Thermoelectric properties of quaternary chalcogenide Cu <sub>2</sub> ZnSnS <sub>4</sub> synthesised by mechanical alloying
Bui Duc Long, Nguyen Van Khanh, Ngoc Binh Duong, Nguyen Hong Hai
Abstract
The quaternary chalcogenide Cu2ZnSnS4 has emerged as a potential thermoelectric (TE) material due to its low thermal conductivity (κ), high Seebeck coefficient (S) and composition including earth-abundant, low-cost and non-toxic elements. In this work, Cu2ZnSnS4 was synthesised from a mixture of Cu, Zn, Sn and S powders using a mechanical alloying method. As a result, Cu2ZnSnS4 powders were formed after 16 h of milling, without additional heat treatment. After milling, the powders were heat-treated at 723 K for 24 h and then sintered by spark plasma sintering under an applied pressure of 60 MPa at 873 K for 10 min. The heat-treated Cu2ZnSnS4 sample showed a wide-band-gap of 1.49 eV. The sintered Cu2ZnSnS4 sample exhibited S and κ values of 170 μV K−1 and 1.06 W m−1 K−1, respectively with an electrical conductivity σ of 1240 S m−1 and a dimensionless figure of merit (ZT) of 0.022 at 663 K.