Synthesis and luminescence properties of CaSnO :Bi blue phosphor and the emission improvement by Li ion.

CaSnO :Bi blue-emitting phosphor was synthesized using a high-temperature solid-state reaction method in air. The crystal structures and luminescence properties were investigated. A broad emission band peaking at ~448 nm upon excitation at 262 and 308 nm was observed in the range 330-680 nm at room temperature due to P  →  S transition of the Bi ion. The chromaticity coordinate was (0.1786, 0.1665). The optimal Bi ion concentration was ~0.6 mol% in CaSnO :Bi phosphor. The emission spectrum of CaSnO :Bi phosphor showed a blue-shift with increasing temperature from 50 to 300 K due to the influence of temperature on the electron transition of the Bi ion. The emission intensity of CaSnO :Bi phosphor may be increased ~1.45 times by co-doping Li ions as a charge compensator and fluxing agent. The luminescence mechanism is explained by a configurational coordinate diagram of Bi ion in CaSnO :Bi phosphor.