CaF_(2)纳米晶粒结构相变行为的尺寸依赖性  

Size-Dependent Structural Phase Transition Behaviors of CaF_(2) Nanocrystals

作　　者：巩蕾 王婧姝[1] 张俊凯 陈广博 张晗[1] 武晓鑫 胡廷静[1] 崔航[2] GONG Lei;WANG Jingshu;ZHANG Junkai;CHEN Guangbo;ZHANG Han;WU Xiaoxin;HU Tingjing;CUI Hang(Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education,National Demonstration Center for Experimental Physics Education,Jilin Normal University,Siping 136000,Jilin,China;State Key Laboratory of Superhard Materials,Jilin University,Changchun 130012,Jilin,China)

机构地区：[1]吉林师范大学国家物理实验教育示范中心,教育部功能材料物理与化学重点实验室,吉林四平136000 [2]吉林大学超硬材料国家重点实验室,吉林长春130012

出　　处：《高压物理学报》2022年第2期9-16,共8页Chinese Journal of High Pressure Physics

基　　金：National Natural Science Foundation of China(11904128);Thirteenth Five-Year Program for Science and Technology of Education Department of Jilin Province(JJKH20200410KJ);Academic Graduate Students Scientific Research Innovation Fund of Jilin Normal University(202005)。

摘　　要：利用原位高压同步辐射X射线衍射方法,对尺寸为11 nm的CaF_(2)纳米晶粒进行高压结构相变和压缩特性研究。当压力为12 GPa时,观察到由萤石结构向α-PbCl_(2)结构转变的一次相变,该相变压力点远高于体材料,但略低于粒径更小的CaF_(2)纳米晶体。相比体材料,纳米尺寸的CaF_(2)样品的体弹模量更大,说明其更难被压缩。当压力释放至常压时,11 nm的CaF_(2)纳米晶粒的α-PbCl_(2)型亚稳相结构被保留下来,相变不可逆。分析了影响11 nm CaF_(2)纳米晶粒独特高压行为的原因,判定尺寸效应为主要因素,该尺寸下较高的表面能导致结构稳定性增强和体积模量增加。CaF_(2) nanocrystals with a size of 11 nm have been investigated using X-ray diffraction technique under high pressure.A phase transition from the fluorite structure to theα-PbCl_(2)-type structure has been observed at 12 GPa,which is much higher than the value observed in the bulk CaF_(2) and slightly lower than the one in smaller-sized CaF_(2) nanocrystals.The compressibility of the CaF_(2) nanocrystals is discussed,an obviously higher incompressibility than the bulk CaF_(2) is observed.Theα-PbCl_(2)-type metastable phase is retained when the pressure is released to ambient conditions.The unique high-pressure behaviors of the 11 nm-sized CaF_(2) nanocrystals are attributed to defects and grain size effect.The grain size effect is considered to be the main factor influencing the high-pressure behaviors of the CaF_(2) nanocrystals.When the size of the CaF_(2) nanocrystals is as small as 11 nm,the higher surface energy leads to the enhancement of the structural stability and the increase of the bulk modulus.

关 键 词：高压 氟化钙纳米晶粒 相变 X射线衍射 尺寸效应 

分 类 号：O521.2[理学—高压高温物理] O469[理学—物理]