微晶
凝聚态物理
材料科学
磁化
德拜模型
各向异性
电子迁移率
反铁磁性
热电效应
兴奋剂
中子衍射
各向同性
杂质
热容
分析化学(期刊)
结晶学
化学
晶体结构
磁场
热力学
光学
光电子学
物理
色谱法
有机化学
量子力学
冶金
作者
Andrew F. May,Michael A. McGuire,Jie Ma,Olivier Delaire,Ashfia Huq,Radu Custelcean
摘要
Single crystals of CaZn2Sb2, EuZn2Sb2, and YbZn2Sb2 were grown from melts of nominal composition AZn5Sb5 (A=Ca,Eu,Yb) with the excess melt being removed at 1073\,K. The electrical transport properties are consistent with those previously reported for polycrystalline samples. This confirms that the $p$-type carrier concentrations ranging from 2x10^{19}cm^{-3} to ~1x10^{20}cm^{-3} are intrinsic to these materials. Also consistent with transport in polycrystalline materials, the carrier mobility is found to be lowest in CaZn2Sb2, suggesting the trends in mobility and thermoelectric efficiency within these compounds are inherent to the material systems and not due to inhomogeneity or impurities in polycrystalline samples. These results suggest CaZn2Sb2 has the strongest coupling between the doping/defects and the electronic framework. Magnetization measurements reveal an antiferromagnetic transition near 13\,K in EuZn2Sb2, and the observed magnetic anisotropy indicates the spins align parallel and anti-parallel to $c$ in the trigonal lattice. Powder neutron diffraction on polycrystalline samples of CaZn2Sb2 and YbZn2Sb2 reveals smooth lattice expansion to 1000\,K, with $c$ expanding faster than $a$. The Debye temperatures calculated from specific heat capacity data and the isotropic displacement parameters are found to correlate with the carrier mobility, with the CaZn2Sb2 displaying the largest Debye temperature and smallest mobility.
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