X-ray Diffraction Study of Superstructure in GdBaCo2O5.5

Abstract

A single crystal of GdBaCo2O5.47(2) has been studied by means of X-ray diffraction. Appearance of superstructure reflections at T = 341.5(7) K gives an evidence of continuous transition to the phase with unit cell doubled along the shortest edge a1. Critical exponent for the order parameter is found to be beta=0.33(1). The superstructure reflections are about 2-4 orders of magnitude weaker than the basic ones. Their systematic extinction indicates the crystal symmetry change from Pmmm to Pmma. The integrated intensities allow to calculate displacements of atoms from the positions in the high-temperature phase. The cobalt-ligand distances in the ordered phase are discussed in terms of the spin-state/orbital ordering of Co3+ ions.

4 pages

References in corpus (7)

• Structural phenomena associated with the spin-state transition in LaCoO3
• Selective Spin-State Switch and Metal-Insulator Transition in \boldmath $\mathrm{GdBaC}{\mathrm{o}}_2{\mathrm{O}}_{5.5}$
• A different look at the spin state of Co${}^{3+}$ ions in CoO${}_5$ pyramidal coordination
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• Magnetic Structures of High Temperature Phases of TbBaCo2O5.5
• Spin state and phase competition in TbBaCo_{2}O_{5.5} and the lanthanide series LnBaCo_{2}O_{5+δ} (0<=δ<=1)
• Magnetization and Magnetotransport of LnBaCo2O5.5 (Ln=Gd, Eu) Single Crystals

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• Magnetic and Electronic properties of Eu0.9Ca0.1BaCo2O5.5+? with the disparity of Oxygen Stoichiometry
• Photo-induced Antiferromagnetic-ferromagnetic Transition and Electronic Structure Modulation in GdBaCo${}_2$O${}_{5.5}$ Thin Film
• Transport and magnetic properties in YBaCo2O5.45: Focus on the high-temperature transition