Study On Ferroelectric Properties And Upconversion Luminescent Properties Of Rare Earth Doped BaTiO₃

Barium titanate material has excellent dielectric properties,piezoelectric properties and ferroelectric properties,it is widely applied to capacitors,sensors,memory and other electronic products,and it's known as the modern"electronic ceramic pillars."In order to meet the higher demand for materials science and technology,people began to try to modification of barium titanate material,such as decreasing the particle size,and compositing with organic materials,mixing impurities and so on.We can change the lattice structure of BaTiO₃ by doping to control the important physical properties such as dielectric constant and ferroelectric parameters,so that it can be put into a wider range of materials applications.Barium titanate also has good light transmission,stability and less phonon energy,can be used as the substrate for upconversion luminescent materials.If the rare earth element doped barium titanate material for its modification is used in combination with the upconversion luminescence properties of materials,or to find a corresponding law,it will be of great significance in three-dimensional image display and other fields.The main contents of this work are three points,the specific content is as follows:?1?The BaTiO₃ target was prepared by sol-gel method and target-making process.The optimum sintering temperature 1300?was determined by XRD,SEM and hysteresis loops.On the basis of this,the BaTiO₃:xEr³⁺samples?x=0,1%,2%,3%?doped with Er³⁺ions were prepared.The incorporation of Er³⁺ions could affect the lattice structure and macroscopic properties of BaTiO₃.With the increase of Er³⁺concentration,the diffraction peaks at 2?=45 degrees gradually merged,and the crystal form changed from tetragonal phase to cubic phase.The Er³⁺will enter the lattice to replace the ion radius of the larger Ba²⁺caused by lattice shrinkage,inhibition of grain growth,particle size and more uniform.Since the donor doping reduces the oxygen vacancy concentration,the coercive field Ec is reduced,and the movable distance of Ti⁴⁺is reduced,which is the reason why the remnant polarization intensity Pr increases first and then decreases.?2?Fabricated BaTiO3:xYb³⁺,yEr³⁺,zTm³⁺upconversion luminescent powders.The emission spectra were measured with an infrared laser at 980 nm and measured with a Hitachi F-4600 spectrometer.Yb3+is used to transfer energy as the sensitizer,The blue emission peak of 482nm is derived from ¹G₄?³H₆ transition of Tm³⁺ions,and the green emission peaks at 530nm and 551nm are from ⁴H_11/2/⁴S_3/2?⁴I_15/2 transition,respectively,at 661nm Of the red emission peak is accompanied by Er³⁺from the excited state ⁴F_9/2 energy level transition to the ground state ⁴I_15/2 issued.We try to change the relative ratio of three kinds of rare earth continuously to control the relative intensity of different emission peaks.Finally,the red,green and blue emission peaks with intensity close to 1:1:1 are obtained,and the CIE chromaticity diagram shows near white light.Finally,the mechanism of energy transfer between ions is analyzed.?3?BaTiO₃:Er³⁺films were prepared by sol-gel method and spin coating method,and the surface was covered with nano-Ag particles.SEM photographs show that nano-Ag particles are more evenly dispersed on the surface of the film.The emission spectra of the films before and after nano-Ag modification were measured by 980nm infrared laser,and the three emission peaks at 530,551,663nm were 23.3 times,22.7times and 14.8 times higher than before.We investigated the effect of metal plasma resonance on the fluorescence intensity of the upconversion thin film.Finally,we use a magnetron sputtering method to sputter a layer of pure BaTiO₃ layer on the surface of the film as a package to form a durable composite structure,effectively prevent the nano-Ag is oxidized and extended service life.