Exploratory Work in the Quaternary System of Ca–Eu–Cd–Sb: Synthesis, Crystal, and Electronic Structures of New Zintl Solid Solutions
Investigation of the quaternary system, Ca⁻Eu⁻Cd⁻Sb, led to a discovery of the new solid solutions, Ca<sub>1−<i>x</i></sub>Eu<i><sub>x</sub></i>Cd<sub>2</sub>Sb<sub>2</sub>, with the CaAl&...
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doaj-ac8995764a974bb7af535f2ae1a8139d2020-11-25T02:11:16ZengMDPI AGMaterials1996-19442018-10-011111214610.3390/ma11112146ma11112146Exploratory Work in the Quaternary System of Ca–Eu–Cd–Sb: Synthesis, Crystal, and Electronic Structures of New Zintl Solid SolutionsAlexander Ovchinnikov0Gregory M. Darone1Bayrammurad Saparov2Svilen Bobev3Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USADepartment of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USADepartment of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USADepartment of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USAInvestigation of the quaternary system, Ca⁻Eu⁻Cd⁻Sb, led to a discovery of the new solid solutions, Ca<sub>1−<i>x</i></sub>Eu<i><sub>x</sub></i>Cd<sub>2</sub>Sb<sub>2</sub>, with the CaAl<sub>2</sub>Si<sub>2</sub> structure type (<i>x</i> ≈ 0.3⁻0.9, <i>hP</i>5, <i>P</i><inline-formula> <math display="inline"> <semantics> <mrow> <mover accent="true"> <mn>3</mn> <mo stretchy="true">¯</mo> </mover> </mrow> </semantics> </math> </inline-formula><i>m</i>1, <i>a</i> = 4.6632(5)⁻4.6934(3) Å, <i>c</i> = 7.630(1)⁻7.7062(7) Å), Ca<sub>2−<i>x</i></sub>Eu<i><sub>x</sub></i>CdSb<sub>2</sub> with the Yb<sub>2</sub>CdSb<sub>2</sub> type (<i>x</i> ≈ 0.6, <i>oS</i>20, <i>Cmc</i>2<sub>1</sub>, <i>a</i> = 4.646(2) Å, <i>b</i> = 17.733(7) Å, <i>c</i> = 7.283(3) Å), and Eu<sub>11−<i>x</i></sub>Ca<i><sub>x</sub></i>Cd<sub>6</sub>Sb<sub>12</sub> with the Sr<sub>11</sub>Cd<sub>6</sub>Sb<sub>12</sub> type (<i>x</i> ≈ 1, <i>mS</i>58, <i>C</i>2/<i>m</i>, <i>a</i> = 32.407(4) Å, <i>b</i> = 4.7248(5) Å, <i>c</i> = 12.377(1) Å, <i>β</i> = 109.96(1)°). Systematic crystallographic studies of the Ca<sub>1−<i>x</i></sub>Eu<i><sub>x</sub></i>Cd<sub>2</sub>Sb<sub>2</sub> series indicated expansion of the unit cell upon an increase in the Eu content, in accordance with a larger ionic radius of Eu<sup>2+</sup> vs. Ca<sup>2+</sup>. The Ca<sub>2−<i>x</i></sub>Eu<i><sub>x</sub></i>CdSb<sub>2</sub> composition with <i>x</i> ≈ 0.6 adopts the non-centrosymmetric space group, <i>Cmc</i>2<sub>1</sub>, although the parent ternary phase, Ca<sub>2</sub>CdSb<sub>2</sub>, crystallizes in the centrosymmetric space group, <i>Pnma</i>. Two non-equivalent Ca sites in the layered crystal structure of Ca<sub>2−<i>x</i></sub>Eu<i><sub>x</sub></i>CdSb<sub>2</sub> get unevenly occupied by Eu, with a preference for the interlayer position, which offers a larger available volume. Similar size-driven preferred occupation is observed in the Eu<sub>11−<i>x</i></sub>Ca<i><sub>x</sub></i>Cd<sub>6</sub>Sb<sub>12</sub> solid solution with <i>x</i> ≈ 1.https://www.mdpi.com/1996-1944/11/11/2146Zintl phasesantimonidescrystal structurechemical bonding |
| collection |
DOAJ |
| language |
English |
| format |
Article |
| sources |
DOAJ |
| author |
Alexander Ovchinnikov Gregory M. Darone Bayrammurad Saparov Svilen Bobev |
| spellingShingle |
Alexander Ovchinnikov Gregory M. Darone Bayrammurad Saparov Svilen Bobev Exploratory Work in the Quaternary System of Ca–Eu–Cd–Sb: Synthesis, Crystal, and Electronic Structures of New Zintl Solid Solutions Materials Zintl phases antimonides crystal structure chemical bonding |
