Optical properties of Eu 2+ /Eu 3+ mixed valence phosphor Ca 2 SiO 2 F 2 :Eu 2+ /Eu 3 .

The Eu2+ /Eu3+ mixed valence phosphor Ca2 SiO2 F2 :Eu2+ /Eu3+ was prepared using a solid-state reaction synthesis method in a CO atmosphere, and the optical properties were investigated. The spectroscopic properties revealed that Ca2+ ions were occupied by both Eu2+ and Eu3+ ions in Ca2 SiO2 F2 , and both ions were able to generate their characteristic emissions. A broad 5d → 4f Eu2+ band at ~470 nm and narrow 4f → 4f Eu3+ peaks upon excitation with n-UV light were observed. The ratio between Eu2+ and Eu3+ emissions changed regularly, and the relative intensity of the red component from Eu3+ became systematically stronger with increasing overall Eu content. As a result, the emission color of these phosphors can be tunable from blue to pink under n-UV light excitation.