Sonoluminescence of X-ray irradiated KCl:Ca2+ during deformation

We have observed luminescence stimulated by the application of ultrasonic oscillation during plastic deformation of X-ray irradiated KCl single crystals doped with Ca2+. The luminescence intensity rapidly increases at the beginning of plastic deformation. The intensity remains roughly constant for a while and is then followed by gradual decrease. The variation of luminescence intensity seems to correspond to the deformation stage of the crystal. Superposition of oscillation during plastic deformation of crystals causes a decrease in deformation stress along with additional luminescence (sonoluminescence, SL). The SL intensity also appears to correspond to the deformation stage. The SL intensity increases proportionally with increasing stress decrement, which is approximately proportional to the amplitude of oscillatory stress. No amplitude dependence of internal friction during deformation has been observed. Thus, the SL intensity is not likely to be directly affected by internal friction.