中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 33 No. 4 April 2023 |
（1. Key Laboratory for Functional Materials Chemistry of Guizhou Province, School of Chemistry and Materials Science, Guizhou Normal University, Guiyang 550001, China;
2. Institute of Education, Guizhou Normal University, Guiyang 550001, China;
3. Guangxi Key Laboratory of Agricultural Resources Chemistry and Biotechnology, College of Chemistry and Food Science, Yulin Normal University, Yulin 537000, China）
Abstract:Ho3+ and Yb3+ co-doped La7P3O18 up-conversion phosphors were prepared by a high-temperature solid-state process. XRD results reveal that the samples are mixtures of monoclinic structure La7P3O18 crystals with P21/n space group and minor LaPO4 crystals. UV-Vis DRS results indicate that La7P3O18 crystal is an indirect semiconductor with an optical band gap of 4.10 eV. After 980 nm laser excitation, the Ho3+ and Yb3+ co-doped La7P3O18 phosphors show the characteristic blue (486 nm), green (550 nm), and red (661 nm) luminescence peaks of Ho3+ ions. The peak at 661 nm dominates in the up-conversion luminescence spectra of samples. Meanwhile, with the increase of Ho3+ and Yb3+ doping content, the up-conversion luminescence intensity increases first and then decreases. By increasing the doping contents of Ho3+ and Yb3+ up to 1 at.% and 10 at.%, respectively, concentration quenching may appear by an electric quadrupole- electric quadrupole interaction process. The pumping power dependence of luminescence indicates that the green and red emissions of samples are excited by a two-photon absorption process. The color coordinates of Ho3+ and Yb3+ co-doped La7P3O18 crystals locate in the orange-red region.
Key words: La7P3O18; Ho3+; Yb3+; up-conversion luminescence
