Thermoelectric, Magnetic, and Mechanical Characteristics of Antiferromagnetic Manganese Telluride Reinforced with Graphene Nanoplates

Mechanical and thermal stability are the two challenging aspects of thermoelectric compounds and modules. Microcrack formation during material synthesis and mechanical failure under thermo-mechanical loading is commonly observed in thermoelectric materials made from brittle semiconductors. Herein, the results of graphene-nanoplates (GNPs) reinforcement on the mechanical and thermoelectric properties of MnTe compound are reported. The binary antiferromagnetic MnTe shown promising thermoelectric characteristics due to the paramagnon-hole drag above the Neel temperature. In this study, different bulk MnTe samples are synthesized with the addition of GNPs in a small quantity (0.25-1 wt%) by powder metallurgy and spark plasma sintering. The thermoelectric factors, magnetic behavior, microstructure, and mechanical properties of the samples are evaluated and analyzed. Nearly 33% improvement is observed in the fracture toughness of MnTe reinforced with 0.25 wt% GNPs compared to the pristine structure. The Neel temperature remains approximately unaffected with the GNP inclusion; however, the low-temperature ferromagnetic phase impurity is significantly suppressed. The thermal conductivity and power factor decrease almost equally by approximate to 34% at 600 K; hence, the thermoelectric figure-of-merit is not affected by GNP reinforcement in the optimized sample.

Automated summary

In this study, the addition of GNPs to MnTe compound successfully increased its fracture toughness, suppressed low-temperature ferromagnetic impurities, and had minimal impact on thermoelectric properties.