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

摘要:

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SrAl2Ge2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CaAl2Si2结构（空间群为P3-m1，晶胞参数a = b = 4.2339(1) Å，c = 7.4809(0) Å）. 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2-300 K低温下的比热（Cp）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的参考价值.

Abstract:

II, III and IV groups 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, SrAl2Ge2 single crystal was grown by aluminum flux at 1150℃ and characterized by powder X-ray methods. It is isotropic and crystallize in the CaAl2Si2-type structure through the Rietveld refinement method (space group P3-m1) with the lattice constants a=b=4.2339(1) Å, c=7.4809(0) Å. Temperature-depended resistivity on single crystals along the c-axis shows p-type semiconducting behavior. Heat capacity (Cp) was measured in 2-300 K and low temperature Cp 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.