Preparation,characterization And Properties Of BaTiO₃-based Composite Ceramic Materials

With the rapid development of electronic technology,electronic products continue to miniaturization,portability,automation,networking,large capacity,multi-functional,low loss and environment-friendly development.In recent years,it has attracted considerable attention as a basic electronics ceramic capacitor.Scientific researchers develop high-performance dielectric material is imminent.In all kinds of dielectric materials,lead-free ferroelectric material BaTiO₃ with its excellent performance and modification becomes the preferred object of many researchers.Na_0.5Bi_0.5TiO₃?NBT?,as one of the most promising lead-free materials,has attracted continuous attention.It has relatively high Curie temperature,low sintering temperature and strong ferroelectric,is one of the most studied lead-free materials.In this paper considering the modification by using the method of doping and two phase composite,preparation with high dielectric ceramic materials of high stability and low loss.Given the current demand for ceramic material stability,ions-doping BaTiO₃ and incorporating the NBT,has been prepared successfully by the solid state reaction method.For NBT ceramic powders,analyzes and discusses the different ingredients ratio and milling time effect on XRD and morphology.The preparation of NBT conditions have been determined as follows: Na:Bi=_0.55:0.45,(Na_0.5Bi_0.5):Ti=1.15:1,the grinding time for 1h,presintering temperature is 800 °C,holding time of 1 h.New dielectric composite ceramics of Na_0.5Bi_0.5TiO₃-Ba_1-xSr_xTi_0.995Zr_0.005O₃?NBT-BSTZ??x=0.05,0.1,0.2,0.3?have been fabricated by the wet solid-state route.The effect of Sr content on phase structure and electrical properties has been investigated in detail.With increasing Sr content,the ceramic capacitors display larger dielectric constant,better temperature stability and lower dielectric loss in its dielectric behavior.The ceramics with composition x=0.3 possess a large dielectric constant??r?of 2522.The temperature coefficient of capacitance of NBT-BSTZ varies from-39% to 36% in the temperature range between 0°C and 200°C.The dielectric loss of capacitance is below 0.07 while the Sr content is 0.3 at the whole range of measured temperature.The results indicate that Sr-doping is an effective method to modulate the temperature stability and dielectric loss of the NBT-BSTZ dielectric ceramics.The ceramics with the composition of xNa_0.5Bi_0.5TiO₃-?1-x?Ba_0.66Mg_0.04Sr_0.3TiO₃?NBT-BMST?in which x=0.2,0.3,0.4,0.5 were prepared successfully by the solid state reaction method.The effects of NBT/BMST ratio on phase structure,morphology,temperature stability and dielectric properties had been investigated in detail.The dielectric constant of 0.3Na_0.5Bi_0.5TiO₃-0.7Ba_0.66Mg_0.04Sr_0.3TiO₃ ceramic is ⁴100,the temperature coefficient of capacity is-15%,15%,and 22% at-55°C,60°C,and 200°C,respectively.And the dielectric loss is less than 0.13,which is obviously superior to other compositions.According to the characteristics of rare earth elements can significantly improve the dielectric properties of BaTiO₃,select the Sr,Sn as quantitative elements together with La doping NBT-BT,discusses the multiple elements codoping impact on performance.A broad working temperature dielectric material,Na_0.5Bi_0.5TiO₃-Ba0.7-1.5xLaxSr_0.3Sn_0.1Ti0.9O₃?NBT-BLSST?has been prepared successfully by the solid state reaction method.The effects of La-doping on phase structure,morphology,temperature stability and dielectric properties have been investigated in detail.The dielectric constant of sample ball-milled by zirconia balls for _0.5h in the mixer can reach 4618 while the La doping is 0.8 mol%.The dielectric loss of capacitance is below 0.097.The temperature coefficient of capacitance varies from-15.02% to 16.13% in the temperature range between-55°C and 200°C.It is particularly worth mentioning the temperature coefficient of capacity varies from-15.02% to 14.46% at the temperature range between-45°C and 200°C.The temperature characteristic of capacitance is very close to EIA X9 R specifications.