The synthesis and properties of point defect structure of Cu2-XZnSnS4 (x=0.1, 0.2, and 0.3)

Cu-based sulfides have recently emerged as promising thermoelectric (TE) materials due to their low cost, non-toxicity, and abundance. In this research, point defect structure of Cu2-xZnSnS4 (x=0.1, 0.2, 0.3) samples were synthesized by the mechanical alloying method. Mixed powders of Cu, Zn, Sn and S were milled using high energy ball milling at a rotation speed of 300 rpm in Ar atmosphere. The milled Cu2-xZnSnS4 powders were heat-treated at 723 K for 24 h, and subsequently consolidated using spark plasma sintering (SPS) under an applied pressure of 60 MPa for 15 min. The thermal conductivity of the sintered Cu2-xZnSnS4 samples was evaluated. A well-defined Cu2-xZnSnS4 powders were successfully formed after milling for 16 h, with the particle sizes mostly distributed in the range of 60-100 nm. The lattice constants of a and c decreased with increasing composition value x. The thermal conductivity of sintered x=0.1 sample exhibited the lowest value and attained 0.93 W/m K at 673 K.