NaYF_4∶Yb,Er/Tm上转换发光强度的影响因素

含有稀土离子的上转换发光材料因具有巨大的应用价值而受到人们的广泛研究,特别是六方相NaYF4已被公认为是迄今为止发光强度最大的上转换基质材料.以稀土离子Yb和Er或Yb和Tm的共掺杂NaYF4上转换材料为研究对象,讨论了几种不同因素对其上转换发光强度的影响,并对这种上转换材料的应用与研究前景提出了几点建议.     

Preparation and characterization of upconversion nanocomposite for β-NaYF_4:Yb~(3+),Er~(3+)-supported TiO_2 nanobelts

Hexagonal NaYF4:Yb3+,Er3+ (β-NaYF4:Yb3+,Er3+) nanoparticles supported on TiO2 nanobelts were prepared using two-step pro- cedures of ion-exchangeable process and hydrothermal treatment: layered titanate nanobelts were first ion-exchanged with Y3+, Yb3+ and Er3+ cations to produce titanate nanobelts with these cations, and then, the product nanobelts in NaY solution were treated under hydrothermal con- dition to transform into anatase TiO2 nanobelts supported with β-NaYF4:Yb3+,Er3+ nanoparticles. The final products were characterized by various measurement techniques. Many preparation conditions, e.g., the content of added precursors, reaction time and pH value, were optimized to obtain nanocomposites including relatively uniform nanoparticles with strong upconversion (UC) emission intensity. The measurement results showed that the anatase TiO2 nanobelts, supported by the large number of β-NaYF4:Yb3+,Er3+ nanoparticles with 30–70 diameter range and very strong UC emission, could be achieved under suitable preparation condition. The UC emission intensity of the nanoparticles with the concentrations of Yb3+ and Er3+ closer to 20 mol.% and 1 mol.% was the strongest.