Theoretical study of both low- and high-temperature $$\gamma $$-$${\text {Bi}}_{2}{\text {MoO}}_{6}$$ crystalline phases

Abstract

In order to understand the electronic properties that $$\gamma $$ (L)- $${\text {Bi}}_{2}{\text {MoO}}_{6}$$ and $$\gamma $$ (H)- $${\text {Bi}}_{2}{\text {MoO}}_{6}$$ crystalline phases present, theoretical calculations were performed under the density functional theory (DFT) method. The computed PDOS for both phases shows that although these present a difference in bandgap values (larger for $$\gamma $$ (H)- $${\text {Bi}}_{2}{\text {MoO}}_{6}$$ phase), the same type of orbitals is found at the HOMO and LUMO levels. The Lowdin charge values obtained from a population analysis suggest that the $$\gamma $$ (H)- $${\text {Bi}}_{2}{\text {MoO}}_{6}$$ phase presents a larger number of both acid and basic sites at the free surface. We also observe that the occupation degree of the valence orbitals in this phase is greater than that in the $$\gamma $$ (L)- $${\text {Bi}}_{2}{\text {MoO}}_{6}$$ phase.