Crystal structure and microwave dielectric properties of SrTiO3 doped LaALO3 single crystal grown by FZ

(La1−xSrx)(Al1−xTix)O3 solid solutions reveal higher quality factor (Q × f) than that of pure LaAlO3. We propose the use of (La1−xSrx)(Al1−xTix)O3 single crystals for a substrate of high temperature superconductive (HTS) filters. The single crystal of the (La1−xSrx)(Al1−xTix)O3 (x = 0.005, 0.2) was grown by using a floating zone (FZ) method to investigate the relationship between the microwave dielectric properties and the crystal structure. Analysis of the grown (La0.8Sr0.2)(Al0.8Ti0.2)O3 crystal was performed using a X-ray diffraction method. Although the crystal structure of pure LaAlO3 is trigonal (R3¯m, no. 166), the SrTiO3 doped LaAlO3 had stabilized cubic symmetry (Pm3¯m, no. 221), which corresponds to high temperature phase of pure LaAlO3. The refined structure of (La0.8Sr0.2)(Al0.8Ti0.2)O3 exhibited ideal perovskite structure with the angle between O–B–O of 90.0°. This is related to improvement of Q × f value of LaAlO3.