Temperature and composition induced phase transitions in Sr2−xCa1+xTeO6 (0 ≤ x ≤ 2) double perovskite oxides

• Published in: Journal of molecular structure Vol. 1131; pp. 103 - 113
• Main Authors: Tamraoui, Y., Manoun, Bouchaib, Mirinioui, F., Saadoune, I., Haloui, R., Elhachmi, A., Saad, E., Lazor, P.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 05-03-2017
• Subjects: Crystal structure; Inorganic compounds; Phase transition; Raman spectroscopy; X-ray diffraction; X-ray diffraction; Inorganic compounds; Raman spectroscopy; Crystal structure; Phase transition
• ISSN: 0022-2860; 1872-8014; 1872-8014
• DOI: 10.1016/j.molstruc.2016.11.036

Structures of Sr2−xCa1+xTeO6 double perovskites have been studied by the profile analysis of X-ray diffraction data and Raman spectroscopy at room temperature. This series adopts a monoclinic symmetry for the compositions (0 ≤ x ≤ 0.5) with P21/n as space group and a triclinic system with P1¯ space group for the compositions (0.5 < x ≤ 2). These results were confirmed by the observed tolerance factor calculated from the distances obtained from the Rietveld refinements which indicates that the true tilt system for the compositions range (0.5 < x ≤ 2) is the triclinic tilt system. Clear changes in the Raman modes centered at 600, 610 and 620 cm−1 and the FWHM of OTeO bending vibrations, centered at 738 cm−1 confirmed that the triclinic symmetry takes place between the compositions x = 0.5 and x = 1. Furthermore, Raman spectroscopy studies at high temperature were done for Ca3TeO6. For this compound, considerable changes in the temperature dependence of the modes were well illustrated.
•Synthesis and characterization of new double perovskites Sr2−xCa1+xTeO6 (0 ≤ x ≤ 2).•High temperature studies of Sr2−xCa1+xTeO6 double perovskite using Raman spectroscopy.•Temperature and compositions induced phase transitions in these materials.•Structural determination/refinement of these compounds as a function of composition.