DFT study of the electronic and optical properties of ternary alkali metal tetrafluoridobromates materials ABrF 4 (A=Na, K and Rb)

Abstract

This work deals with a theoretical investigation of structural, electronic,
and optical properties of alkali metal tetrafluoridobromates materials that
crystallize in tetragonal structure (NaBrF 4 , KBrF 4 , and RbBrF 4 ) using the
Density Functional Theory (DFT) within the pseudo-potential plane-wave
approach as implemented in Cambridge Serial Total Energy Package
(CASTEP) code. The structural parameters are in good agreement
compared to the experimental values stated in the literature. The
calculated electronic properties indicate that these ternary compounds are
wide bandgap semiconductor materials. NaBrF 4 is a semiconductor
compound with a direct band gap, whereas, KBrF 4 and RbBrF 4 are
semiconductors compounds together with an indirect band gap. The main
optical parameters are studied in detail. The large optical absorption range
in the ultraviolet (UV) region suggests that these semiconductor materials
could be helpful for specific implementations in UV optoelectronic
devices; therefore, this theoretical investigation is probable to motivate
future experimental works.