Abstract
Structural and electrical transport properties of half-Heusler solid solutions have been investigated using x-ray diffraction, Mössbauer spectroscopy, resistivity, and thermopower measurements. The electronic structure of the compounds was studied using the Korringa-Kohn-Rostoker coherent potential approximation (KKR-CPA). The resistivity curves measured over the 80–800 K temperature range show a remarkable modification of versus x in i.e., a metalliclike character both in Fe-rich and Ni-rich samples and a semiconductinglike behavior near Moreover, the room-temperature Seebeck coefficient S changes from highly positive in to highly negative in while S is near zero in the and compositions. Based on the KKR-CPA results, the electrical transport properties of arise from the appearance of an energy gap at the Fermi level for the content. This electronic structure feature indicates that FeTiSb and NiTiSb can be seen as one-hole and one-electron compounds, respectively, explaining a change in sign of the Seebeck coefficient in disordered phases near
- Received 9 April 2001
DOI:https://doi.org/10.1103/PhysRevB.64.155103
©2001 American Physical Society