The Preparation Of SrTiO₃:Pr³⁺ Powders By Tartaric Acid Assisted Sol-gel Method And Study On The Enhancement Of Their Photoluminescence By Fluorhydric Acid Treatment

Rare earth Pr³⁺doped ABO₃ oxides have attracted considerable attention in recent years, which can emit red light under the low-energy electron or the ultraviolet excitation. It is a new kind of red phosphor, and the red photoluminescence (1D2→3H4 transition of Pr³⁺) is very close to that of the 'ideal red' of the CIE coordinate. As a result, the Pr³⁺ doped ABO₃ red phosphor can be used as the next generation of flat panel display technology——field emission display (FED). In this thesis, we prepared the Pr³⁺ and Al³⁺ co-doped SrTiO₃ nanoparticles, and tried to modify the red emission of Pr³⁺ through two aspects: preparation technology and HF treatment.At first, we prepared Sr0.998Pr0.002Ti1-xAlxO₃ phosphor by sol-gel method assisted with tartaric acid. The phosphor has narrow size and uniform distribution. The content of tartaric acid, the concentration of Al doping and the annealing temperature were investigated, and it was found that all of them had effect on the red photoluminescence. Even a small amount of tartaric acid could lead to the formation of pure phase SrTiO₃. Besides, we found that the favorite condition to achieve the superior red emission was as follows: (1) the molor ratio of the tartaric acid and metal ions is 2:1; (2) the concentration of Al doping is 2%; (3) the annealing temperature is 1000?C. The related work has been accepted by Material Chemistry and Physics.On the other hand, it was reported the oxygen vacancy can be produced by the HF treatment on the SrTiO₃ crystal, and the oxygen vacancy in SrTiO₃ stabilizes a self-trapped hole level within the band gap, leading to the blue emission at the room temperature. There is an obvious spectral overlap between the blue emission spectra of oxygen-vacancy and the excitation spectra of the red emission of Pr³⁺ ion, so the red emission of Pr³⁺ may be modulated through introducing oxygen vacancies into SrTiO₃. In this thesis, we HF-treated the Sr_0.998Pr_0.002Ti_0.98Al_0.02O₃ (SrTiO₃:Pr³⁺) powders and the study of the microstructure, grain size and photoluminescence was then performed. We found that the red emission intensity increased 18 times after 10 min treatment of HF. The increased red emission was ascribed to the oxygen vacancy produced after the HF treatment, and this oxygen vacancy made the energy transfer from SrTiO₃ host to Pr³⁺ and the red emission enhance. In addition, the red emission of the sample treated in the vacuum atmosphere increased about 4 times, indicating that HF treatment is a more effective method in improving the red emission of SrTiO₃:Pr³⁺ powders. The related study has been published on Journal of Luminescence.