Hydrothermal Synthesis And Luminescence Properties Of Rare Earth Doped Strontium Titanate Nanopowders

With unique chemical stability,thermal stability and unique perovskite structure,strontium titanate(SrTiO3)has been widely used in many fields as a functional powder material.With the development of science and technology,the higher requirement for particle size and purity of strontium titanate powder,the more in-depth research on the preparation of high purity strontium titanate powder has been made.As a functional material,strontium titanate with unique structure can be wildely applied in practical engineering fields by doping of foreignions.For example,it has wide application in the firld of luminescence by rare earth ions doping.In this paper,Er3+,Yb3+and Eu3+co-doped SrTiO3 were used to obtain phosphors with good luminescent properties,which provided information for LED luminescent materials.Strontium titanate nanopower was prepared by hydrothermal experiment,the hydrothermal reactor of hydrothermal synthesis equipment is designed and simulated to make it meet the safety standard of experimental use.And the optimal scheme was obtained by orthogonal design in this work,he reaction temperature,reaction time,mineralizer concentration and the influencing factors of surfactant were analyzed by control variable method.The phase analysis and morphology analysis of the samples were carried out by means of XRD and SEM.Experimental results indicated that high purity strontium titanate powder about 35nm can be obtained when the reaction temperature was below 140?,the reaction temperature was about 20h,the mineralizer concentration was 1.8mol/L,the concentration of surfactant was 9vol.%,strontium nitrate was used as Sr source,and tetrabutyl-titanate was used as Ti source.Next,strontium titanate powder was modified by rare earth ions introduce,and its luminescence properties were also investigated,Similar to the preparation method of the pure strontium titanate,hydrothermal experiment was still used to prepare strontium titanate powder doped with Eu3+,Eu3+and Er3+,Eu3+and Yb3+,The phase structure,morphology,luminescence properties and fluorescence lifetime of strontium titanate doped with rare earth ions were studied.The results showed that the phase structure of the titanium titanate powder was not changed for the rare earth ions introducing,and the titanium titanate powder showed excellent red fluorescence characteristics when the optimum doping concentration of Eu3+ is 7mol%.The results show that Eu3+ occupies not only the inversion-free central lattice(5D0?7F2)but also the strict inversion central lattice(5D0?7F1)in strontium titanate.Under the optimal doping concentration of Eu3+,the doping of Er3+is tested and analyzed.Er3+ ions was introduced into the titanium titanate doped with 7mol%Eu3+,and analysis indicated that Er3+ ions doping can further imporve the luminescent properties.This is because Er3+absorbs excitation radiation and transfers energy to Eu3+,which makes its luminescence intensity higher.With the increase of concentration,the distance between Er3+ decreases,which hinders the energy transfer between Er3+ and Eu3+ and leads to the decrease of luminescence,and the optimum doping concentration of Er3+ is 1mol%.Yb3+ is doped at the optimum doping concentration of Eu3+ and the luminescence performance is the best when the doping concentration of Yb3+ is 3mol%.This is due to the formation of a pair of virtual excitation states of Yb3+which can transfer energy to Eu3+and enhance its luminescence.