Crystal structure of mixed fluorites Ca(1-x)Sr(x)F(2) and Sr(1-x)Ba(x)F(2) and luminescence of Eu(2+) in the crystals

TL;DR

This study uses theoretical models to analyze the crystal structures of mixed fluorites and their Eu(2+) luminescence properties, providing insights into impurity behavior and electronic transitions relevant for optoelectronic applications.

Contribution

It presents a computational approach to predict structural and luminescent properties of mixed fluorites with Eu(2+), including impurity center distances and electronic level positions.

Findings

Calculated crystal structures of Ca(1-x)Sr(x)F(2) and Sr(1-x)Ba(x)F(2).

Determined Eu(2+)-F distances and impurity energy levels.

Analyzed luminescence parameters like Stokes shift and Huang-Rhys factor.

Abstract

Within the framework of the virtual crystal method implemented in the shell model and pair potential approximation the crystal structure of mixed fluorites Ca(1-x)Sr(x)F(2) and Sr(1-x)Ba(x)F(2) has been calculated. The impurity center Eu(2+) and the distance Eu(2+)-F in this crystals have been also calculated. The low level position of excited 4f65d configuration of the Eu(2+) ion has been expressed using phenomenological dependence on distance E(2+)-F. The dependences of Stokes shift and Huang-Rhys factor on concentration x have been received for yellow luminescence in Sr(1-x)Ba(x)F(2):Eu(2+). The value x, for which the eg -level of Eu(2+) ion will be in conduction band in Sr(1-x)Ba(x)F(2):Eu(2+) has been calculated.