Enhanced luminescence of novel Ca3B2O6:Dy3+ phosphors by Li+-codoping for LED applications

• Published in: Ceramics international Vol. 38; no. 2; pp. 1065 - 1070
• Main Authors: Sun, X-Y, Zhang, J-C, Liu, X-G, Lin, L-W
• Format: Journal Article
• Language: English
• Published: 01.03.2012
• Subjects: Ceramics; Excitation; Light-emitting diodes; Optimization; Phosphors; Photoluminescence; Spectra; White light
• ISSN: 0272-8842
• DOI: 10.1016/j.ceramint.2011.08.032

The Ca3-xB2O6:xDy3+ (x = 0.0-0.105) and Ca2.95-yDy0.05B2O6:yLi+ (y =0-0.34) phosphors were synthesised at 1100 C in air by a solid-state reaction route. The as-synthesised phosphors were characterised by XRD, SEM, photoluminescence excitation (PLE) and photoluminescence (PL) spectra. The PLE spectra showed excitation peaks from 300 to 400 nm due to the 4f-4f transitions of Dy3+. This mercury-free excitation is useful for solid state lighting and light-emitting diodes (LEDs). The emission of Dy3+ ions on 350 nm excitation was observed at 480 nm (blue) due to the 4F9/2 to 6H15/2 transitions, 575 nm (yellow) due to 4F9/2 to 6H13/2 transitions and a weak 660 nm (red) due to 4F9/2 to 6H11/2 emissions, respectively. The optimal PL intensity of the Ca3-xB2O6:xDy3+ phosphors was for x = 0.05. The PL results for Ca2.95-yDy0.05B2O6:yLi+ phosphors showed that Dy3+ emissions can be enhanced with the increasing codopant Li+ content until y = 0.22. To simulate white light, the CIE of the investigated phosphors can be tuned by varying the content of Li+ ions, and the optimal CIE value (0.300, 0.298) was realised when the content of Li+ ions was y = 0.22. All the results imply that the Ca2.95-yDy0.05B2O6:yLi+ phosphors could be potentially used as white LEDs.