Concentration- and Temperature-Induced Phase Transitions in PrAlO(3)–SrTiO(3) System

Single-phase mixed aluminates-titanates Pr(1−x)Sr(x)Al(1−x)Ti(x)O(3) (x = 0.1, 0.2, 0.3, 0.5, 0.7) with rhombohedral perovskite structure were prepared by solid-state reaction technique at 1823–1873 K. Morphotropic rhombohedral-to-cubic phase transition in Pr(1−x)Sr(x)Al(1−x)Ti(x)O(3) series is predicted to occur at x = 0.88. The temperature-induced structural phase transition R [Formula: see text] с − Pm[Formula: see text] m in Pr(0.5)Sr(0.5)Al(0.5)Ti(0.5)O(3), detected at 930 K by in situ high-temperature X-ray synchrotron powder diffraction, occurs at considerably lower temperature as the corresponding transformation in the parent compound PrAlO(3) (1770 K). Such remarkable drop of the transition temperature is explained by gradual decrease of the perovskite structure deformation in the Pr(1−x)Sr(x)Al(1−x)Ti(x)O(3) series with increasing Sr and Ti contents as a consequence of the increasing Goldschmidt tolerance factor. For Pr(0.3)Sr(0.7)Al(0.3)Ti(0.7)O(3) phase, a sequence of the low-temperature phase transformation R [Formula: see text] с − Immb(C2/m) − I4/mcm was detected.