Study On Dielectric Properties Of Telluride Glass Doped CaCu₃Ti₄O₁₂ Ceramic

CaCu₃Ti₄O₁₂（CCTO）ceramic has attracted great attention because of their high dielectric constant,excellent frequency and temperature stability,which has great potential role in miniaturized electronic devices.However,high dielectric loss and sensitive process stability limit the application of CCTO ceramic in electronic components.In this paper,CCTO ceramic was prepared by solid-state reaction using CaCO₃,CuO and TiO₂ as raw materials,and tellurite glass was prepared by melting annealing at high temperature using CaCO₃,TeO₂,H₃BO₃,ZnO,SrCO₃ and BaCO₃ as raw materials.By means of XRD,FESEM,EDS,FI-IR and dielectric properties test,the effects of CCTO powder synthesis（calcination temperature and holding time）on phase composition,microstructure and dielectric properties of CCTO ceramic were studied;the composition,structure and properties of tellurite glass were studied;and the effects of the content of tellurite glass doped CCTO ceramic and sintering process on phase composition,microstructure and dielectric properties were investigated.The results show that the synthesis temperature has a great influence on the purity,grain size and crystallinity of CCTO powders,while the influence of synthesis time is smaller.The optimum conditions for the synthesis of high purity CCTO powder are calcined at 950-1030°C for 2 h.The synthesis process of CCTO powder has an effect on the microstructure and dielectric properties of the ceramic.The synthesis temperature has a great influence on the crystallinity of CCTO powders,while the influence of the synthesis time is relatively small.The process is calcined at 950 C for 12 hours.The dielectric loss of 55TeO₂-21B₂O₃-10ZnO-4CaO-5SrO-5BaO system glass is lower.At 10kHz,the dielectric loss is 0.0046 and the dielectric constant is 11.15.With increase of ZnO content,the decrease of TeO₂ content,the[TeO₄]group in tellurite glass decreases,the[TeO₃]group increases,the dielectric constant increases,and the dielectric loss first decreases and then increases.When the content of CaO increasing from 4mol%to 8mol%,the content of TeO₂ decreasing from 61 mol%to 57 mol%,the[TeO₄]group of tellurite glass decreases,the[TeO₃]group increases,the dielectric constant loss increases.With the content of B₂O₃ increases,the corresponding TeO₂ decreases,the[TeO₄]group and[BO₃]group of tellurite glass decreases,the[TeO₃]group and[BO₄]group of tellurite glass increase,and the dielectric constant loss decreases.The optimum preparation conditions of coarse-grained CCTO powders are 1080°C calcination for 2 hours.The tellurite glass as additive promotes the sintering of CCTO ceramic,the density of ceramic increases,the grain size increases,and the dielectric loss decreases.The optimum content of tellurite glass is 20 vol%,and the dielectric constant of CCTO ceramic is 11343 and the dielectric loss is 0.063（10 kHz at room temperature）.Tellurite glass doping can effectively reduce the sintering temperature and time of CCTO ceramic.The optimum sintering condition is 1030°C for 2 hours.