ReSiAl and its related compounds are potential thermoelectric materials. Previously, it was reported to adopt a MoSi<sub>2</sub>-type structure with Si and Al atoms statistically sharing the same crystallographic sites. Our recent study indicates otherwise – Si and Al are segregated and occupy different sites. To confirm and rationalize the segregation between Si and Al, we studied this compound with first-principle calculations. Several model structures have been constructed for ReSiAl including a number of different super-cell models. Energy analysis confirmed that the model with Si/Al segregation has the lowest energy. The chemical bonding in ReSiAl was investigated by computing and comparing the band structures of the models. It was found that low energy models typically possess a bandgap. The valence electron density maps were calculated to investigate the origin of the bandgaps. Meanwhile, it was also found that bonding is not the only factor lowering the total energy. The “stacking effect” (Madelung energy) also plays an important role. These theoretical computations should provide more insight into the nature of ReSiAl and its related compounds.

Electronic and structural <i>ab init</i>io calculations of ReSiAl models

2019 Spring National Meeting

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Electronic and structural ab initio calculations of ReSiAl models