Radiation-induced luminescence images and TL-property changes with thermal annealing treatment on Japanese twin quartz

Abstract

Two-dimensional patterns of radiation-induced phenomena, including thermoluminescence (TL), after-glow (AG) and colour centre (CC) images, showed significantly different behaviour between the core and outer parts of a Japanese twin quartz slice. Intense smoky colouration and blue luminescence appeared in the core, giving a good inverse correlation with the distribution of aluminium impurity. In addition, there was a characteristic red AG in the outer parts of the crystal. The response to radiation of the blue TL (BTL) from the outer part of the as-received quartz slice segments revealed poor BTL sensitivity and a tendency to saturation at low doses. The outer part was especially characterized by high contents of both aluminium and OH impurity, although the annealing treatments greatly eliminated the OH concentrations as water vapour. The annealing treatment (50 hr at 1000°C) of the slice segments brought on a remarkable changes to the TL-property; the core part was converted from BTL having a broad peak around 480 nm at 230°C into a new BTL peak around 100°C, and broad spectrum ranging from BTL to red TL (RTL) at 300°C. The outer part was characterized by a change into a new single 100°C BTL peak from some weak peaks of the as-received segment. On the basis of these radiation-induced phenomena, a new formation mechanism for twin quartz is proposed. We propose that the core part was formed first and was followed by the formation of the out part from hydrothermal solution and with a higher aluminium concentration.