Luminescent properties of Eu-doped germanate apatite Sr2La8(GeO4)O2

• Published in: Journal of alloys and compounds 2006-06, Vol.416 (1-2), p.199-205
• Main Authors: LI, Yu-Chun, CHANG, Yen-Hwei, TSAI, Bin-Siang, CHEN, Yu-Chung, LIN, Yu-Feng
• Format: Article
• Language: English
• Subjects: 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; Other solid inorganic materials; Photoluminescence; Physics
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2005.08.025

The photoluminescence properties of Eu-doped Sr2La8(GeO4)6O2 were investigated by measuring emission and excitation spectra, and decay curves. The Eu3+ ions were found to occupy two cationic sites labeled La(2) and Sr(l). The dominant sites La(2) occupied by Eu3+ ions shows strong red emission (5D0 - > 7F2 transition) at 613 nm. The Eu3+ ions incorporated into the subordinate sites Sr(l) produces strong orange emission (5D0 - > 7F1transition) at 589 nm. This would be responsible for the charge-compensating mechanism, in which inversion symmetry is evident around the europium ions. The concentration quenching behaviors of excitation under CTS and intra-4f energy levels are different. The emission intensity decreases at the onset of about 15 mol% Eu3+ concentration under the excitation at CTS, and the saturation of emission intensity excited by intra-4f transitions occurs at a concentration of 50 mol% Eu3+. The maximum photoluminescence intensity of excited at intra-4f transitions is about a factor of 10 times brighter than that excited at CTS.