Structural phase transitions at high-temperature in double perovskite Sr2GdRuO6 |
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Authors: | C.A. Triana,L.T. CorredorD.A. Landí nez Té llez,J. Roa-Rojas |
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Affiliation: | Grupo de Física de Nuevos Materiales, Departamento de Física, Universidad Nacional de Colombia, A.A. 14490, Bogotá D.C, Colombia |
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Abstract: | The crystal structure evolution of the Sr2GdRuO6 complex perovskite at high-temperature has been investigated over a wide temperature range between 298 K≤T≤1273 K. Powder X-ray diffraction measurements at room temperature and Rietveld analysis show that this compounds crystallizes in a monoclinic perovskite-type structure with P21/n (#14) space group and the 1:1 ordered arrangement of Ru5+ and Gd3+ cations over the six-coordinate M sites, with lattice parameters a=5.81032(8) Å, b=5.82341(4) Å, c=8.21939(7) Å, V=278.11(6) Å3 and angle β=90.311(2)o. The high-temperature analysis shows that this material suffers two-phase transitions. At 373 K it adopts a monoclinic perovskite structure with I2/m space group, and lattice parameters a=5.81383(2) Å, b=5.82526(4) Å, c=8.22486(1) Å, V=278.56(2) Å3 and angle β=90.28(2)o. Above of 773 K, it suffers a phase transition from monoclinic I2/m to tetragonal I4/m, with lattice parameters a=5.84779(1) Å, c=8.27261(1) Å, V=282.89(5) Å3 and angle β=90.02(9)o. The high-temperature phase transition from monoclinic I2/m to tetragonal I4/m is characterized by strongly anisotropic displacements of the anions. |
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Keywords: | X-ray powder diffraction Complex perovskite Crystal structure Phase transitions |
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