Structural, elastic, electronic and optical properties of layered alkaline-earth halofluoride scintillators

Abstract

A systematic investigation of structural properties at ambient as well as at high pressure has been carried out for layered scintillators CaClF, CaBrF, SrClF, SrBrF and SrIF based on density functional theory. Semi-empirical dispersion correction scheme has been used to account for the van der Waals interactions and the obtained results are in good agreement with experimental data. The pressure-dependent structural and elastic properties reveal that the c-axis is more compressible than the a-axis (C ) in all these materials due to weakly bonded layers stacked along the c-axis. In addition, the electronic structure and optical properties of these materials are calculated using Tran-Blaha-modified Becke-Johnson (TB-mBJ) potential. Among the five investigated compounds which are structurally anisotropic, a weak optical anisotropy is found in CaClF and SrClF and strong optical anisotropy in CaBrF, SrBrF and SrIF. The present study suggests that unlike alkaline-earth dihalides which are fast scintillators, these materials can act as storage phosphors and the possible reason is speculated from the band structure calculations.

Keywords:

• storage phosphor
• scintillator
• dispersion correction
• TB-mBJ

Acknowledgments

VK would like to acknowledge IIT-HYD for the seed grant support and NSFC awarded Research Fellowship for International Young Scientists under Grant No. 11250110051. NYK would like to thank DRDO through ACRHEM for financial support, and the CMSD, University of Hyderabad, for providing computational facilities.