Deformation luminescence of X-ray-irradiated KCl:Eu2+ single crystals by compression

A new peak appears around 330 K on the thermoluminescence (TL) glow curve under the influence of compressive deformation for X-ray-irradiated KCl:Eu2+ (0.02 mol%) crystal. This new peak is termed 330 K peak here. Deforming the crystal by the compression, mechanoluminescence intensity varies according to the three-stage strain hardening of stress-strain curve and depends on dislocation motion during plastic deformation of the crystal. The 330 K peak is also variable with strain in accordance with the variation of stress and correlates with dislocation motion in the crystal. Analysing the data on F- and thermal-bleaching effects of the compressed crystal, the colour centre on the 330 K peak has a new energy-band near F-band. The TL spectrum of the compressed and subsequent X-ray-irradiated KCl:Eu2+ crystal has a peak of 420 nm at the 330 K peak. From this experimental result, it is deduced that the 330 K peak relates to the excited Eu2+ ions as the origin of luminescence.