CaTiO_(3)-Sm_(0.9)Nd_(0.1)AlO_(3) ceramics with a moderate dielectric constant and a high quality factor prepared by sol-gel auto combustion method

CaTiO_(3)-LnAlO_(3)(Ln=La,Nd,Sm) is a perovskite-type microwave material system characterized by a moderate dielectric constant εr,a high quality factor Q×f,and a small temperature coefficient of resonant frequency τf,making this system promising for microwave devices.However,its high synthesis temperature and sintering temperature limit its industrial applications.In our work,single phase0.7 CaTiO_(3)-0.3 Sm_(0.9)Nd_(0.1)AlO_(3)(7 CT-3 SNA) was synthesized via the sol-gel auto combustion method using citric acid as fuel at a relatively low temperature.After being calcined at 600℃ for 2 h,wellcrystallized 7 CT-3 SNA powders with 30-50 nm average particle size were achieved,suggesting good sintering activity.The new and narrow order band at about 800 cm^(-1) in the Raman spectra indicates a high ordering degree in the B site of 7 CT-3 SNA solid solution.Compared with the solid-state reaction method and co-precipitation method,the 0.7 CT-0.3 SNA ceramics fabricated by the current method possess a much lower calcination temperature,a similar εr value,and an improved Q × f value.The optimum microwave dielectric properties of εr=43.54,Q×f=54375 GHz,and τf=-6.3 ×10^(-6)/℃ are obtained for the CTSA ceramics derived from the sol-gel auto combustion process.Therefore,the 7 CT-3 SNA ceramics prepared in this study are potential dielectric materials for microwave applications,indicating that the sol-gel auto combustion method is a good alternative strategy for the fabrication of CaTiO_(3)-LnAlO_(3) ceramics.