Bytizite Cu3SbSe3: Solid-State Synthesis and Thermoelectric Performance

Bytizite (Cu3SbSe3) has attracted interest as a promising thermoelectric material because of its ultralow thermal conductivity; however, there are few experimental studies. This study investigated the optimal processing conditions for the synthesis of Cu3SbSe3 using mechanical alloying (MA) and hot pressing (HP). The MA powder exhibited an orthorhombic Cu3SbSe3 phase, which remained even after HP. However, secondary phases of permingeatite (Cu3SbSe4) and berzelianite (Cu1.78Se) were also identified in the X-ray diffraction patterns. Thermal analysis revealed that the MA powder and HP compacts exhibited a large endothermic peak near 727 K, which corresponds to the melting point of Cu3SbSe3. Dense compacts with a relative density higher than 99% were obtained at HP temperatures above 573 K. Microstructural and elemental analyses confirmed the presence of the secondary phase Cu3SbSe4 in the matrix of Cu3SbSe3. However, the Cu1.78Se phase could not be observed. All specimens exhibited an electrical conductivity of (0.66-1.06) x 103 Sm-1, a Seebeck coefficient of 324-376 mu VK-1, and a power factor of 0.09-0.11 mWm(-1)K(-2) at 623 K. The thermal conductivity was lower than 0.7 Wm(-1)K(-1) in the measured temperature range, mainly due to the phonon scattering caused by the lone-pair electrons of Sb. A dip in thermal conductivity was observed at 423 K, which was possibly caused by the order-disorder transition of bytizite. The dimensionless figure of merit ZT increased with increasing temperature, and the maximum ZT was 0.16 at 623 K.

Automated summary

This study investigated the optimal processing conditions for the synthesis of Cu3SbSe3 and found that the mechanical alloying method produced powder with an orthorhombic Cu3SbSe3 phase. However, secondary phases of permingeatite (Cu3SbSe4) and berzelianite (Cu1.78Se) were also identified. The hot pressing method resulted in dense compacts with a high relative density, and the specimens exhibited good thermoelectric properties with low thermal conductivity and high figure of merit ZT.