Synthesis and upconversion luminescence properties of NaYF4：yb^3＋/Er^3＋ microspheres

• Published in: Journal of rare earths Vol. 27; no. 3; pp. 395 - 398
• Main Author: 王国风 秦伟平 王丽丽 尉国栋 朱培芬 张代生 丁福恒
• Format: Journal Article
• Language: English
• Published: 2009
• Subjects: 上转换发光特性; 上转换荧光; 乙二胺四乙酸; 双光子过程; 激光光子; 激发过程
• ISSN: 1002-0721; 2509-4963

Cubic NaYF4：Yb^3＋（20%）/Er^3＋（1%） microspheres were synthesized by EDTA-assisted hydrothermal method. Under 980 nm excitation, ultraviolet （^4G11/2→^4I15/2）, violet （^2H9/2→^4I15/2）, green （^4F7/2→^4I15/2, 2H11/2→^4I15/2, and ^4S3/2→^4I15/2）, and red （^4F9/2→^4I15/2） upconversion fluorescence were observed. The number of laser photons absorbed in one upconversion excitation process, n, was determined to be 3.89, 1.61, 2.55, and 1.09 for the ultraviolet, violet, green, and red emissions, respectively. Obviously, n=3.89 indicated that a four-photon process was involved in populating the ^4G11/2 state, and n=2.55 indicated that a three-photon process was involved in populating the ^4F7/2/^2H11/2/^4S3/2 levels. For the violet and red emissions, the population of the states ^2H9/2 and ^4F9/2 separately came from three-photon and two-photon processes. The decrease of n was well explained by the mechanism of competition between linear decay and upconversion processes for the depletion of the intermediate excited states.