The substitution of Cu by Mn in the Cu2-xMnxSnSe3 (0 ≤ x ≤ 0.20) system is presented with an objective to optimize the thermal transport and analyse thermoelectric behaviour in the low and near room temperature regime (10–350 K). The existence of hole-like small polarons as thermally activated carriers, mediating the p-type electrical transport at high temperatures (>80 K), is experimentally validated. Temperature dependence of Seebeck coefficient and electrical transport at low temperatures reveals that the variable range hopping (VRH) mechanism is responsible for conduction for temperatures (<80 K). Mn doping resulted in the improvement of the Seebeck coefficient, attaining the highest value of 228.3 μV/K at 350 K for the x = 0.20 sample. A reduction in thermal conductivity is achieved in all the Mn-doped samples, presumably due to strong point defect scattering of high-frequency phonons. The x = 0.20 sample has the lowest thermal conductivity of 1.68 W/mK at 350 K. Even though the ZT value is observed to decrease with Mn doping, enhancement in thermoelectric quality factor is seen for the sample with x = 0.05, which is attributed to the reduction in lattice thermal conductivity.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Physical and Theoretical Chemistry
- Inorganic Chemistry
- Materials Chemistry