Two New Arsenides, Eu<sub>7</sub>Cu<sub>44</sub>As<sub>23</sub> and Sr<sub>7</sub>Cu<sub>44</sub>As<sub>23</sub>, With a New Filled Variety of the BaHg<sub>11</sub> Structure
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posted on 2014-10-20, 00:00 authored 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. ShevelkovTwo new ternary arsenides, namely,
Eu<sub>7</sub>Cu<sub>44</sub>As<sub>23</sub> and Sr<sub>7</sub>Cu<sub>44</sub>As<sub>23</sub>, were synthesized from elements at 800 °C.
Their crystal structure represents a new filled version of the BaHg<sub>11</sub> motif with cubic voids alternately occupied by Eu(Sr) and
As atoms, resulting in a 2 × 2 × 2 superstructure of the
aristotype: space group <i>Fm</i>3̅<i>m</i>, <i>a</i> = 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.
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