The Energy Storage Properties And The Electrocaloric Effect Properties Of Lead Zirconate Titanate Based Antiferroelectric Ceramics

With the rapid development of science and technology,anti-ferroelectric materials have become one of the hot topics in international research.The modified PbZrO₃ antiferroelectric material changes from ferroelectric phase to antiferroelectric phase under electric field,which produces considerable strain,and can be used to make micromechanical electronic devices such as sensors and actuators.In addition,this kind of material can be used in high energy storage devices,dielectric tuning devices and so on.In this paper,the properties of antiferroelectric materials are introduced by various characterization methods,which has mostly include four sections as follow:First,(Pb_1-3x/2La_x)(Zr_0.95Ti_0.05)O₃?x=0.02,0.04,0.06,0.08,0.10?ceramics were successfully synthesized by a solid state mixed oxide technique.Dielectric properties and impedance were tested at a temperature of 26-650 ^oC with frequency and temperature as relevant quantities.In the dielectric study of ceramics,the peak of phase change can be observed in the range of phase change temperature,while the Curie temperature of the sample decreases with the increase of lanthanum content.The phase transition process was observed in hysteresis lines.With the increase of lanthanum content,the temperature range of phase transition decreased.In the high temperature region,the relation between high temperature dielectric relaxation and oxygen vacancy and the activation energy of high temperature dielectric relaxation are studied.According to Arrhenius law,activation energy value between 0.43-1.61 eV,conductivity activation energy values 0.38-1.66 eV between,which indicates that the conductivity mechanism is a thermal process.At the same time,this value of activation energy indicates that the relaxation mechanism of the material is controlled by dipole conduction.The dynamic thermal motion of the ionized oxygen vacancy can explain this behavior.Second,throughhigh-temperaturesolidphasereactionpreparation of(Pb_0.97La_0.02)(Zr_0.95Ti_0.05)O₃ ceramics,the dielectric and ferroelectric were analyzed in a certain temperature range.The ceramic samples showed good ferroelectric properties and energy storage characteristics,which were investigated in this work with an emphasis on energy storage properties.The maximum effective energy storage density of ceramics was0.83 J/cm³ and the corresponding efficiency was 70%.In addition,the ceramic samples showed a large electrocaloric effect value.The adiabatic temperature change was-7.47 K when the electric field was 50 kV/cm,which could be great potential in achieving large power as refrigerants.(Pb_0.97La_0.02)(Zr_0.95Ti_0.05)O₃ ceramics have many excellent properties and can be used in many fields,providing us with a wide exploration space.Third,(Pb_0.97?1+x?La_0.02)(Zr_0.95Ti_0.05)O₃?x=0,3%,5%,7.5%,10%and 15%?ceramics were successfully synthesized by a solid state mixed oxide technique with different excess lead content.X-ray diffraction analysis indicated that a pure perovskite structure was obtained for all compositions.The dielectric properties of ceramics were systematically investigated,which exhibited tetragonal phase structure and showed two dielectric peaks at120 and 240 ^oC,corresponding to ferroelectric-antiferroelectric and ferroelectric-paraelectric phase transitions.The ferroelectric properties of samples were good.The recoverable energy-storage density calculated from hysteresis loops reached about 2.12 J/cm³ and efficiency of 92.98%.Based on these results,the typical ceramics with different lead excess content had been studied,which could be a potential candidate for the applications in high energy storage-density electrical capacitors.Finally,Sn-doped(Pb_0.97La_0.02)(Zr_0.95Ti_0.05)O₃ ceramics were prepared by by a solid state mixed oxide method.The dielectric properties of ceramics were systematically investigated and the dielectric constant decreased significantly with the increase of Sn⁴⁺.The phase transition temperature?T_o?moves to the direction of low temperature,the sharp peak?T_C?gradually becomes a broad peak.The energy storage density of the sample was 0.954J/cm³,and the corresponding energy storage efficiency was 62.72%.Sn-doped lead zirconate titanate based antiferroelectric ceramics are a promising dielectric high energy storage capacitor material.