Preparation And Photoelectric Properties Of Lead-free Electronic Energy Storage Ceramics

Ceramic dielectric material has the advantages of high power density,microsecond charge and discharge speed,high temperature and frequency stability,green safety and reliability,and is considered as the best energy storage dielectric material in the 21st century.Current pulse power equipment has been widely used in fields such as military defense,commercial and modern industry,with the rapid development of every field,to the requirement of pulse power equipment also gradually rise,the ceramic material is the key device in the pulse power devices,therefore,the storage performance of the ceramic material and under different environmental performance stability of the demand is higher and higher.However,the general energy storage density and voltage resistance of ceramic dielectric capacitors are still relatively low at present.Therefore,it is urgent to find dielectric ceramic materials with higher energy storage efficiency and energy density.Bi_0.5Na_0.5TiO₃based ceramic material is the representative material of lead-free energy storage capacitor medium due to its high polarization strength,high pressure resistance and unique transmittance of K_0.5Na_0.5NbO₃based ceramic material.In this paper,the two matrix materials will be selected to develop ceramic materials with high energy storage density and high energy density through doping modification.The specific research contents are as follows:Adopt SrSc_0.5Nb_0.5O₃and(Bi_0.5Na_0.5)(Ti_0.95Al_0.025Nb_0.025)O₃solid solution to build a new system of lead-free ceramics（1-x）(Bi_0.5Na_0.5Ti_0.95Al_0.025Nb_0.025O₃)-x(SrSc_0.5Nb_0.5O₃)（abbreviated as（1-x）BNTA-x SSN,x=5mol%,10mol%,15mol%,20mol%）.The effects of SrSc_0.5Nb_0.5O₃on the grain structure,phase structure,energy storage and dielectric properties of BNTA based ceramics were studied by traditional solid-state reaction method.The XRD and EDX measurements of（1-x）BNTA-x SSN ceramics show that SrSc_0.5Nb_0.5O₃is successfully dissolved into(Bi_0.5Na_0.5)(Ti_0.95Al_0.025Nb_0.025)O₃to form（1-x）BNTA-x SSN ceramics.It is a standard perovskite ceramic,and each component has a pseudocubic structure.According to the analysis of dielectric temperature spectrum test results,the temperature T_mcorresponding to the maximum dielectric constant of（1-x）BNTA-x SSN ceramics moves to the direction of low temperature with the increase of SSN content,and the dielectric constant peak widens and the dispersion degree increases,indicating that the relaxation of（1-x）BNTA-x SSN ceramics is enhanced.The maximum effective energy storage density(W_rec)of 0.90BNTA-0.10SSN ceramics was 2.7J/cm~3when x=10mol%.When x=15mol%,the maximum energy storage efficiency（η）of 0.85BNTA-0.15SSN ceramics is 85%.Temperature and frequency stability tests show that 0.90BNTA-0.10SSN ceramics have excellent temperature and frequency stability.The influence of temperature change on energy storage performance is less than 1.4%in the range of 40℃to 120℃,and the influence of frequency on energy storage performance is less than 4%in the range of 5Hz-400Hz.The lead-free ceramic system（1-x）(K_0.5Na_0.5NbO₃)-x(Bi Mg_0.5Ti_0.5O₃)(abbreviated as（1-x）KNN-x BMT,was constructed by solid solution of Bi Mg_0.5Ti_0.5O₃and K_0.5Na_0.5NbO₃,x=0mol%,5mol%,10mol%,15mol%).（1-x）KNN-x BMT ceramics were successfully prepared by traditional solid state reaction method,and the effects of solution of Bi Mg_0.5Ti_0.5O₃on the grain structure,phase structure,energy storage properties,dielectric properties and optical properties of KNN matrix ceramics were systematically studied.XRD analysis of（1-x）KNN-x BMT ceramic powders at the optimum sintering temperature showed that Bi Mg_0.5Ti_0.5O₃dissolved well into K_0.5Na_0.5NbO₃and formed a single solid solution with pseudo-cubic structure.The results of dielectric temperature spectrum test show that T_mmoves towards low temperature with the increase of BMT content,the dielectric constant peak widens gradually,and the dispersion factor increases,indicating that the relaxation characteristics of ceramic after solid solution are enhanced.When x=10mol%,0.90KNN-0.10BMT ceramics have the maximum effective energy storage density(W_rec)of 2.65J/cm~3.When x=20mol%,0.80KNN-0.20BMT ceramics have the maximum energy storage efficiency（η）of 84%.The transmittance of（1-x）KNN-x BMT（x=5mol%,10mol%,15mol%）ceramics has excellent transmittance.The transmittance in visible light range is over 60%.Lead-free ceramic system（1-x）(K_0.5Na_0.5NbO₃)-x(SrBi_0.5Nb_0.5O₃)（abbreviated as（1-x）KNN-x SBN）was constructed by solid solution of SrBi_0.5Nb_0.5O₃and K_0.5Na_0.5NbO₃,x=5mol%,10mol%,15mol%,20mol%).The influence of SrBi_0.5Nb_0.5O₃on the properties of KNN based ceramics was studied by traditional solid state reaction method.XRD refinement and Raman spectrum analysis show that SrBi_0.5Nb_0.5O₃is successfully dissolved into K_0.5Na_0.5NbO₃,forming a single solid solution.When x>5mol%,the phase structure changes from orthogonal phase to pseudo-cubic phase.The test of dielectric temperature spectrum shows that T_mmoves towards low temperature with the increase of SBN content,the peak of dielectric constant widens,the degree of dispersion increases,and the relaxation property of ceramics increases.When x=10mol%,0.90KNN-0.10SBN ceramics have the maximum effective energy storage density(W_rec)of 1.75J/cm~3.When x=20mol%,0.80KNN-0.20SBN ceramics have the maximum energy storage efficiency（η）of 87.6%.The charge-discharge test results show that0.80KNN-0.20SBN ceramics complete the charge-discharge process within 1.51μs.