Concentration- and Temperature-Induced Phase Transitions in PrAlO3-SrTiO3 System.

Leonid Vasylechko,Yuri Prots,Roman Stepchuk,Helge Rosner

doi:10.1186/s11671-015-1225-4

Abstract

Single-phase mixed aluminates-titanates Pr1−xSrxAl1−xTixO3 (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 Pr1−xSrxAl1−xTixO3 series is predicted to occur at x = 0.88. The temperature-induced structural phase transition R overline{3} с − Pm overline{3} m in Pr0.5Sr0.5Al0.5Ti0.5O3, 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 PrAlO3 (1770 K). Such remarkable drop of the transition temperature is explained by gradual decrease of the perovskite structure deformation in the Pr1−xSrxAl1−xTixO3 series with increasing Sr and Ti contents as a consequence of the increasing Goldschmidt tolerance factor. For Pr0.3Sr0.7Al0.3Ti0.7O3 phase, a sequence of the low-temperature phase transformation R overline{3} с − Immb(C2/m) − I4/mcm was detected.

Highlights

Rare earth aluminates RAlO3 with perovskite structure and SrTiO3-based materials show diverse technological application
The aim of the present work is the study of the phase and structural behaviour of the mixed aluminatestitanates formed in the PrAlO3–SrTiO3 pseudo-binary system
The formation of extended solid solution Pr1−xSrxAl1 −xTixO3 with rhombohedral perovskite structure has been revealed in the PrAlO3–SrTiO3 pseudo-binary system based on X-ray powder diffraction data

Summary

Introduction

Rare earth aluminates RAlO3 with perovskite structure and SrTiO3-based materials show diverse technological application. They are used as solid electrolytes and anode materials in solid oxide fuel cells, as substrates for thin film epitaxy, materials for laser hosts, scintillates and phosphors, high-temperature ceramics and refractory materials ([1,2,3,4,5] and references ). Due to the opposite signs of the temperature coefficient of the resonant frequency (τf ) of the RAlO3 and SrTiO3 compounds, mixed aluminates-titanates formed in the RAlO3–SrTiO3 systems are considered as prospective microwave materials with a high dielectric constant, moderate quality factor and a near zero value of τf [5,6,7].

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