An X-ray diffraction, magnetic susceptibility and spectroscopic studies of Yb2−xCrxO3 |
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Authors: | S Hamdi EK Hlil |
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Institution: | a Unité de Recherche de Chimie des Matériaux, ISSBAT, Université Tunis ElManar, 9 Avenue Dr. Zouhaier Safi, 1006 Tunis, Tunisia b Institut Néel CNRS, Département MCMF, B.P. 166, 38042 Grenoble Cedex 9, France |
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Abstract: | Polycrystalline samples with general formula Yb2−xCrxO3 (0<x<0.03), obtained by sol-gel method and analyzed by X-ray diffraction, formed solid solutions over all the mentioned range. Cr showed a maximum solubility of 2.8 mol% in Yb2O3 sesquioxide at 1000 °C. A preferential substitution of Cr3+ ions over two cationic sites, 8b and 24d in the space group Ia-3 was found. The lattice parameters a are found to vary linearly (10.4402(4) Å <a<10.4372(1) Å) with the composition x. The two independent atoms Yb/Cr have octahedral coordination; however, the degrees of distortion of their coordination polyhedron are different. Replacing Yb3+ by Cr3+ introduces slight changes in the atomic coordinates leading to an increase of the mean cation-anion distances. The ability of Raman spectroscopy to detect changes in local coordination is utilized. A pseudo-tetrahedral coordination for the Cr3+ in the 24d site was found. Magnetic susceptibility measurements of all samples were done in a temperature range of 2-50 K. For T<37 K, the inverse paramagnetic susceptibilities depend linearly on temperature. However, in the high-temperature region, for T>37 K, the inverse paramagnetic susceptibilities are non-linear versus temperature. This deviation from the Curie-Weiss behaviour was discussed. |
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Keywords: | Cr doping C-type sesquioxide Sol-gel Yb2O3 Magnetic measurements Raman spectroscopy |
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