Structural, electronic and optical properties of ilmenite and perovskite CdSnO3 from DFT calculations
CdSnO3 ilmenite and perovskite crystals were investigated using both the local density and generalized gradient approximations, LDA and GGA, respectively, of the density functional theory (DFT). The electronic band structures, densities of states, dielectric functions, optical absorption and refl...
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Principais autores: | , , , , , |
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Formato: | article |
Idioma: | English |
Publicado em: |
IOP Publishing
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Assuntos: | |
Endereço do item: | https://repositorio.ufrn.br/handle/123456789/31289 |
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Resumo: | CdSnO3 ilmenite and perovskite crystals were investigated using both the local density and
generalized gradient approximations, LDA and GGA, respectively, of the density functional
theory (DFT). The electronic band structures, densities of states, dielectric functions, optical
absorption and reflectivity spectra related to electronic transitions were obtained, as well as the
infrared absorption spectra after computing the vibrational modes of the crystals at q = 0.
Dielectric optical permittivities and polarizabilities at ω = 0 and ∞ were also calculated. The
results show that GGA-optimized geometries are more accurate than LDA ones, and the
Kohn–Sham band structures obtained for the CdSnO3 polymorphs confirm that ilmenite has an
indirect band gap, while perovskite has a direct band gap, both being semiconductors. Effective
masses for both crystals are obtained for the first time, being highly isotropic for electrons and
anisotropic for holes. The optical properties reveal a very small degree of anisotropy of both
crystals with respect to different polarization planes of incident light. The phonon calculation at
q = 0 for perovskite CdSnO3 does not show any imaginary frequencies, in contrast to a
previous report suggesting the existence of a more stable crystal of perovskite CdSnO3 with
ferroelectric properties |
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