Structural, mechanical, electronic, and thermoelectric properties of TiZrCo2Bi2, TiHfCo2Bi2, and ZrHfCo2Bi2 double half Heusler semiconductors

The structural, mechanical, electronic, and thermoelectric properties of the new double half Heusler alloys (DHHs) TiZrCo2Bi2, TiHfCo2Bi2, and ZrHfCo2Bi2 are investigated by the full potential linearized augmented plane waves (FP-LAPW) method within the density functional theory. The generalized gradient approximation (GGA) is used to define the exchange–correlation potential. Their ground states parameters such lattice constants, bulk modulus, and its pressure derivative are computed. In addition, the elastic constants, bulk, shear, and Young’s moduli are calculated, denoted the mechanical stability of these systems, and their classification as brittle and anisotropic materials with ionic bonding. The band’s structure depicts a semiconductor behavior with indirect band gaps in the range of 0.906 to 1.005 eV. The dos diagrams display that the valence and the conduction bands are dominate by d states of Ti, Co, Zr, and Hf atoms. From the thermoelectric investigation, it is inferred that these DHHS are p-type materials and are candidates for thermoelectric devices.