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Phase Transformation in Ca3(PO4)2:Eu2+ via the Controlled Quenching and Increased Eu2+ Content: Identification of New Cyan-Emitting α-Ca3(PO4)2:Eu2+ Phosphor
- Source :
- Journal of the American Ceramic Society; Oct2015, Vol. 98 Issue 10, p3280-3284, 5p, 1 Diagram, 1 Chart, 4 Graphs
- Publication Year :
- 2015
-
Abstract
- 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 Eu<superscript>2+</superscript>-doped α form Ca<subscript>3</subscript>( PO<subscript>4</subscript>)<subscript>2</subscript> (α- TCP:Eu<superscript>2+</superscript>) 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 Eu<superscript>2+</superscript> 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 P2<subscript>1</subscript>/ a, α- TCP) and the rhombohedral structure (space group R3 c, β- TCP), respectively. Upon 365 nm UV light excitation, α- TCP:Eu<superscript>2+</superscript> exhibits an asymmetric broad-band cyan emission peaking at 480 nm, while β- TCP:Eu<superscript>2+</superscript> displays a relatively narrow-band blue emission peaking at 416 nm. The Eu<superscript>2+</superscript>-doping in Ca<subscript>3</subscript>( PO<subscript>4</subscript>)<subscript>2</subscript> 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:Eu<superscript>2+</superscript> were compared in the aspects of compactness and cation site sets. The emission thermal stability of α/β- TCP:Eu<superscript>2+</superscript> was comparatively characterized and the difference was related to the specific host structural features. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00027820
- Volume :
- 98
- Issue :
- 10
- Database :
- Complementary Index
- Journal :
- Journal of the American Ceramic Society
- Publication Type :
- Academic Journal
- Accession number :
- 110163855
- Full Text :
- https://doi.org/10.1111/jace.13787