Effect of substituting of S for O: The sulfide perovskite BaZrS 3 investigated with density functional theory

We use first-principles density functional theory calculations to investigate the ground-state structure of sulfide perovskite BaZrS3. The material has a lower band gap than its oxide analog BaZrO3. Neither are ferroelectric in the ground state at T=0 K. We also examine the IR-active phonon contributions to the dielectric constant ϵ of BaZrS3, which are then compared to those of BaZrO3. The roles of atomic size, mass, and covalency are discussed with regard to band gap and dielectric response.