Thermal Stability and Thermoelectric Properties of NaZnSb

Materials

Bryan Owens-Baird¹  JuliaV. Zaikina¹  Volodymyr Gvozdetskyi¹  Sangki Hong¹ 

[1] Department of Chemistry, Iowa State University, Ames, IA 50011, USA;

关键词: antimonide;    thermoelectric;    alkali metal;    hydride;    zinc;    crystal structure;    Zintl;   

DOI  :  10.3390/ma12010048

来源: DOAJ

【 摘 要 】

A layered Zintl antimonide NaZnSb (PbClF or Cu2Sb structure type; P4/nmm) was synthesized using the reactive sodium hydride NaH precursor. This method provides comprehensive compositional control and facilitates the fast preparation of high-purity samples in large quantities. NaZnSb is highly reactive to humidity/air and hydrolyzes to NaOH, ZnO, and Sb in aerobic conditions. On the other hand, NaZnSb is thermally stable up to 873 K in vacuum, as no structural changes were observed from high-temperature synchrotron powder X-ray diffraction data in the 300–873 K temperature range. The unit cell expansion upon heating is isotropic; however, interatomic distance elongation is not isotropic, consistent with the layered structure. Low- and high-temperature thermoelectric properties were measured on pellets densified by spark plasma sintering. The resistivity of NaZnSb ranges from 11 mΩ∙cm to 31 mΩ∙cm within the 2–676 K range, consistent with heavily doped semiconductor behavior, with a narrow band gap of 0.23 eV. NaZnSb has a large positive Seebeck coefficient (244 μV∙K−1 at 476 K), leading to the maximum of zT of 0.23 at 675 K. The measured thermoelectric properties are in good agreement with those predicted by theoretical calculations.

【 授权许可】

Unknown