A double perovskite Ca2MgWO6:Bi3+ yellow-emitting phosphor: Synthesis and luminescence properties

Novel double perovskite Ca2MgWO6:Bi3+ (CMW:Bi3+) yellow-emitting phosphor is synthesized by solid-state reaction method in air. Host Ca2MgWO6 with excitation 297 nm emits blue light and the chromaticity coordinate is (0.169, 0.160). The spectroscopic properties of CMW:Bi3+ phosphor are explained on the basis of the Bi3+ (6s2)-W6+ (5d0) metal-to-metal charge transfer (MMCT) transition. CMW:Bi3+ phosphor with excitation 338 nm shows yellow light and the chromaticity coordinate is (0.383, 0.477). Broad emission band peaking at ~550 nm of CMW:Bi3+ phosphor is observed in the range of 400-780 nm due to the D → 1S0 radiative decay and the 3P1,0 → 1S0 transitions of Bi3+ ion. Monitored at 550 nm, excitation spectrum of CMW:Bi3+ phosphor including a strong excitation peak at ~338 nm covers the region from 200 to 400 nm owing to the Bi3+ → W6+ MMCT transition and the 1S0 → 3P1 transition of Bi3+ ion. The optimal Bi3+ ion actual content is ~0.38 mol%. Emission spectra of CMW:Bi3+ phosphor with excitation 338 nm shows blue-shift with increasing temperature from 50 to 300 K owing to the influence of temperature to electron transfer. The possible luminous mechanism of CMW:Bi3+ phosphor is analyzed by energy level diagram of Bi3+ ion in solid including d0 cation.