CdGeAs_2晶体的热膨胀行为研究  

Thermal Expansion Behaviors of CdGeAs_2 Crystal

作　　者：甄珍[1] 赵北君[1] 朱世富[1] 何知宇[1] 陈宝军[1] 黄巍[1] 蒲云肖 钟义凯 

机构地区：[1]四川大学材料科学与工程学院,成都610064

出　　处：《无机材料学报》2016年第2期165-170,共6页Journal of Inorganic Materials

基　　金：国家自然科学基金重点项目(50732005);国家863计划项目(2007AA03Z443)~~

摘　　要：采用WinTA 100热膨胀仪研究了四方黄铜矿CdGeAs_2晶体在320~620 K温度范围内的热膨胀行为,探索了CdGeAs_2晶体热膨胀各向异性的物理机制。测定晶体a轴和c轴方向的热膨胀系数αa和αc发现,αa〉〉αc〉0,表现出强烈的各向异性热膨胀特性。利用最小二乘法,拟合出CdGeAs_2晶体的晶格常数（a,c）与温度（T）的函数关系式,与文献报道值吻合。分别计算出不同温度下的四方畸变因子δ=2–c/a,Cd-As键长（lCd As）和Ge-As键长（lGe As）以及相应的热膨胀系数αCd As和αGe As。结果表明,a、c、δ、lCd As、lGe As和αCd As均随着温度的升高而增大,c/a和Ge As则随着温度的升高而减小。当T=360 K时,αCd As是αGe As的6.36倍,是造成CdGeAs_2晶体强烈热膨胀各向异性的主要原因。Thermal expansion measurements by WinTA 100 on tetragonal chalcopyrite cadmium germanium arsenide （CdGeAs2） crystal were carried out in the temperature range between 320 K and 620 K. Based on these measurements, the mechanisms of thermal expansion anisotropy is proposed. It is found that the axial thermal expansion coefficients （ aa and ac） are both positive, and aa〉〉ac, which exhibits anisotropic thermal behavior intensively. By the least squares method, the functional relationship between structural parameters （a, c） and temperature （T） is set up, which are coincident with published literature. Furthermore, the tetragonal distortion 6=2-c/a, the interatomic distances （lcd-gs and lGc-As） and the bond expansion coefficients （aCd-As and aGe-As） are calculated at different temperatures, respectively. Simultaneously, it is also found that a, c, δ, lCd-As, lGe-As, and aGe-As increase with temperature increase, while c/a and aGe-As are just the opposite. When T=360 K, aCd-As is 6.36 times of aG-As. Hence, the difference between aCd-As and aGe-As is the main reason for the significant anisotropy of thermal expansion.

关 键 词：CdGeAs_2晶体 热膨胀 四方畸变 

分 类 号：O736[理学—晶体学]