Defect Induced Photoluminescence and Triboluminescence in Layered CaLaAl3O7
In this work, a layered melilite structure, CaLaAl3O7, was synthesized and observed to have obvious luminescent behaviors under the stimuli of ultra-violet light and rubbing, which were called photoluminescence and triboluminescence, respectively. Considering the wide bandgap of CaLaAl3O7 as well as its specific crystal structure, the observed luminescence should be attributed to the intrinsic defects. Both the photoluminescence and triboluminescence of CaLaAl3O7 show a strong dependence on the synthesis atmosphere, suggesting that they should relate to the oxygen vacancy. It is attractive to find that the triboluminescence of CaLaAl3O7 shows a distinct spectral characteristic compared to its photoluminescence. Further computational results suggest that the applied mechanical stimuli on CaLaAl3O7 cell could promote the formation of vacancies of oxygen and calcium, responsible for the spectral differences.