Vibrational and dielectric properties of magnesium aluminate spinel: A first-principles study

The vibrational and dielectric properties of MgAl 2O 4 are investigated within the framework of density functional perturbation theory. Results of phonon frequencies at the Brillouin zone center, static dielectric constant, and electronic dielectric constant are reported. In comparison with experimental results, we find that the generalized gradient approximation potential results in more accurate phonon frequencies than local density approximation potential does. Dielectric, refractive index, extinction coefficient and infrared reflectance spectra of MgAl 2O 4 are given, and the figures suggest that MgAl 2O 4 presents good transmission properties in the spectrum range above 1000 cm − 1 and below 300 cm − 1 . ► MgAl 2O 4 has an electronic dielectric constant smaller than the lattice component. ► GGA potential results in more accurate phonon frequencies compared to LDA potential. ► Weak reflection peaks at 321 cm − 1 and 596 cm − 1 result in narrow LO-TO bands. ► Infrared spectrum suggests good transmission above 1000 cm − 1 and below 300 cm − 1 .