Structural investigation of the SrAl2O4-BaAl2O4 solid solution system with unstable domain walls
Structural investigation of the SrAl2O4-BaAl2O4 solid solution system with unstable domain walls
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DOI：
10.1016/j.jssc.2017.03.002
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发表时间：
2017-05-01
影响因子：
3.3
通讯作者：
Mori, S.
中科院分区：
文献类型：
--
作者：
Ishii, Y.;Tsukasaki, H.;Mori, S.
利用原位粉末X射线衍射和透射电子显微镜研究了Ba_（1-x）Sr_xAl_2 O_4（x ≥ 0.6）固溶体系统的结构相变。结构相变P6（3）22 P6（3）（根3a（p））P2（1）的序列发生在x=0.8-1.0的组成窗口中。Ba取代抑制了P63中间相和低温P2（1）相，它们分别在x=0.7和0.6时消失。P2（1）相界具有一阶特征，在该相界处，晶胞参数随温度升高而不连续变化，晶胞体积略有收缩。在P2（1）相中，观察到不稳定的孪晶壁;随着温度的升高，每个孪晶畴的形状和晶轴发生变化。这种不稳定性可以归因于BaAl 2 O 4和SrAl 2 O 4化合物都具有的潜在不稳定性。
We investigated the structural phase transition of the Ba1-xSrxAl2O4 solid-solution system (x >= 0.6) via in situ powder X-ray diffraction and transmission electron microscopy. The sequence of structural phase transitions P6(3)22 P6(3)(root 3a(p)) P2(1) occurs in a composition window of x=0.8-1.0. Ba substitution suppresses the P63 intermediate and low-temperature P2(1) phases, which disappear at x=0.7 and 0.6, respectively. The P2(1) phase boundary exhibits first-order characteristics, at which the cell parameters change discontinuously and the cell volume slightly contracts as the temperature increases. In the P2(1) phase, unstable twin walls are observed; the shapes and the crystal axes of each twin domain change as the temperature increases. This instability can be attributed to the latent instabilities that both the BaAl2O4 and SrAl2O4 compounds possess.