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Structure of Gd3Ru4Al12, a new member of the EuMg5.2structure family with minority-atom clusters

Published in Acta Crystallographica. B, Structural Science. 1993, vol. 49, p. 474-478
Abstract Gd<sub>3</sub>Ru<sub>4+x</sub>All2-x [x = 0.13 (2)], Mr = 1209.44, hexagonal, hP38, P6<sub>3</sub>/mmc – kh<sub>2</sub>g f ba (No. 194), a = 8.8142 (6), c = 9.5692 (9) A, V= 643.8 (1) A<sub>3</sub>, Z = 2, D<sub>x</sub>=6.239Mgm <sup>-3</sup>, A(Mo Ka)=0.71073A, u= 20.330 mm<sup>-1</sup>, F(000) = 1056 (1), T= 293 K, wR=0.023 for 338 contributing unique reflections. Gd<sub>3</sub>Ru<sub>4</sub>AI<sub>12</sub> is a substitution variant of the Sc<sub>3</sub>Ni<sub>11Ge<sub>4</sub> structure which is a partly disordered variant of the Sc<sub>3</sub>Ni<sub>11</sub>Si<sub>4</sub> type, all three structures being ternary substitution derivatives of the EuMg<sub>5.2</sub> or ErZn<sub>5</sub> types. Contrary to the related structure types, in Gd<sub>3</sub>Ru<sub>4</sub>AI<sub>12</sub> both Wyckoff sites 2(a) and 2(b) have full occupation, i.e. an ordered arrange- ment of alternate Ru and AI atoms is observed along the c axis. The structure of Gd<sub>3</sub>Ru<sub>4</sub>AI<sub>12</sub> is built up of two kinds of layers perpendicular to [001]: planar layers of composition Gd<sub>3</sub>Al<sub>4<sub> and puckered layers of composition Ru<sub>4</sub>AI<sub>5</sub>. Similar layers are found in cubic Hf<sub>6</sub>Ni<sub>7</sub>AI<sub>16</sub>, a ternary substitution variant of Th<sub>6</sub>Mn<sub>23</sub>, as well as in hexagonal Sr<sub>9<sub>Mg<sub>38</sub> and BaLi<sub>4</sub>.
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GLADYSHEVSKII, Roman et al. Structure of Gd3Ru4Al12, a new member of the EuMg5.2structure family with minority-atom clusters. In: Acta Crystallographica. B, Structural Science, 1993, vol. 49, p. 474-478. https://archive-ouverte.unige.ch/unige:81204

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