Configurational instability at the excited impurity ions in alkaline earth fluorites

TL;DR

This paper proposes a new mechanism for defect formation in ionic crystals involving Jahn-Teller instability near excited impurity ions, emphasizing the role of configuration interaction and impurity state localization.

Contribution

It introduces a novel defect formation mechanism linked to Jahn-Teller instability and Fano effect near excited impurity ions in alkaline earth fluorites.

Findings

Defect formation is associated with Jahn-Teller instability near impurities.

The impurity excited state localization influences defect creation.

Configuration interaction impacts defect formation processes.

Abstract

The formation of intrinsic defects by ionizing radiation in some ionic crystals in the anion sublattice is only associated with the instability of the self-trapped exciton up to now. In this paper we propose a new mechanism for the formation of the defects in the anion sublattice associated with the Janh-Teller instability occurring near the cation impurities in the excited state. The instability occurs when the degenerate excited state of the impurity ion is localized in the conduction band. We believe that the configuration interaction between the discrete impurity level and host continuum (effect Fano) plays an important role in this process.