层状热电材料SrAl2Ge2的制备与性质研究

Investigation on the preparation and thermoelectric properties of layered SrAl2Ge2

以Ⅱ、Ⅲ和Ⅳ族元素为主的笼状物热电材料研究近年来发展迅速,尤其是在优值系数ZT值上取得了重大突破,而从Sr-Al-Ge笼状物体系中获得的层状结构热电材料却鲜有人关注.本研究利用铝元素作为助溶剂,在1150℃下成功合成了层状SrAl_2Ge_2单晶.采用X射线衍射仪对样品粉末进行表征,通过Rietveld精修证明该晶体具有CaAl_2Si_2结构(空间群为P3-m1,晶胞参数a=b=4.2339(1)?,c=7.4809(0)?).变温电阻率测试发现单晶样品沿c轴方向具有p型半导体行为,此外其在2~300K低温下的比热(C_p)数据符合德拜模型.本研究结果对于开发新型无毒、高性能热电材料具有一定参考价值.

Ⅱ,ⅢandⅣgroups were widely investigated to synthesize guest-host thermoelectric compounds in order to obtain high optimal ZT value materials.While a novel layered structure was less reported for Sr-Al-Ge system.In this study,SrAl 2 Ge 2 single crystal was grown by aluminum flux at 1150℃and characterized by powder X-ray methods.It is isotropic and crystallize in the CaAl 2 Si 2-type structure through the Rietveld refinement method(space group P3-m1)with the lattice constants a=b=4.2339(1),c=7.4809(0).Temperature-depended resistivity on single crystals along the c-axis shows p-type semiconducting behavior.Heat capacity(C p)was measured in 2~300 K and low temperature C p was consistent with data calculated by using Debye model.This work opens up a novel avenue for seeking and designing environment-friendly and high-performance thermoelectric materials.