Preparation And Energy Storage Performance Of Bismuth Sodium Titanate Based Wide Temperature Multilayer Ceramic Capacitor

BNT-based dielectric ceramics is a lead-free perovskite material with high potential application value.In this paper,a new type of BNT-based energy storage dielectric ceramics with high temperature stability was prepared to meet the increasing demand of practical application.Sodium bismuth titanate-barium zirconate titanate（BNT-BZT）was selected as the research object.By adjusting the solid solution of BZT（x）,the ratio of Zr⁴⁺/Ti⁴⁺in BZT（y）and doping Sm³⁺（z）,BZT-BNT ceramics had obtained good temperature stability.Finally,the obtained ceramic component was tape casted and stacked to obtain multilayer ceramic capacitors.The main contents are as follows:A series of（1-x）Bi_0.51Na_0.47Ti O₃-x Ba Zr_yTi_1-yO₃ceramic samples with different x and y values were prepared.High temperature stability and single proveskite phase were obtained in 0.50Bi_0.51Na_0.47Ti O₃-0.50Ba Zr_0.45Ti_0.55O₃ceramic（abbreviated as50-45 ceramic）.At the optimum sintering temperature,the bulk density of 50-45ceramic was as high as 5.96 g/cm³.The dielectric test showed that the Curie temperature of 50-45 component ceramic was reduced to room temperature due to the change of x and y values,and the dielectric peak near T_dwas reduced,so that the range of TCC_25°C≤15%reached to-26～280°C.The energy density was W_rec=1.75J/cm³,which accompanied with high energy storage efficiencyη=83.7%.The rare earth element Sm was selected to further stabilize the properties of50-45 ceramic.The experimental results showed that Sm³⁺ions successfully entered the lattice.The temperature stability of BNT-BZT-0.04Sm ceramic was improved withΔεreducing to less than 15%,showing excellent dielectric stability.BNT-BZT-0.04Sm ceramic obtained W_rec=1.12 J/cm³andη=89.6%.The energy storage performances tested from room temperature to 200°C displayed the good temperature stability in BNT-BZT-0.04Sm ceramic.There was no obvious change in the shape of P-E curve in the test temperature range,and the change rate of energy storage performance in the range was less than 5%.The charge-discharge test showed that under the electric field of 140 k V/cm,the BNT-BZT-0.04Sm ceramic obtained a very fast discharge speed with t_0.9=0.655μs,which indicated that the BNT-BZT-0.04Sm ceramic also had excellent discharge performance.The BNT-BZT-0.04Sm bulk ceramic was prepared into multilayer ceramic capacitors.The temperature range of removal of organic matter process was found out to be 230～450°C,and the residual organic matter volatilizes at 450～600°C,which can appropriately increase the heating rate.The size of the whole green body was reduced by about 25%,which showed that the MLCC became dense in the process of heating.The dielectric and P-E tests and of MLCC showed the excellent temperature stability and energy storage performance:the change rate of dielectric constant wasΔε≤11%in the test temperature range of-60～200°C,and a high W_recof 2.08 J/cm³andη=84.2%were obtained at a breakdown strength of 220 kV/cm.