Excitation of triboluminescence by deformation of single crystals

The excitation of triboluminescence by elastic and plastic deformation and by fracture of single crystals has been studied in detail by means of a high sensitive experimental apparatus. Typical results are reported for crystals of ZnS(Mn), NaCl(Mn), X-ray-irradiated KI and KCl, and sugar. The experiments show that the characteristic light peaks of triboluminescence are intimately related to the treads occurring in the stress–strain curves. A detailed analysis of these curves in different materials suggests two excitation mechanisms for triboluminescence: 1. excitation by impact of moving dislocations with trapped electrons; 2. excitation by unpinning of dislocations from luminescent centres.