Upconversion emission tuning from green to red in Yb3+/Ho3+-codoped NaYF4 nanocrystals by tridoping with Ce3+ ions

• Published in: Nanotechnology Vol. 20; no. 38; p. 385704
• Main Authors: Chen, Guanying, Liu, Haichun, Somesfalean, Gabriel, Liang, Huijuan, Zhang, Zhiguo
• Format: Journal Article
• Language: English
• Published: England IOP Publishing 23.09.2009
• Subjects: Algorithms; Cesium - chemistry; Fluorides - chemistry; Fluorine - chemistry; Holmium - chemistry; Iodine - chemistry; Lasers; Luminescent Measurements; Metal Nanoparticles - chemistry; Microscopy, Electron, Transmission; Models, Chemical; Spectroscopy, Near-Infrared; Sulfur - chemistry; X-Ray Diffraction; Ytterbium - chemistry; Yttrium - chemistry
• ISSN: 0957-4484; 1361-6528
• DOI: 10.1088/0957-4484/20/38/385704

Upconversion (UC) emission tuning from green to red in monodisperse NaYF(4):Yb(3+)/Ho(3+) nanocrystals was successfully achieved by tridoping with Ce(3+) ions under diode laser excitation of 970 nm. It is proposed that two efficient cross-relaxation processes, 5S2/5F4(Ho) + 2F(5/2)(Ce) --> 5F5(Ho) + 2F(7/2)(Ce) and 5I6(Ho) + 2F(5/2)(Ce) --> 5I7(Ho) + 2F(7/2)(Ce)between Ho(3+) and Ce(3+) ions, have been employed to select UC pathways to tune the UC radiation. Theoretical investigations based on steady-state equations demonstrate the proposed UC mechanisms and explain well the observed linear increase of the UC red-to-green intensity ratio with the increment of Ce(3+) ion concentrations.