Up-conversion Luminescent Properties Of Rare-Earth Doped Tio₂ Synthesized

Up-conversion luminescent nano-materials have been widely used in up-conversion lasers, biomedical and other fields. However, up-conversion luminescence efficiency problems make the development restricted in the broader field, therefore, the study of nano-materials which contain high chemical stability and up-conversion luminous efficiency will be high-tech materials research focus. TiO₂ has excellent chemical, optical properties, high thermal conductivity, larger thermal expansion coefficient and lower phonon energy, which is a good conversion matrix material, but its efficiency is lower than in the emission of fluoride materials, so improving the TiO₂ up-conversion luminescence efficiency will be a major research directions. In this article the up-conversion luminescence properties of rare-earth ions were discussed under a 980nm excitation in TiO₂ as a conversion matrix material. The up-conversion luminescence effects of the factors which were rare-earth doped Er³⁺ concentration, heat treatment temperature, Yb³⁺ concentration and the pump power, and Li⁺ doping on the TiO₂:Er³⁺/Yb³⁺ luminescence enhancement were discussed, as follows:1. TiO₂:Er³⁺ up-conversion nano-power was prepared by sol-gel method. The green (527⁵68nm) and red (641⁶80nm) emission have been observed under the excitation of 980nm. The influences of Er³⁺ concentration and heat treatment temperature on up-conversion luminescence are discussed.2. TiO₂:Ho³⁺/Yb³⁺ up-conversion nano-power was prepared by sol-gel method. The green (544⁵67nm) and red (650⁶80nm) emission have been observed under the excitation of 980nm. The influences of Yb³⁺ concentration on up-conversion luminescence are discussed. 3. TiO₂:Er³⁺/Ho³⁺/Yb³⁺ up-conversion nano-power was prepared by sol-gel method. The green (550nm) and red (660nm) emission have been observed under the excitation of 980nm, and the green intensity is stronger than the red. The influences of the pump power on up-conversion luminescence are discussed.4. Li⁺ doping TiO₂:Er³⁺/Yb³⁺ up-conversion nano-power was prepared by hydrothermal method. The green (546⁵67nm) and red (650⁶80nm) emission have been observed under the excitation of 980nm, and the red intensity is stronger than the green. The influences of Li⁺ doping on up-conversion luminescence are discussed. Furthermore, the influences of Li⁺ doping on size, morphology of nano-particle are investigated by using X-ray diffraction, scanning electron microscopy, up-conversion apparatus.