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 Ca_0.75Sr_0.2Mg_1.05Si₂O₆ (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:xCe³⁺ 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.