Temperature and pressure dependence of the luminescence ofEu2+-doped fluoridecrystals BaxSr1−xF2 (x = 0, 0.3, 0.5 and 1): experiment and model

Abstract

This paper summarizes experimental evidence of anomalous luminescence inEu2+-doped fluoridecrystals BaxSr1−xF2 (x = 0, 0.3, 0.5 and 1). Luminescence, luminescence excitation spectra and luminescence kineticsobtained at ambient and high hydrostatic pressure at various temperatures are discussed.Hydrostatic pressure was shown to cause a redshift of normal emission and anomalous luminescence. The experimental data shows theexistence of temperature- and pressure-induced spectral transformationswhere the anomalous luminescence is replaced by normal emission ofEu2+ centers. We present a model that predicts a strong electron–lattice coupling of the trappedexcitons as well as the pressure effect of the spectral transformation from anomalous tonormal emission.