E-catalog        

Библиогр.: 23 назв.

A case of phosphor is reported where the cooling rate parameter significantly influences the luminescence property. By quenching the sample after the high-temperature solid-state reaction at 1250°C, we successfully prepared the Eu2+-doped α form Ca3(PO4)2 (α-TCP:Eu2+) as a new kind of bright cyan-emitting phosphor. The unusual emission color variation (from cyan to blue) depends on the cooling rate after sintering and Eu2+ doping level as it was observed in the TCP-based phosphors. By the Rietveld analysis, it is revealed that the cyan- and blue-emitting phosphors are two different TCP forms crystallizing in the monoclinic (space group P21/a, α-TCP) and the rhombohedral structure (space group R3c, β-TCP), respectively. Upon 365 nm UV light excitation, α-TCP:Eu2+ exhibits an asymmetric broad-band cyan emission peaking at 480 nm, while β-TCP:Eu2+ displays a relatively narrow-band blue emission peaking at 416 nm. The Eu2+-doping in Ca3(PO4)2 shifts the upper temperature limit of the stable structural range of β form from 1125°C to ≥1250°C. Moreover, the crystal structures of α/β-TCP:Eu2+ were compared in the aspects of compactness and cation site sets. The emission thermal stability of α/β-TCP:Eu2+ was comparatively characterized and the difference was related to the specific host structural features.