Abnormal Elastic Changes for Cubic-Tetragonal Transition of Single-Crystal SrTiO_(3)  

作　　者：Caizi Zhang Fangfei Li Xinmiao Wei Mengqi Guo Yingzhan Wei Liang Li Xinyang Li Qiang Zhou 张才姿;李芳菲;魏鑫苗;郭梦琪;魏颖展;李亮;李新阳;周强(State Key Laboratory of Superhard Materials,Jilin University,Changchun 130012,China;Synergetic Extreme Condition User Facility,Jilin University,Changchun 130012,China)

机构地区：[1]State Key Laboratory of Superhard Materials,Jilin University,Changchun 130012,China [2]Synergetic Extreme Condition User Facility,Jilin University,Changchun 130012,China

出　　处：《Chinese Physics Letters》2022年第9期33-40,共8页中国物理快报（英文版）

基　　金：support from China Postdoctoral Science Foundation(Grant No.2020M670841);support from the National Key Research and Development Program of China(Grant No.2017YFA0403704);supports from the National Natural Science Foundation of China(Grant Nos.12074141,42102030,and 11974129);support from Jilin Provincial Science and Technology Development Project(Grant Nos.20210402054GH and 20210509038RQ);support from the Program for Science and Technology of Education Department of Jilin Province(Grant No.JJKH20211036KJ);the Fundamental Research Funds for the Central Universities。

摘　　要：Strontium titanate(SrTiO_(3))is a typical perovskite-type ceramic oxide and studying its high-pressure phases are critical to understand the ferroelastic phase transition.SrTiO_(3)also can be used as an important analog of davemaoite(CaSiO_(3))to understand the compositional and velocity structure of the Earth’s interior.However,the high-pressure studies on the cubic-to-tetragonal phase transition pressure and elastic properties remain unclear for SrTiO_(3).Here,we investigate the phase transition and elasticity of single-crystal SrTiO_(3)by Raman and Brillouin scattering combined with diamond anvil cell.The acoustic velocities of single-crystal SrTiO_(3)and the independent elastic constants of cubic and tetragonal SrTiO_(3)are determined up to 27.5 GPa at room temperature.This study indicates that C_(11),C_(12),and C_(44)exhibit abnormal changes at 10.3 GPa,which is related to the cubicto-tetragonal phase transition.Interestingly,a significant softening on shear modulus and a large anisotropy of shear wave splitting(A_(S)^(PO))jump are observed at 10.3 GPa.Using obtained elastic constants,the coefficients of the Landau potential are calculated to understand the phase transition between cubic and tetragonal.The calculated coefficients of the Landau potential are,λ_(2)=3.12×10^(-2)GPa,λ_(4)=-2.02×10^(-2)GPa,B~*=1.34×10^(-4)GPa and B=1.66×10^(-4)GPa.The elastic results have profound implications in understanding the structure of the Earth’s interior and indicate that the presence of tetragonal Ti-bearing CaSiO_(3)helps to explain the large APO S of the Earth’s mid-mantle.

关 键 词：SOFTENING CUBIC TETRAGONAL 

分 类 号：TQ174.1[化学工程—陶瓷工业]