Research on microwave dielectric properties of LaAlO₃-SrTiO₃ ceramics with high quality factor

High-quality (1-x)LaAlO₃-xSrTiO₃ ceramics were prepared by the solid state reaction method, the effects of SrTiO₃ addition on the properties and structure of LaAlO₃-SrTiO₃ ceramics were studied. The results show that as x equals to 0.54-0.63, LaAlO₃ and SrTiO₃ form perovskite solid solution, and the perovskite is constrain cubic structure. At the best craft conditions, all the samples show a compact structure, few air bubbles and distinct crystal boundary, the density of (1-x)LaAlO₃-xSrTiO₃ ceramics decreases from 5.45 g/cm³ to 5.28 g/cm³, almost linearly with x value, ε_r increases from 38.9 to 48.35, τ_f increases from -12×10^-6/℃ to +19×10^-6/℃, Q·f value decreases from 75057 GHz to 48629 GHz. As the x=0.6, the 0.6SrTiO₃-0.4LaAlO₃ ceramics sintered at 1550 ℃ for 3 h exhibit an excellent combination of microwave dielectric properties: ε_r=45.27, Q·f=57677 GHz, τ_f=+1×10^-6/℃.