Acta Chim. Sinica ›› 2016, Vol. 74 ›› Issue (2): 191-198.DOI: 10.6023/A15040257 Previous Articles     Next Articles



黄清明a,b, 俞瀚a, 张新奇b, 曹文兵a, 俞建长a   

  1. a 福州大学 材料科学与工程学院 福州 350108;
    b 福州大学 测试中心 福州 350002
  • 投稿日期:2015-04-14 发布日期:2015-11-24
  • 通讯作者: 俞建长
  • 基金资助:


Upconversion Performance Enhancement of NaYF4:Yb/Tm by Codoping Hf4+ as Energy Migrator

Huang Qingminga,b, Yu Hana, Zhang Xinqib, Cao Wenbinga, Yu Jianchanga   

  1. a College of Materials Science and Engineering, Fuzhou University, Fuzhou, Fujian 350108;
    b Instrumentation Analysis and Research Center, Fuzhou University, Fuzhou, Fujian 350002
  • Received:2015-04-14 Published:2015-11-24
  • Supported by:

    Project supported by the Natural Science Fund of Fujian Province (No. 2013J05027).

In this paper we report the infrared to visible upconversion(UC) luminescence properties of Hf4+ and Zr4+ codoped NaYF4:Yb3+/Tm3+. Samples were synthesised by hydrothermal method. Concentration of Tm3+ and Yb3+ ions were fixed to be 2 mol% and 5 mol% for all samples, respectively. NaY0.93-xYb0.05Tm0.02F4 was tridoped with 0, 2, 4, 6, 8 mol% Hf4+ or Zr4+ and corresponding samples were named as Hf0, Hf2, Hf4, Hf6, Hf8 and Zr0, Zr2, Zr4, Zr6, Zr8, respectively. In a typical procedure, trivalent nitrate stock solutions of 0.2 mol/L were prepared at first by dissolving the corresponding metal oxide in concentrated nitric acid or hydrofluoric acid at elevated temperatures. And then, a certain mole percentage of trivalent nitrate solutions were added into 20 mL 0.04 mmol EDTA aqueous solution. After vigorous stirring for 30 min, 25 mL ethanol solution containing 0.2 mmol NaF, 0.2 mmol NH4HF2 and corresponding stoichiometric amount Hf4+ or Zr4+ were dropwise added into the solution, and then pH value of solution was adjusted to 3.0 by addition 1 mol/L HF, and stirring continued for 30 min. Then the emulsion mixture was moved to PTFE-lined high pressure pot and incubated in oven at 180℃ for 12 h. The final products were collected, washed several times with water and ethanol alternately, and gathered by centrifugation, and then dried in oven at 60℃. Crystal microstructure, morphology and UC luminescence properties of samples were investigated by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and upconversion photoluminescence spectra. Results revealed the bond distance of F1-Y and F2-Y become close with the rising of Hf4+ or Zr4+ codoped concentration, indicating crystal field asymmetry of rare earth ions were tuned effectively by Hf4+ or Zr4+ codoping. Electron hypersensitive transition was promoted, and the intensity of 802 nm emission was enhanced obviously. Hf4+ ion was a better dopant than Zr4+, for the extranuclear electronic structure of Hf4+ was the same with rare earth ions, and Hf4+ ion was involved in UC process as a migrator to improve Tm3+ upper state levels'population. UC luminescence of Hf4+ codoped sample were enhanced obviously, especially the shortwave emissions. The reported work establishes the understanding of Hf4+ as a migrator for Tm3+ ions upconversion luminescence, which may be helpful for design and synthesis of high-performance upconversion materials.

Key words: upconversion, hafnium doping, crystal field, energy migration