Microstructure and properties of KNN-based transparent ceramics doping the nanocomposite sintering aids
Purposes—To investigate the structure and properties of transparent KNN-based ceram-ics doped with the nanocomposite sintering aids.Methods—Zn-B-Si-O(ZBS)nanocomposite sintering aid was prepared with sol-gel method and ZBS nanocomposite doped with KNN lead-free piezoelectric ceramics were prepared with solid-state method.The effect of doping amount of nanocomposite sinte-ring aids on the density,microstructure,phase structure and properties of transparent KNN ceramics was studied.Results—The calcination temperature of ZBS nanocomposite sintering aids prepared with sol-gel method is 400 ℃,and the particle size of ZBS nanocomposite powder which is prepared when the pH of sol is 2 is the smallest(30 nm),and it is evenly dispersed.The optimal sintering tempera-ture for KNN-0.03CZN ceramics when nano ZBS sintering aid isn t doped with is 1 140 ℃(4.50 g/cm3).When the nano ZBS sintering aid x=1.50 wt%,the optimal sintering temperature for KNN-0.03CZN ceramics is 900 ℃(4.57 g/cm3).It is evident that as the doping amount of nano ZBS sinte-ring aid increases,the optimal sintering temperature decreases by 220℃.The ceramic grains are reg-ular cubic and is characterized by uniform grain size,fewer intergranular pores and better density.KNN-0.03CZN-1.00ZBS exhibited high density(98%),high transmittance(34.02%and 39.33%)in the visible light range and near-IR region and respectively good electrical properties(εr=2 518,tanδ=0.02,Pr=6.88 pC/cm2,Ec=8.49 kV/cm).Conclusions—The use of nano sintering aids can bet-ter promote ceramic sintering and increase the density of ceramics and transmittance of transparent ceramics.