SEMINAR 

　　Key Laboratory of Transparent Opto-functional Inorganic Materials 

　　中国科学院透明光功能无机材料重点实验室 

　　A Study of Crystal-site Structure and Solid-Solution Region of Langasite-type Oxide Crystal with Four Elements 

　　Dr. Hengyu Zhao 

　　Institute of Material Research 

　　Tohoku University 

　　时间：2015年4月23日 上午10:00 

　　地点：中试基地5号楼4楼会议室 

　　联系人：苏良碧研究员（69987734） 

　　报告摘要： 

　　Langasite-type (LGS-type) crystal with A₃BC₃D₂O₁₄ structure has been intensively studied as a group of piezoelectric crystal. The well-known langasite-type crystal with three elements, such as langasite (LGS, La₃Ga₅SiO₁₄) and langatate (LTG, La₃Ta_0.5Ga_5.5O₁₄) were found to be incongruent materials, which lead to formation of secondary phase and degradation of the quality of bulk crystals. Ca₃TaGa₃Si₂O₁₄ (CTGS), known as langasite-type crystal with four elements, has an ordered structure and is regarded as promising material in high temperature piezoelectric crystal.  

　　This presentation will introduce the crystal-site structure of CTGS, and introduce an inventive method to determine solid-solution region which is performed by electron probe micro-analysis (EPMA). This presentation will investigate the congruency or incongruency of CTGS, and try to reveal the formation mechanism of secondary phase in CTGS crystal grown by micro-pulling down (µ-PD) method. 

　　报告人简介： 

　　Dr. Hengyu Zhao got granted Ph.D in Tohoku Univ., Japan, 2015, supported by Global COE Program, JSPS, MEXT (Ministry of Education, Culture, Sports, Science and Technology), and Graduate College of Takuetsu, MEXT, Japan. His research interest is high temperature piezoelectric crystal and crystal growth science.