| In recent years,with the wide application of power pulse technology in industry,military and civil fields and the vigorous development in electric power vehicle industry,the demand for dielectric capacitor is increasing rapidly,so finding a new environment-friendly dielectric ceramics with high energy storage has become a hot issue for researchers.In this paper,sodium bismuth titanate based ceramic material was selected as the basic material,with the introduction of new dopants,the changes of phase structure and electrical properties were explored systematic,which reveals the influence of ceramic's phase structure on its properties.This work is committed to develop a new kind of ceramic materials with high energy storage performance and energy storage efficiency.The main conclusions of this study are as follows:A series compositions of(1-y)(Na1-xKx)0.5Bi0.5TiO3-yBaTiO3 are chosen around the morphotropic phase boundary region of BNT-BKT-BT ternary system,and were successfully prepared by conventional solid-state reaction method in 1150?.By analysis the sample's X-ray diffraction pattern and Raman spectroscopy,the results showing the coexisting of rhombohedral and tetragonal.It can be seen that the content of tetragonal phase gradually increased with the increase content of BKT and BT.By test the ceramics'dielectric and ferroelectric properties,the components located in the MPB area have better dielectric and ferroelectric properties.The composition(x=0.18,y=0.06)of all components in this study has the best electrical properties:?r=3557,tan?=0.06.The ceramic components around MPB area have better relaxation characteristics,the hysteresis line is thinner,and the discharge energy storage density is also higher.Of all the components,the component of the x=0.22,y=0.06 has the best energy storage performance,Wrec=0.42J/cm3 and the energy storage efficiency is 27.8%.The effects of BiMeO3 on the phase structure,microscopic morphology,electrical properties and energy storage performance of BNKT-based ceramics were studied systematically.The results show that the main crystalline phase of ceramics are perovskite structure,Me ion groups with larger ionic radius than titanium ions such as(Zn2/3Nb1/3)3+and(Mg2/3Nb1/3)3+,are introduced into ceramics,which would distort the lattice.The test results of X-ray diffraction pattern and Raman spectroscopy shows that with the increase of Me ion groups content,the phase structure of ceramics is transformed from rhombohedral to tetragonal.It makes the dielectric constant of ceramics decrease,and the dielectric peak is also constantly widened.(1-x)BNKT-xBZN ceramics have excellent energy storage performance,the hysteresis presents a thin shape,for the components of x=0.08,the breakdown strength of ceramics can reach 110kv/cm,the difference between maximum polarization strength and residual polarization strength is ?P=26.3?C/cm2.The effective energy storage of ceramics is Wrec=1.10J/cm3,while total energy storage is 1.97J/cm3,the energy storage efficiency can reach ?=55.9%(1-x)BNKT-xBMN ceramics presents better energy storage property,for the components of x=0.08,the breakdown strength of ceramics can reach 110kv/cm,the difference between maximum polarization strength and residual polarization strength ?P is 28.8?C/cm2,while its total energy storage is 2.21 J/cm3,The effective energy storage of ceramics is Wrec=1.23/cm3,and the energy storage efficiency can reach ?=55.6%. |
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