Luminescence of alpha-quartz

TL;DR

This paper reviews the luminescence properties of alpha-quartz, focusing on self-trapped excitons, defect-related emissions, and impurity effects, highlighting how irradiation and ion exchange influence luminescence behavior.

Contribution

It provides a comprehensive analysis of various luminescence mechanisms in alpha-quartz, including impurity and defect-related emissions, and how ion exchange modifies these properties.

Findings

STE luminescence at 2.6-2.7 eV observed under ionising radiation

Defect luminescence at 5 eV appears after heavy irradiation at low temperatures

Noble ion doping introduces new luminescence bands at 3.4 eV and 4.75 eV

Abstract

Among the host materials luminescence the luminescence of the self-trapped exciton (STE) is reviewed. This luminescence, which band is situated at 2.6 to 2.7 eV, could be observed mainly under ionising radiation with energetic yield about 0.2. The STE does not participate in pure recombination processes. Host material defect luminescence at 5 eV appears in alpha-quartz after heavy irradiation. It is constituted of permanent defect after neutron irradiation and transient defect after dens electron beam irradiation. This luminescence could be observed well at temperatures below 60 K. All another luminescence are of impurity nature. The Ge impurity luminescence in alpha-quartz explained as STE near Ge. The aluminium and alkali complexes. One of them is with UV band at 6 eV, appears at low temperatures and could be excited only in tunnelling recombination process between pairs (AlO4 Me), where Me is an alkali ion captured an electron and a hole remains on aluminium tetrahedron. Another luminescence with band at 3.4 eV is also luminescence of complexes (AlO4 Me), which behaviour is similar to the luminescence of alkali alumosilicate glass. The third luminescence with band at 3 eV could be observed mainly in natural alpha-quartz, bright at temperatures below 200 K and is interpreted as STE like luminescence at alumosilicate clasters. The exchange of alkali ions to noble ions of copper of silver reduces original luminescence of alumo alkali complexes and luminescence of noble ions appears. The main band of copper related luminescence is at 3.4 eV and that of silver is at 4.75 eV, both could be observed up to 500 K. their nature could be well described in terms of intraions transition. Exchange of noble ions back to alkali ions renews initial luminescence of the samples.