RADIATION-INDUCED LUMINESCENCE IMAGES AND TL-PROPERTY CHANGES WITH THERMAL ANNEALING TREATMENT ON JAPANESE TWIN QUARTZ

Two-dimensional patterns of radiation;induced phenomena, including the rmoluminescence (TL), after-glow (AG) and colour centre (CC) images, s howed significantly different behaviour between the core and outer par ts 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-receiv ed quartz slice segments revealed poor BTL sensitivity and a tendency to saturation at low doses. The outer parr was especially characterize d by high contents of both aluminium and OH impurity, although the ann ealing treatments greatly eliminated the OH concentrations as water va pour. The annealing treatment (50 hr at 1000 degrees C) of the slice s egments brought on a remarkable changes to the TL-property; the core p art was converted from BTL having a broad peak around 480 nm at 230 de grees C into a new BTL peak around 100 degrees C, and broad spectrum r anging from BTL to red TL (RTL) at 300 degrees C. The outer part was c haracterized by a change into a new single 100 degrees C BTL peak from some weak peaks of the as-received segment. On the basis of these rad iation-induced phenomena, a new formation mechanism for twin quartz is proposed. We propose that the core part was formed first and was foll owed by the formation of the out part from hydrothermal solution and w ith a higher aluminium concentration. (C) 1998 Published by Elsevier S cience Ltd. All rights reserved.