摘要
CuPbBi_(5)S_(9) compounds have been investigated as gladite for years.However,there have been no significant studies on their physical and chemical properties.This work demonstrates that upon alloying with moderate Cu,Pb,Bi,and S using an appropriate preparation method,quaternary CuPbBi_(5)S_(9) compounds can exhibit excellent figure of merit ZT within the temperature range 298-723 K.A low average velocity,low Young’s modulus and Debye temperature,and large Grüneisen parameter,determined experimentally,indicate strong lattice anharmonicity in CuPbBi_(5)S_(9) crystals.Furthermore,density functional theory calculations(local vibration of low-frequency acoustic phonons)justify the low lattice thermal conductivity of CuPbBi_(5)S_(9) compounds.Because of the low thermal conductivity(0.514 W m^(-1)K^(-1))and a relatively high power factor(293 μW m^(-1)K^(-2)),a maximum ZT of 0.42 was achieved at 723 K for CuPbBi_(5)S_(9) prepared by mechanical alloying combined with solid-state melting.Thus,CuPbBi_(5)S_(9) materials are promising candidates for use as high-performance thermoelectric materials in the intermediate-temperature range.
基金
supported by the National Natural Science Foundation of China(Grant No.11764025).
