Down- and up-converting dual-mode YPO sub(4):Yb super(3+),Tb super(3+) nanocrystals: synthesis and spectroscopic properties

• Published in: Dalton transactions : an international journal of inorganic chemistry 2014-11, Vol.43 (46), p.17255-17264
• Main Authors: Grzyb, Tomasz, Wiglusz, Rafal J, Gruszeczka, Aleksandra, Lis, Stefan
• Format: Article
• Language: English
• Subjects: Coprecipitation; Excitation; Luminescence; Nanocrystals; Recording; Spectroscopy; Ultraviolet; Upconversion
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c4dt02234c

Tetragonal YPO sub(4) nanocrystals doped with Yb super(3+) and Tb super(3+) ions were synthesized by 900 degree C annealing of precursors obtained with a co-precipitation method in the presence of glycerine. These materials exhibited intense green luminescence under ultraviolet excitation and up-conversion emission from the super(5)D sub(3) and super(5)D sub(4) Tb super(3+) excited states after irradiation with near infrared light ( lambda = 980 nm). The structure and morphology of the products were analysed by recording X-ray diffraction patterns and transmission electron microscopy images. The obtained nanomaterials were single-phased with spherical shaped nanocrystals that had an average size of 18 plus or minus 3 nm. The spectroscopic properties of YPO sub(4):Yb super(3+),Tb super(3+) nanocrystals were investigated based on their excitation and emission spectra. The time-resolved luminescence traces were measured, and the luminescence lifetimes of Tb super(3+) and Yb super(3+) ions were calculated. The most effective dopant concentrations were determined to be 5% Yb super(3+) and 15% Tb super(3+), which exhibited the most intense ultraviolet excited emission and up-conversion. Because the integral intensity was observed to be dependent on the power of the pumping laser, a cooperative energy transfer (CET) mechanism underlying the observed up-conversion was proposed.