| author_facet |
Alexander Ovchinnikov Gregory M. Darone Bayrammurad Saparov Svilen Bobev |
| author_sort |
Alexander Ovchinnikov |
| title |
Exploratory Work in the Quaternary System of Ca–Eu–Cd–Sb: Synthesis, Crystal, and Electronic Structures of New Zintl Solid Solutions |
| title_short |
Exploratory Work in the Quaternary System of Ca–Eu–Cd–Sb: Synthesis, Crystal, and Electronic Structures of New Zintl Solid Solutions |
| title_full |
Exploratory Work in the Quaternary System of Ca–Eu–Cd–Sb: Synthesis, Crystal, and Electronic Structures of New Zintl Solid Solutions |
| title_fullStr |
Exploratory Work in the Quaternary System of Ca–Eu–Cd–Sb: Synthesis, Crystal, and Electronic Structures of New Zintl Solid Solutions |
| title_full_unstemmed |
Exploratory Work in the Quaternary System of Ca–Eu–Cd–Sb: Synthesis, Crystal, and Electronic Structures of New Zintl Solid Solutions |
| title_sort |
exploratory work in the quaternary system of ca–eu–cd–sb: synthesis, crystal, and electronic structures of new zintl solid solutions |
| publisher |
MDPI AG |
| series |
Materials |
| issn |
1996-1944 |
| publishDate |
2018-10-01 |
| description |
Investigation of the quaternary system, Ca⁻Eu⁻Cd⁻Sb, led to a discovery of the new solid solutions, Ca<sub>1−<i>x</i></sub>Eu<i><sub>x</sub></i>Cd<sub>2</sub>Sb<sub>2</sub>, with the CaAl<sub>2</sub>Si<sub>2</sub> structure type (<i>x</i> ≈ 0.3⁻0.9, <i>hP</i>5, <i>P</i><inline-formula> <math display="inline"> <semantics> <mrow> <mover accent="true"> <mn>3</mn> <mo stretchy="true">¯</mo> </mover> </mrow> </semantics> </math> </inline-formula><i>m</i>1, <i>a</i> = 4.6632(5)⁻4.6934(3) Å, <i>c</i> = 7.630(1)⁻7.7062(7) Å), Ca<sub>2−<i>x</i></sub>Eu<i><sub>x</sub></i>CdSb<sub>2</sub> with the Yb<sub>2</sub>CdSb<sub>2</sub> type (<i>x</i> ≈ 0.6, <i>oS</i>20, <i>Cmc</i>2<sub>1</sub>, <i>a</i> = 4.646(2) Å, <i>b</i> = 17.733(7) Å, <i>c</i> = 7.283(3) Å), and Eu<sub>11−<i>x</i></sub>Ca<i><sub>x</sub></i>Cd<sub>6</sub>Sb<sub>12</sub> with the Sr<sub>11</sub>Cd<sub>6</sub>Sb<sub>12</sub> type (<i>x</i> ≈ 1, <i>mS</i>58, <i>C</i>2/<i>m</i>, <i>a</i> = 32.407(4) Å, <i>b</i> = 4.7248(5) Å, <i>c</i> = 12.377(1) Å, <i>β</i> = 109.96(1)°). Systematic crystallographic studies of the Ca<sub>1−<i>x</i></sub>Eu<i><sub>x</sub></i>Cd<sub>2</sub>Sb<sub>2</sub> series indicated expansion of the unit cell upon an increase in the Eu content, in accordance with a larger ionic radius of Eu<sup>2+</sup> vs. Ca<sup>2+</sup>. The Ca<sub>2−<i>x</i></sub>Eu<i><sub>x</sub></i>CdSb<sub>2</sub> composition with <i>x</i> ≈ 0.6 adopts the non-centrosymmetric space group, <i>Cmc</i>2<sub>1</sub>, although the parent ternary phase, Ca<sub>2</sub>CdSb<sub>2</sub>, crystallizes in the centrosymmetric space group, <i>Pnma</i>. Two non-equivalent Ca sites in the layered crystal structure of Ca<sub>2−<i>x</i></sub>Eu<i><sub>x</sub></i>CdSb<sub>2</sub> get unevenly occupied by Eu, with a preference for the interlayer position, which offers a larger available volume. Similar size-driven preferred occupation is observed in the Eu<sub>11−<i>x</i></sub>Ca<i><sub>x</sub></i>Cd<sub>6</sub>Sb<sub>12</sub> solid solution with <i>x</i> ≈ 1. |
| topic |
Zintl phases antimonides crystal structure chemical bonding |
| url |
https://www.mdpi.com/1996-1944/11/11/2146 |
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