The modulated structure of intermediate-valent CeCoGa
Author:
Niehaus Oliver1, Hoffmann Rolf-Dieter1, Chevalier Bernard2, Pöttgen Rainer1
Affiliation:
1. Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstrasse 30, 48149 Münster, Germany 2. CNRS, Université de Bordeaux, ICMCB, UPR 9048, F-33600 Pessac, France
Abstract
Abstract
CeCoGa was synthesized by melting of the elements in an arc-melting furnace as well as in a sealed niobium tube in an induction furnace. A further annealing step improves the purity and crystallinity of the samples significantly. Its structure was refined on the basis of single-crystal X-ray diffractometer data at different temperatures. Already at room temperature CeCoGa crystallizes in a superstructure of the HT-CeCoAl type. This superstructure can be described in the (3+1)D superspace group C2/m(α0γ)00; α=2/3, γ=1/3 with a temperature independent q-vector (Z=4). For the 300 K data (also for 90 K) the commensurate modulated structure could be refined with 1336 F
2 values, 56 variables and residuals of wR=0.0348 for the main and wR=0.0605 for the satellites of 1st order [a=1101.7(1), b=436.0(1) and c=482.4(1) pm, β=103.2(1)°]. Furthermore a description in a transformed 3D supercell with the space group C2/m and Z=12 is possible. For the 90 K data this 3D supercell was refined with 1289 F
2 values, 56 variables and a residual of wR=0.0409 [a=1618.8(1), b=435.3(1) and c=1094.1(1) pm, β=119.3(1)°]. The relation of the HT-CeCoAl type structure, the (3+1)D modulated and the 3D supercell structure are discussed on the basis of a group-subgroup relation. By thermal analysis and magnetic measurements the phase transition temperature to the HT-CeCoAl type structure is stated slightly above 475 K. Furthermore intermediate cerium valence was identified by the magnetic susceptibility.
Publisher
Walter de Gruyter GmbH
Subject
Inorganic Chemistry,Condensed Matter Physics,General Materials Science
Reference56 articles.
1. R. Pöttgen, B. Chevalier, Z. Naturforsch. 2015, 70b, 289. 2. R. Pöttgen, H. Borrmann, R. K. Kremer, J. Magn. Magn. Mater. 1996, 152, 196. 3. D. Niepmann, R. Pöttgen, B. Künnen, G. Kotzyba, C. Rosenhahn, B. D. Mosel, Chem. Mater. 1999, 11, 1597. 4. Y. Uwatoko, T. Ishii, G. Oomi, H. Takahashi, N. Mōri, S. Nimori, G. Kido, J. L. Sarrao, D. Mandrus, Z. Fisk, J. D. Thompson, Physica B1997, 237–238, 207. 5. D. T. Adroja, S. K. Malik, B. D. Padalia, R. Vijayaraghavan, Phys. Rev. B1989, 39, 4831.
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