Doping Modification And Absorbing Properties Of SrTiO₃ Ceramics

With rapid development of science and technology,the microwave absorption materials have been paid more and more attention in the field of weapons and equipment.Although traditional absorbing materials,such as ferrite,carbon-containing materials,metal powder and so on,have the advantages of absorption bandwidth and strong absorption ability,the disadvantages of poor oxidation resistance and large thickness limit their long use in high temperature environment.Therefore,it is imperative to study new absorbing materials with small thickness and oxidation resistance.SrTiO₃ceramic is widely applied in the field of electronic applications due to its typical ABO₃perovskite structure,high dielectric constant,excellent temperature stability and other advantages.Besides,previous studies have shown that its dielectric properties can be adjusted by doping with rare earth element to replace A or B ions,which is beneficial to improve its impedance matching performance.Therefore,30%Al₂O₃-Sr_1-xRe_xTiO₃ceramics were designed and fabricated by vacuum hot-pressing sintering technology in this study.The effect of doping rare earth elements and doping content on the phase composition,microstructure,element distribution,electrical conductivity,electromagnetic property and absorbing properties of 30%Al₂O₃-Sr_1-xRe_xTiO₃ceramics in X band?8.2-12.4 GHz?were further systematically studied.The main work and conclusions of this paper are presented as follows.The Sr_1-xEr_xTiO₃precursor was prepared by solid-state reaction and subsequently sintered by hot pressing after adding Al₂O₃ceramic matrix to produce 30%Al₂O₃-Sr_1-xEr_xTiO₃ceramic samples with high density.The effect of Er³⁺ion doping content on ceramic properties was studied systematically.When the doping content is 0.1,the ceramic has a certain absorbing capacity.When the thickness of the ceramic is 0.412 mm,the absorption band width?reflection loss<-5 d B?is 4.1 GHz?8.2-12.3 GHz?,which indicates that it has the potential to become a candidate of absorbing material.The A site of SrTiO₃was partly replaced by doping modification.The effect of doping content of Ce³⁺ions on the absorbing properties and other properties of 30%Al₂O₃-Sr_1-xRe_xTiO₃ceramics was studied.The density of these ceramics after hot-pressing sintering is very high.According to the analysis of element distribution combined with XRD patterns,the Ce³⁺ions successfully entered the interior of the SrTiO₃crystal.When the doping content is 0.2,the bandwidth?reflection loss<-10 d B?is 1.4 GHz?11.0-12.4 GHz?with a thickness of 0.84 mm,indicating the ceramic has a good absorbing performance.The influence of doping content of Gd³⁺ions on the dielectric parameters and absorbing properties of 30%Al₂O₃-Sr_1-xRe_xTiO₃ceramics was studied.Based on the analysis of energy spectrum and component,the results show that Gd³⁺ions successfully entered the interior of the SrTiO₃crystal.With the increase of doping content,the conductivity increases firstly and then decreases.When the Gd³⁺doping content is 0.1,the lowest reflection loss value is-49.7 d B at10.59 GHz with a thickness of 0.336 mm.When the Gd³⁺doping content is 0.2,the absorbing bandwidth?reflection loss<-10 d B?is 4.2 GHz,covering the whole X-band?8.2-12.4 GHz?with a thickness of only 0.341 mm.The above results reveal that 30%Al₂O₃-Sr_1-xGd_xTiO₃ceramic has an excellent microwave absorption property and can be used as a promising candidate for designing absorbing materials.