The features of deformation-stimulated RbI luminescence

L N Myasnikova,A G Maratova,K Sh Shunkeyev

doi:10.32523/ejpfm.2021050406

Abstract

This paper studies deformation-stimulated features of radiative relaxation of self-trapped excitons and recombination assembly of exciton-like luminescence in RbI crystal. Methods of research were luminescence and thermal activation spectroscopy. The identity of the mechanism of manifestation of the X-ray luminescence, tunnel luminescence and thermally stimulated luminescence spectra were found in the elastically deformed RbI crystal, interpreted by the luminescence of self-trapped exciton, tunnel recharge of F′, VK -pairs and thermally stimulated recombination of e−, VK -centres, respectively.The temperatures of the maximum destruction peaks of thermally stimulated luminescence, their spectral composition and activation energies were determined experimentally, on the basis of which the mechanisms of recombination assembly of exciton-like luminescences in a RbI crystal were interpreted. Uniaxial elastic deformation leads to the effective formation of point radiation defects ( F′, HA, VK -centers) in comparison with an unbroken lattice, where the predominant mechanism is the association of interstitial atoms ( H -centres) with the formation of I3−-centres.

Highlights

This paper studies deformation-stimulated features of radiative relaxation of self-trapped excitons and recombination assembly of exciton-like luminescence in RbI crystal
Uniaxial elastic deformation leads to the effective formation of point radiation defects ( F′, HA, VK centers) in comparison with an unbroken lattice, where the predominant mechanism is the association of interstitial atoms ( H -centers) with the formation of I3− -centers
It is known that three self-trapped excitons (STEs) bands were registered in the X-ray and photoluminescence spectra at a temperature of 4.2 K for RbI crystal, the maxima of which are located at 3.9 eV ( σ ) and 2.3 eV ( π ), as well as 3.1 eV ( Ex ) [1,2, 8,9,10]

Summary

Introduction

The reliably established mechanisms of the manifestation of the intrinsic luminescence of alkali halide crystals (AHCs), which is carried out through a self-trapped exciton state [1,2,3], formed due to the deformation of the crystal lattice, provides the widest opportunities for further investigation of the radiative relaxation of exciton-like structures with a decrease in the lattice symmetry [4,5,6,7].Eurasian Journal of Physics and Functional Materials, Vol.5(4). 219In AHCs, the molecular two-center structure of self-trapped excitons (STEs) is very dependent (sensitive) on the symmetrical arrangement of crystal-forming particles, and the slightest decrease in the lattice symmetry increases the probability of an unstable state of STEs ending in their decay, mainly through two channels: primary radiation defects and luminescence [8,9,10,11].Local deformations due to the difference in the sizes of both anionic and cationic homologues [2, 5], point vacancy and radiation defects [12,13], as well as uniaxial elastic deformation [6, 11, 14] have traditionally been used as reducing the symmetry of the lattice of AHCs.In the experimental plan, elastic deformation is successfully used as a method of influencing the relaxation processes of STEs, and for recognizing the nature of luminescence in AHCs [15]. The temperatures of the maximum destruction peaks of thermally stimulated luminescence, their spectral composition and activation energies were determined experimentally, on the basis of which the mechanisms of recombination assembly of exciton-like luminescences in a RbI crystal were interpreted.

Results

Conclusion