Radiation-induced self-structuring of radiative defects complexes in a K-feldspar crystal: A study by thermoluminescence

Abstract

Ultraviolet light emission at a wavelength of ∼ 290 nm ( ∼ 4.28 eV ) of a natural K-rich feldspar crystal from Cáceres (Spain) has been studied using high sensitivity thermoluminescence (3D-TL) spectrometry. The spectral emission band has a Gaussian profile and could be linked with radiative electron–hole recombination in radiation-induced defect complexes. The glow curve shows a characteristic shape along the temperature axis, with an exponential rise ( E a = 0.98 ± 0.03 eV ) and a power-law decay (scaling exponent τ = 4.49 ± 0.09 at 2.5 °C/s heating rate). This characteristic profile is interpreted as a diffusion-activated luminescence phenomenon in which the trapping-detrapping-transition dynamics is controlled by local cooperative phenomena inside these complexes. The processes involved in the radiative recombinations could represent the reverse sequence of events occurring during defect formation by irradiation. The crystal lattice of this phosphor exhibits the capability of energy storage by luminescent centre formation because of its potential to self-structuring locally into well-organized structural complexes under irradiation. This structural capability must be considered as a systemic property.