On the luminescence emission band at 340 nm of stressed tectosilicate lattices

A 340 nm emission peak in the luminescence spectra of tectosilicate minerals, e.g., groups of silica, feldspars, feldspathoids, could be observed when the three-dimensional (3D)-framework silicon–oxygen lattices is stressed. The Si–O strained structures include some non-bridging oxygen or silicon vacancy-hole centers, and Si–O bonding defects which seem to be responsible for the 340 nm emission. This paper presents luminescence spectra from a cross-hatch microcline with natural metastable stress and includes data from analyses using spectra from thermoluminescence (TL), cathodoluminescence (CL), radioluminescence (RL), infrared-stimulated luminescence after X-irradiation (IRSL) and ionoluminescence (IL). The following features and examples imply why stress of tectosilicate lattices can be linked to the luminescence emission at 340 nm: (i) natural metastable hatch-cross texture in exsolved Na/K microcline at 300 K, (ii) radiation damaged areas in natural quartz, (iii) natural quartz with large amounts of silicon substitution with aluminum and alkali ions, (iv) artificial porous silica with OH groups adsorbed to the surfaces, (v) sodalite feldspathoid in which many tetrahedral silicon Si4+ are substituted with intrinsic aluminum–chlorine defects, (vi) IL at low temperature of all tectosilicate analyzed samples enhanced the 340 nm peak. The ion beams always produce the 340 nm emission at 40 K in feldspar samples (K-feldspar and Na-feldspar), silica (e.g., quartz and tridymite) and feldspathoids (sodalite). The final conclusion, for tectosilicate 3D lattices, is that there is a correlation between the 340 nm luminescence emission band and stressed Si–O bonds.