| In recent years,with the application of ceramic capacitors in the fields of new energy vehicles,high-power power electronics,underground resource exploration and aerospace industry,requiring a higher temperature range(?300?),traditional ceramic capacitors have been unable to meet Its use requirements.The Curie temperature of Bi0.5Na0.5TiO3(BNT)-based relaxation ferroelectrics is high(?540?),which shows a double-dielectric peak structure in the dielectric temperature spectrum.By adjusting its composition,it is hoped that the relative A good temperature stability of dielectric properties is obtained in a wide temperature range.In addition,it also has a high polarization intensity(?40 ?C/cm2),and a double-hysteresis loop similar to antiferroelectricity can be obtained by component control.Therefore,whether it is a temperature-stable capacitor or an energy storage capacitor,BNT-based materials are very promising materials.In this paper,BNT ceramic is used as the matrix.Through the composition control,a dielectric material with good temperature stability and low dielectric loss in a wide temperature range is obtained.Causes of temperature stability of dielectric properties.The main content of the paper includes the following aspects:(1)Bi0.5Na0.5TiO3-100xBiAlO3 ceramics were prepared by solid state reaction.The phase structure and electrical properties of the ceramics were studied.The dielectric temperature spectrum shows that with the increase of BiAlO3 content,the loss is lower and lower,and the defect dipoles(AlTi'-Vo"-AlTi')suppress the oxygen vacancy,thus reducing the dielectric loss.At 1 kHz and 300?,the loss of BNT-06BA decreased from 0.24857 of pure BNT to 0.01278.Impedance analysis showed that the addition of BiAlO3 reduced the conductivity of BNT,and the inhibition of oxygen ion conductivity significantly reduced the dielectric loss at high temperature.(2)The ternary system of Bi0.5Na0.5TiO3-100xBiAlO3-100yCaZrO3 ceramics was prepared.The effects of the doping of BiAlO3 and CaZrO3 on the structure and electrical properties of the materials were studied.XRD results show that all the samples have a single perovskite structure,and the second phase appears when the doping amount is 10%BiAlO3.The increase of CaZrO3 content is beneficial to the formation of inhomogeneous domain structure and the temperature stability of dielectric constant.BNT-9BA-5CZ has good overall dielectric properties.The change rate of dielectric constant is ??'/?'200?<±15%,the temperature range is 133?-500?,and the temperature range of dielectric loss tan??0.02 is 160??425?.(3)The samples of Bi0.5Na0.5TiO3-BiAlO3-100xSrTiO3 ceramics were prepared by solid-phase sintering.The XRD results show that all the samples are of single perovskite structure and have no heterophase.It can be seen from SEM that the grain size is smaller and smaller with the increase of SrTiO3 content.The dielectric temperature spectrum shows that the component of BNT-9BA-15ST has excellent dielectric properties.The change rate of dielectric constant??'/?'200?<±15%is 96.7?-396.8?,and the temperature range of dielectric loss tan??0.02 is 132.8??391.8?.More importantly,it has a high dielectric constant(1 kHz,3108)while maintaining a wide temperature range,which indicates that the addition of SrTiO3 can improve the temperature stability of the dielectric properties of BNT-BA based ceramics.(4)Bi0.5Na0.5TiO3-100xBiAlO3-100yNaNbO3 ceramic samples were prepared by solid-phase sintering.The dielectric properties,conductivity and energy storage properties were studied.XRD results show that all the samples are single perovskite structure.The dielectric thermogram shows that the addition of NaNbO3 can effectively reduce the non ergodic phase in bnt-ba and make the sample become a main ergodic relaxation body.In the temperature range of-90??320?,not only stable dielectric constant ??'/?'25?<±15%,but also low dielectric loss tan??0.02 can be achieved.In addition,it has a high RC constant of 2.8 s,the energy storage density of BNT-10BA-30NN is 0.17 J/cm3,and the energy storage efficiency of 60 kV/cm electric field at room temperature is 88%. |
PDF Full Text Request