La、Bi，材料在低于环境温度的 Tc 下表现出弛豫行为。随着 M 尺寸的减小，观察到急剧的一级铁电相变，并且 Gd 的 Tc 在~330°C 时升至最大值。这些相是四方钨青铜，具有 A 位有序 (BaM) 和非统计 B 位无序（Ti、Nb，M=La）。所有相均显示出具有双倍 c 和与[110]平行的多重周期性的弱超结构，这与弛豫铁电体（M=La，Bi）不相称，但与其余相相称。这些相表现出复杂的非化学计量，具有可变的 Ba:M 和 Ti:X 比率以及可变的氧含量。
The compositions Ba2MTi2X3O15: M=La, Pr, Nd, Sm, Eu, Gd, Dy, Bi; X=Nb, Ta form a new family of ferroelectric phases. With larger M cations, La, Bi, the materials exhibit relaxor behaviour with sub-ambient Tc. With decreasing M size, a sharp first order ferroelectric phase transition is observed and Tc rises to a maximum at ∼330°C for Gd. The phases are tetragonal tungsten bronzes with A-site order (BaM) and non-statistical B-site disorder (of Ti, Nb for M=La). All phases show a weak superstructure with doubled c and multiple periodicity parallel to [110] that is incommensurate for the relaxor ferroelectrics (M=La, Bi) but commensurate for the remainder. The phases exhibit complex non-stoichiometry with variable Ba:M and Ti:X ratios as well as variable oxygen content.