Study On Hydrothermal Synthesis And Luminescence Property Of ASnO₃:Eu³⁺?A=Ca,Sr,Ba? Nanocrystals

The alkaline earth metal stannate ASnO₃?A=Ca,Sr,Ba?is a typical luminescent matrix material.Europium ion doped stannate nanomaterials have attracted more and more attention due to excellent red light emission properties,good thermal stability and chemical stability.In this dissertation,three kinds of matrix materials,Ca SnO₃,SrSnO₃ and BaSnO₃ can be obtained as the main raw materials of Ca Cl₂,SrCl₂,BaCl₂ and Na₂SnO₃ by hydrothermal method.The effects of pH value,Eu³⁺ion doping amount,the amount of surfactant,reaction temperature and reaction time were studied on the phase,morphology and luminescence property of the products.The optimum conditions for the synthesis of ASn O₃?A=Ca,Sr,Ba?nanocrystals were determined by optimizing the reaction conditions.The main results were as follows:1.The CaSnO₃:Eu³⁺nanocrystals with perovskite structure were prepared at pH range of 10¹3.The mixture of calcium stannate and calcium oxide was prepared at pH=9.The optimum conditions for hydrothermal synthesis of CaSnO₃:Eu³⁺microspheres were as follows:the pH value of 12,the reaction temperature of 180?and the reaction time of 18 h.The morphology are microspheres in a diameter of 2.1?m².5?m.The microspheres are uniform with smooth surface.The product exhibited the most excellent luminescence property when the doping amount of Eu³⁺ions was 5%.2.SrSnO₃:Eu³⁺nanocrystals with perovskite structure were prepared at p H range of 9¹3.The optimum conditions for hydrothermal synthesis of SrSnO₃:Eu³⁺microspheres were as follows:the pH value of 12,the reaction temperature of200?and the reaction time of 24 h.The microspheres were 1.2?m¹.6?m and composed of nanoparticles.The luminescence property of the product was the most excellent at the Eu³⁺doping amount of 5%.3.The optimum conditions for perovskite BaSnO₃:Eu³⁺nanoparticles via hydrothermal process were as follows:the p H value of 12,the reaction temperature of 200?and the reaction time of 24 h.The products with Eu³⁺doping amount of15%exhibited the most excellent luminescence property.4.In comparison to three kinds of ASnO₃:Eu³⁺?A=Ca,Sr,Ba?nanocrystals prepared under the optimum conditions,the results showed that:?1?The XRD diffraction peaks of CaSnO₃,SrSnO₃ and BaSnO₃ crystals were similar.But the position of the diffraction peaks showed obviously a little shift,which was caused by the difference in the radius of alkali earth metal ions.?2?Under the optimum of adding Eu³⁺amount,the crystal plane spacing change??d?of ASnO₃?A=Ca,Sr,Ba?nanocrystals was compared.Eu³⁺ions were mainly doped on CaSnO₃?020?,?200?,?121?and?002?crystal planes.For SrSnO₃,Eu³⁺ions were mainly doped on?200?crystal planes.For BaSnO₃,Eu³⁺ions were mainly doped on?110?and?200?crystal planes.?3?The order of luminescence intensity for three crystals was:CaSnO₃>SrSnO₃>BaSnO₃.ASnO₃:Eu³⁺?A=Ca,Sr,Ba?nanocrystals of luminescence intensity was enhanced with the smaller the radius of alkali earth metal ions and the closer to the ionic radius of Eu³⁺ion.CaSnO₃:Eu³⁺nanocrystals showed higher luminescence intensity.It is possible that the radius of Ca²⁺and Eu³⁺ions is closest and the small change of the lattice structure was caused by Eu³⁺ion doping into CaSnO₃ crystal.