The site occupation of protons in lithium niobate crystals Original Research Article

A detailed study of sonoluminescence (SL) in ZnS bulk and powdered materials is presented. It is argued that high-frequency vibrations of dislocations in acoustic fields constitute the specific mechanism of a light production related to point defects and complexes of the defects generated by an acoustic wave. The SL spectra in bulk ZnS samples are found to originate from the defect complex (VZn−,Ac) of a zinc vacancy and a single-charged acceptor in a cation site. The computed energy levels are in excellent agreement with the experimentally observed SL peaks at about 512, 526, 540 and The SL peak at 500 nm is suggested to arise from the radiative transitions of free electrons to the energy band formed by moving dislocations. The defect related emissions are partially responsible for the SL bands in powdered ZnS materials whereas the broadness of the SL spectra can be explained in the framework of radiative transitions of free electrons within the conduction band. Possible applications of the phenomenon of crystal SL are outlined.