Cationic Clathrate of Type-III Ge172鈥?i>xPxTey (y 鈮?21.5, x 鈮?2y): Synthesis, Crystal Structure and Thermoelectric Properties
文摘
A first germanium-based cationic clathrate of type-III, Ge129.3P42.7Te21.53, was synthesized and structurally characterized (space group P42/mnm, a = 19.948(3) 脜, c = 10.440(2) 脜, Z = 1). In its crystal structure, germanium and phosphorus atoms form three types of polyhedral cages centered with Te atoms. The polyhedra share pentagonal and hexagonal faces to form a 3D framework. Despite the complexity of the crystal structure, the Ge129.3P42.7Te21.53 composition corresponds to the Zintl counting scheme with a good accuracy. Ge129.3P42.7Te21.53 demonstrates semiconducting/insulating behavior of electric resistivity, high positive Seebeck coefficient (500 渭V K鈥? at 300 K), and low thermal conductivity (<0.92 W m鈥? K鈥?) within the measured temperature range.