Structural Control And Photoelectric Properties Of Rare Earth Doped KNN-Sr(Bi_0.5M_0.5)O₃（M=Nb,Ta） Fluorescent Transparent Ferroelectric Ceramics

In this work,the second component Sr(Bi_0.5M_0.5)O₃（M=Ta,Nb）is dissolved in solid solution based on(K_0.5Na_0.5)NbO₃（KNN）by the traditional solid-phase method.By adjusting the different components of the second component,lead-free transparent ferroelectric ceramics with excellent light transmission properties were prepared.On this basis,the component points with better light transmittance properties were selected and further doped with rare earth elements Ho,Yb and Er,respectively,and ceramic samples with good up-conversion luminescence properties while maintaining excellent light transmittance were successfully prepared.An excellent multifunctional material.At the same time,the effects of rare earth element doping on the optical,electrical,phase structure and microstructure of ceramic samples were systematically studied.The specific research contents are as follows:（1）（1-x）(K_0.5Na_0.5)NbO₃-x Sr(Bi_0.5Ta_0.5)O₃（x=0.018,0.02,0.022,0.024,0.026,0.028）ceramics were designed and prepared.The effects of solid solution of Sr(Bi_0.5Ta_0.5)O₃（SBT）with different contents on the light transmittance,phase structur e,microstructure and ferroelectric and energy storage properties of ceramic sam ples were investigated.The research shows that with the increase of the solid solution content of SBT,the transmittance of the ceramic sample shows a tren d of first increasing and then decreasing.It reaches 60.28%,and reaches 72.14%in the near-infrared band（1100nm）;the phase structure of the ceramic sample gradually changes from tetragonal to pseudo-cubic phase with the increase of t he second component SBT content;The grain size increases and then decrease s;the electrical properties of the ceramic samples gradually decrease with the i ncrease of the solid solution content of SBT.（2）（1-x）(K_0.5Na_0.5)NbO₃-x Sr(Bi_0.5Nb_0.5)NbO₃（x=0.02,0.03,0.04,0.05,0.06,0.07）ceramics were designed and prepared.The effects of different Sr(Bi_0.5Nb_0.5)O₃（S BN）contents in solid solution on the transmittance,microstructure,phase struct ure and electrical properties of ceramic samples were investigated.The study s hows that the second component SBN is completely integrated into the KNN u nit cell,forming a pure perovskite structure without the formation of the secon d phase.When the SBN solid solution content is x=0.06,the transmittance of the ceramic sample reaches the highest,the transmittance in the visible light ba nd（780nm）reaches 64.64%,and the transmittance in the near-infrared band re aches（71.68）.The grain size of the ceramic samples increased first and then d ecreased with the increase of the solid solution content of SBN.With the incre ase of the solid solution amount of SBN,the electrical properties of the ceram ic samples gradually weakened,the remanent polarization decreased from 24.5μC/cm² to 8.7μC/cm²,and the recoverable energy storage density decreased from1.05J/cm³ to 0.54J/cm³（3）0.94(K_0.5Na_0.5)NbO₃-0.06Sr(Bi_0.5Nb_0.5)O₃:x wt%Er³⁺（x=0.1～0.4）cerami cs were designed and prepared.The effects of Er³⁺doping on the optical prop erties,electrical properties,phase structure and microstructure of ceramic sampl es were systematically studied.The results show that the ceramic samples are i n the pseudo cubic phase structure with the weakest optical anisotropy.The tra nsmittance of ceramic samples is more than 70%in the visible band（780nm）,and the highest transmittance is 80.25%in the near-infrared band.With the inc rease of Er³⁺doping content,the up conversion luminescence intensity of cera mic samples gradually increases and then decreases.When Er³⁺doping content x=0.03wt%,the fluorescence peak intensity of the emission spectrum of cerami c samples reaches the highest.Through the scanning electron microscope test,i t can be seen that the grain size of the ceramic sample has reached the nano level and has a dense microstructure.The results show that a multifunctional material with excellent light transmittance and up conversion luminescence prop erties has been successfully prepared.（4）0.94(K_0.5Na_0.5)NbO₃-0.06Sr(Bi_0.5Nb_0.5)O₃:0.1wt%Ho³⁺/xwt%Yb³⁺（x=0.5,1,1.5,2）ceramics were designed and prepared.The effects of different dopi ng contents of Yb³⁺as luminescent sensitizer on the optical properties,electrica l properties,phase structure and microstructure of ceramic samples were system atically studied.The results show that Yb³⁺can significantly enhance the upcon version luminescence intensity of Ho³⁺as the luminescence center.There are t wo strong fluorescence peaks at 550nm and 650nm,and the upconversion lumi nescence intensity will be further enhanced with the increase of Yb³⁺doping c ontent.XRD results show that the sample has pure perovskite structure and no miscellaneous formation.The transmittance of ceramic samples decreases gradua lly with the increase of Yb³⁺doping content.With the increase of Yb³⁺doping content,the grain size of ceramic samples gradually becomes larger and its d ensity gradually decreases...