Achieving Low Thermal Conductivity with Triple Half-Heusler Composition

Half-Heusler (HH, general formula: XYZ) materials have been extensively researched for their potential in thermoelectric, superconductor, toplogical materials and other applications. The concept of double half-Heusler (DHH) was recently proposed as a potential strategy to reduce lattice thermal conductivity for better thermoelectric performance. In this talk, we will expand this idea further to triple half-Heusler (THH). THH phase was successfully synthesized by following an unconventional valence balance strategy. Even though both ternary components of THH phase are unstable with metallic transport properties, experimental results indicated a homogeneous and pure characteristic of synthesized samples with a large Seebeck coefficient. In addition, the lattice thermal conductivity is much lower than half-Heusler standards. Since a high thermal conductivity has been always a problem for HH-based thermoelectric materials, the synthesis of THH with very low lattice thermal conductivity can be a new direction for the high-performance of HH thermoelectrics. In addition, the new strategy to explore the huge compositional space for extended tunability of intermetallic compounds was demonstrated.