Optical Study of Filled Tetrahedral Compounds Li3AlN2 and Li3GaN2

Abstract

A detailed analysis of the optical properties of filled tetrahedral semiconductors Li 3 AlN 2 and Li 3 GaN 2 has been performed, using the full potential linearized augmented plane wave method within the density functional theory. The real and imaginary parts of the dielectric function e(x), the optical absorption coefficient I(x), the reflectivity R(x), and the electron energy loss function are calculated within the random phase approximation. The interband transitions responsible for the structures in the spectra are specified. Looking at optical matrix element, we note that the major peaks are dominated by transition from metal s, N 2p states to N 2p, Ga 3d states. The theoretical calculated optical properties and electron energy loss spectrum yield a static dielectric constant of 5.34 and a plasmon energy of 19.47 eV for Li 3 GaN 2 . In the Li 3 AlN 2 compound, the static dielectric constant decreases to 4.75 and yields a plasmon energy of 18.5 eV. The effect of spin-orbit coupling on the optical properties is also investigated and found to be quite small, especially in the low-energy region. In order to check the reliability of our calculations, analogous results obtained for Be 3 N 2 in the same structure [space group Ia3(206)] are included in this work.

Investigations of the Electronic Structure and Bandgap of the Next‐Generation LED‐Phosphor Sr[LiAl3N4]:Eu2+—Experiment and Calculations

“…This not only suggests covalent bonding with the N sites, but a degree of sp‐hybridization in Li and Al, as well as pd‐hybridization in Sr. Strong peaks are observed in Al:s states corresponding to α in the N:p DOS of the lower VB, implying this region is characterized by Al:s–N:p covalent bonds. This is a trend seen in other materials based on XN 4 tetrahedra . The Sr:d states dominate the lower CB, although N:p states are also present.…”

“…General features of SLA's electronic structure, such as the nature of the bonding in the XN 4 tetrahedra, are shared by other phosphor materials, which in turn do not have the same luminescence properties as SLA . These general features are clearly insufficient for efficient visible light emissions.…”

Synthesis, Structure, Solid‐State NMR Spectroscopy, and Electronic Structures of the Phosphidotrielates Li3AlP2 and Li3GaP2

“…Two years later, the corresponding gallium compound Li 3 GaP 2 was also postulated . Despite the poorly characterized structure model, quantum‐chemical calculations of Li 3 AlP 2 and Li 3 GaP 2 were performed, anticipating the model of vertex‐sharing AlP 4 tetrahedra . As for lithium phosphidotetrelates, lithium phosphidoaluminates can also be connected on a line in a Gibbs composition triangle (Finetti diagram).…”

Fast Lithium Ion Conduction in Lithium Phosphidoaluminates

“…Occupation of Li ions in octahedral sites was, however, not considered. Two further publications on Li 3 AlP 2 were based on the poor structural characterization …”