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Two New Arsenides, Eu7Cu44As23 and Sr7Cu44As23, With a New Filled Variety of the BaHg11 Structure

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posted on 20.10.2014, 00:00 by Dmitri O. Charkin, Roman Demchyna, Yurii Prots, Horst Borrmann, Ulrich Burkhardt, Ulrich Schwarz, Walter Schnelle, Igor V. Plokhikh, Sergey M. Kazakov, Artem M. Abakumov, Dmitry Batuk, Valery Yu. Verchenko, Alexander A. Tsirlin, Caroline Curfs, Yuri Grin, Andrei V. Shevelkov
Two new ternary arsenides, namely, Eu7Cu44As23 and Sr7Cu44As23, were synthesized from elements at 800 °C. Their crystal structure represents a new filled version of the BaHg11 motif with cubic voids alternately occupied by Eu­(Sr) and As atoms, resulting in a 2 × 2 × 2 superstructure of the aristotype: space group Fmm, a = 16.6707(2) Å and 16.7467(2) Å, respectively. The Eu derivative exhibits ferromagnetic ordering below 17.5 K. In agreement with band structure calculations both compounds are metals, exhibiting relatively low thermopower, but high electrical and low thermal conductivity.