Reduction of Eu3+ to Eu2+ in Ba1−yle='font-style: italic'>xSrxGd1−yle='font-style: italic'>yYyB9O16:Eu phosphor: Synthesis, composition controlling, and tunable luminescence
Eu2+ and Eu3+ codoping Ba1−xSrxGd1−yYyB9O16 phosphors are synthesized. Eu3+ ions are controllably reduced to Eu2+ by incorporating Sr2+ or Y3+ ion, and changing Eu3+ concentration. Tunable luminescence behaviors are explained according to site occupancy theory.