Modifying the valence phase transition in Eu2Al15Pt6 by the solid solutions Eu2Al15(Pt1−x
T
x
)6 (T = Pd, Ir, Au; x = 1/6)
Author:
Engel Stefan1, Schumacher Lars2, Janka Oliver1
Affiliation:
1. Anorganische Festkörperchemie , Universität des Saarlandes , Campus C4.1 , 66123 Saarbrücken , Germany 2. Institut für Anorganische und Analytische Chemie , Universität Münster , Corrensstrasse 28/30 , 48149 Münster , Germany
Abstract
Abstract
The solid solutions Eu2Al15(Pt1−x
T
x
)6 with T = Pd, Ir, Au and x = 1/6 were prepared by arc-melting the stoichiometric mixture of the elements, and subsequent annealing. For x = 1/6, all three solid solutions adopt the same structure type as Eu2Al15Pt6 according to powder X-ray diffraction data. Since the platinide Eu2Al15Pt6 exhibits a (3 + 1)D modulated structure (approximant in space group P121/m1), only the averaged hexagonal unit cell (P63/mmc, Sc0.6Fe2Si4.9 type) was refined by the Rietveld method. Scanning electron microscopy in combination with energy-dispersive X-ray spectroscopy (SEM/EDX) showed that the degree of substitution is in line with the weighed amounts. For values of x > 1/6, no phase-pure samples could be obtained. The results of the magnetic susceptibility measurements indicate that the isoelectronic substitution of Pd for Pt lowers the temperature of the first-order valence phase transition from T
trans = 45 K in Eu2Al15Pt6 to T
trans = 42 K in Eu2Al15(Pt5/6Pd1/6)6. For Eu2Al15(Pt5/6Ir1/6)6 and Eu2Al15(Pt5/6Au1/6)6 a change in the electronic situation occurs since the Ir substituted compound exhibits one electron less compared to the pristine Pt compound, while Eu2Al15(Pt5/6Au1/6)6 has one additional electron. As a consequence, Eu2Al15(Pt5/6Ir1/6)6 shows a higher valence phase transition temperature of T
trans = 52 K while for Eu2Al15(Pt5/6Au1/6)6 no such transition is obvious.
Funder
Deutsche Forschungsgemeinschaft DFG
Publisher
Walter de Gruyter GmbH
Subject
General Chemistry
Reference48 articles.
1. Szytuła, A., Leciejewicz, J., Eds. Handbook of Crystal Structures and Magnetic Properties of Rare Earth Intermetallics; CRC Press: Boca Raton, 1994. 2. Emsley, J. The Elements; Clarendon Press, Oxford University Press: Oxford, New York, 1998. 3. Cotton, S. Lanthanides & Actinides; Macmillan Education: Basingstoke, 1991. 4. Lueken, H. Magnetochemie; B. G. Teubner: Stuttgart, Leipzig, 1999. 5. Heying, B., Kösters, J., Heletta, L., Klenner, S., Pöttgen, R. Monatsh. Chem. 2019, 150, 1163–1173; https://doi.org/10.1007/s00706-019-02412-8.
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