Optically isotropy in scintillator host compounds M₂LaCl₅ (M=Rb, and Cs): Ab-initio study

Full potential linearized augmented plane wave method (FP-LAPW) has been used to calculate the electronic structure and optical properties of high light output scintillator host compounds M₂LaCl₅ (M=Rb, and Cs) with in the Tran Blaha modified Becke Johnson (TB-mBJ) potential. These are wide band gap materials with the band gap of 4.75, and 4.72 eV for Rb₂LaCl₅, and Cs₂LaCl₅ respectively. From the calculated optical properties of these compounds, we find these compounds to be optically isotropic, though they are structurally anisotropic, which is an important criteria for the ceramic scintillators