Luminescence mechanism of self-activated phosphor Ca0.75Sr0.2Mg1.05Si2O6 and abnormal second concentration quenching phenomenon of Ca0.75Sr0.2Mg1.05Si2O6:Ce3+

Luminescence mechanism of self-activated phosphor Ca0.75Sr0.2Mg1.05Si2O6 (CSMS) originating from oxygen vacancy defects has been deeply investigated by regulating synthesis temperature. The results demonstrate that the luminescence comes from three different oxygen defects in the crystal structure. For Ce3+ doped CSMS (ICSD#68180), two concentration quenching phenomena can be observed at x = 0.03 and 0.12 as the result of the formation of new substance CaMgSi2O6 (ICSD#17043), which leads to the actual concentration of Ce3+ in CSMS (ICSD#68180) is far less than the doping concentration since part of Ce3+ ions enter CaMgSi2O6 (ICSD#17043). The emission spectra of CSMS:xCe(3+) shifts from 388 nm to 405 nm with increasing Ce3+ content, which mainly should be due to the 5d energy center of Ce3+ shifting down and the crystal field split.