TOF SIMS analysis and enhanced UVB photoluminescence by energy transfer from Pr3+ to Gd3+ in Ca3(PO4)2:Gd3+,Pr3+ phosphor prepared by urea assisted combustion

• Published in: Journal of alloys and compounds Vol. 595; pp. 33 - 38
• Main Authors: Mokoena, P.P., Gohain, M., Kumar, V., Bezuidenhoudt, B.C.B., Swart, H.C., Ntwaeaborwa, O.M.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 15.05.2014; Elsevier
• Subjects: Combustion method; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Phosphor; Photoluminescence; Physics; TOF-SIMS; UVB radiation; Combustion method; UVB radiation; TOF-SIMS; Phosphor; Photoluminescence; Scanning electron microscopy; Combustion synthesis; Calcium phosphate; XRD; Secondary ion mass spectra; Phosphors; Gadolinium additions; Praseodymium additions; Excitation spectrum; Energy transfer; Codoping
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2014.01.088

•The influence of urea in the crystallinity of Ca3(PO4)2.•The influence of Gd3+ and Pr3+ doping on the particle morphology.•Specific elemental topography of each individual ions distributed across the surface.•The importance of using specific concentration of Pr3+ for efficient energy transfer. Ca3(PO4)2:Gd3+,Pr3+ phosphors with different concentrations of Gd3+ and Pr3+ were prepared by combustion process using metal nitrates as precursors and urea as fuel. The phosphors were characterized by X-ray diffraction (XRD), Scanning electron microscopy, Time of Flight-Secondary Ion Mass Spectrometry, ultraviolet–visible and photoluminescence (PL) spectroscopies. The XRD patterns were consistent with the standard rhombohedral phase of Ca3(PO4)2 referenced in JCPDS Card No. 70-2065. The average crystallite size calculated using the Scherrer equation at different urea masses was in the range of ∼60–120nm. The PL excitation spectra of Ca3(PO4)2:Gd3+ and Ca3(PO4)2:Pr3+ exhibited peaks at 220–280 and 300–490nm associated with the f→f transitions of Gd3+ and Pr3+ respectively. The ultraviolet B (UVB) emission resulting from the 6P7/2→8S7/2 transition of Gd3+ was observed at 313nm when the Ca3(PO4)2:Gd3+ phosphor was excited at a wavelength of 274nm using a monochromatized xenon lamp. Upon Pr3+ co-doping, the excitation peaks due to Gd3+ and Pr3+ f→f transitions were suppressed and an intense broad excitation peak ascribed to the 4f→4f5d transitions of Pr3+ was observed at 227nm. The peak intensity of the UVB emission at 313nm was shown to improve considerably when the Gd3+ and Pr3+ co-doped systems were excited at the wavelength of 227nm suggesting that the Pr3+ is a good sensitizer of the 313nm narrow line UVB emission from Gd3+.