Preparation,Structure,Dielectric And Energy Storage Properties Of BaTiO₃-BiMeO₃ Based Relaxor Ferroelectrics

As the excellent energy storage devices,the dielectric capacitors have been widely used in electric vehicles,high frequency converters and other pulse power systems.Compared with batteries,fuel cells,and supercapacitors,dielectric capacitors typically have high power density,fast charge/discharge rates,and long cycle lifetimes.With the rapid development of electronic components for miniaturization,low cost and safety,much requirements are put forward to the energy storage properties of dielectric capacitors.In order to meet these requirements,this paper focuses on the development of high dielectric constant and environmentally friendly BaTiO₃ ceramic capacitor and regulates the dielectric and the energy storage characteristics of BaTiO₃ via doping other perovskite compounds.In this paper,all materials were prepared by the traditional state reaction methods.(Ba_1-xBi₀.67xNa_0.33x)(Ti₁-xBi_0.33xSn_0.67x)O₃（BBNTBS）ceramic capacitors were prepared based on the high dielectric constant and wide temperature stability.A series of ceramic materials including（1-x）BaTiO₃-xBi(Ni_0.5Zr_0.5)O₃（BT-BNZ）,（1-x）BaTiO₃-x Bi(Mg_2/3Ta_1/3)O₃（BT-BMT）,0.88BaTiO₃-0.12Bi(Li_1/3Zr_2/3)O₃（0.88BT-0.12BLZ）,0.9BaTiO₃-0.1Bi(Li_1/3Zr_2/3)O₃（CBNT0）and 0.9[0.9(Ba_0.8Ca_0.2)TiO₃-0.1Bi(Li_1/3Zr_2/3)O₃]-0.1Bi_0.5Na_0.5TiO₃（CBNT1）ceramics were synthesized based on the energy storage properties.Furthermore,the phase structure,dielectric properties and energy storage properties of the above materials were systematically studied.The main conclusions are summarized as follows:（1）By introducing(Bi³⁺,Na⁺,Sn⁴⁺)ions into BaTiO₃ matrix,serials of high dielectric ceramic materials were developed to meets the requirements of EIA X8R MLCC.The excellent dielectric properties show great advantages in BaTiO₃-based ceramic systems and are expected to be a candidate material for the new EIA X8R MLCC.（2）Based on BaTiO₃ matrix,a novel serials of high performance BaTiO₃ based relaxor ferroelectrics energy storage dielectric materials（BaTiO₃-BiMeO₃）were designed and synthesized.By introducing BiMeO₃,the disorders of A-site and B-site ions for BaTiO₃ matrix are formed,which destroys the order of ferroelectric long-range and transforms ferroelectric domains into polar nanoscale regions（PNRs）.The energy storage density and energy storage efficiency of BaTiO₃ ferroelectric ceramics could be significantly improved by the rapid response of PNRs under the applied electric field.Meanwhile,it is revealed that the excellent energy storage characteristics of BaTiO₃-BiMeO₃ relaxor ferroelectric ceramic system may be attributed to its weakly coupled relaxor ferroelectrics behavior.Finally,ultrahigh energy storage density（≥3J/cm³）and energy storage efficiency（≥90%）were simultaneously achieved in 0.88BT-0.12BMT and 0.88BT-BLZ ceramics.（3）By introducing Ca²⁺and Bi₀.5Na0.5TiO₃,constructing local compositional disorder and decreasing grain size,the polarization strength and breakdown strength of BaTiO₃-BiMeO₃ relaxed ferroelectric ceramics were significantly optimized simultaneously to obtain an ultrahigh energy storage density（4.223 J/cm³）and energy storage efficiency（93.4%）.Meanwhile,the energy storage density of the component shows decent temperature and frequency stability,and has the feasibility of working at a relatively high temperature（190^oC）.In addition,the relationship between composition-structure-property as well as the origin of the decent energy storage properties was studied.This may provide guidance for the subsequent development of BaTiO₃-BiMeO₃ based ceramic materials with high energy storage characteristics.