Y<sub>5</sub>F<sub>3</sub>[AsO<sub>3</sub>]<sub>4</sub> and Y<sub>5</sub>Cl<sub>3</sub>[AsO<sub>3</sub>]<sub>4</sub>: Two Non-Isostructural Yttrium Halide Oxoarsenates(III) and Their Potential as Hosts for Luminescent Eu<sup>3+</sup>- and Tb<sup>3+</sup>-Doping
Y<sub>5</sub>F<sub>3</sub>[AsO<sub>3</sub>]<sub>4</sub> crystallizes needle-shaped in the tetragonal space group <i>P</i>4/<i>ncc</i> with the lattice parameters <i>a</i> = 1143.80(8) pm, <i>c</i> = 1078....
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| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-06-01
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| Series: | Crystals |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2073-4352/15/7/611 |
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| Summary: | Y<sub>5</sub>F<sub>3</sub>[AsO<sub>3</sub>]<sub>4</sub> crystallizes needle-shaped in the tetragonal space group <i>P</i>4/<i>ncc</i> with the lattice parameters <i>a</i> = 1143.80(8) pm, <i>c</i> = 1078.41(7) pm and <i>c</i>/<i>a</i> = 0.9428 for <i>Z</i> = 4. The yttrium-fluoride substructure linked via secondary contacts forms a three-dimensional network <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mtable><mtr><mtd><mn>3</mn></mtd></mtr><mtr><mtd><mo>∞</mo></mtd></mtr></mtable></mrow></semantics></math></inline-formula>{[Y<sub>5</sub>F<sub>3</sub>]<sup>12+</sup>} and the remaining part consists of ψ<sup>1</sup>-tetrahedral [AsO<sub>3</sub>]<sup>3−</sup> units, which leave lone-pair channels along [001]. In contrast, platelet-shaped Y<sub>5</sub>Cl<sub>3</sub>[AsO<sub>3</sub>]<sub>4</sub> crystals adopt the monoclinic space group <i>C</i>2/<i>c</i> with the lattice parameters <i>a</i> = 1860.56(9) pm, <i>b</i> = 536.27(3) pm, <i>c</i> = 1639.04(8) pm and <i>β</i> = 105.739(3)° for <i>Z</i> = 4. Condensation of [(Y1,2)O<sub>8</sub>]<sup>13−</sup> polyhedra via four common edges each leads to fluorite-like <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mtable><mtr><mtd><mn>2</mn></mtd></mtr><mtr><mtd><mo>∞</mo></mtd></mtr></mtable></mrow></semantics></math></inline-formula> {[(Y1,2)O <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mtable><mtr><mtd><mi>e</mi></mtd></mtr><mtr><mtd><mrow><mrow><mn>8</mn></mrow><mo>/</mo><mrow><mn>2</mn></mrow></mrow></mtd></mtr></mtable></mrow></semantics></math></inline-formula> ]<sup>5−</sup>} layers spreading out parallel to the (100) plane. Their three-dimensional linkage occurs via the (Y3)<sup>3+</sup> cations with their Cl<sup>−</sup> ligands on the one hand and the As<sup>3+</sup> cations with their lone-pairs of electrons on the other, which also form within [AsO<sub>3</sub>]<sup>3−</sup> anions lone-pair channels along [010]. Both colorless compounds can be obtained by solid-state reactions from corresponding mixtures of the binaries (Y<sub>2</sub>O<sub>3</sub>, As<sub>2</sub>O<sub>3</sub> and YX<sub>3</sub> with X = F and Cl) at elevated temperatures of 825 °C, most advantageously under halide-flux assistance (CsBr for Y<sub>5</sub>F<sub>3</sub>[AsO<sub>3</sub>]<sub>4</sub> and ZnCl<sub>2</sub> for Y<sub>5</sub>Cl<sub>3</sub>[AsO<sub>3</sub>]<sub>4</sub>). By replacing a few percent of YX<sub>3</sub> with EuX<sub>3</sub> or TbX<sub>3</sub>, Eu<sup>3+</sup>- or Tb<sup>3+</sup>-doped samples are accessible, which show red or green luminescence upon excitation with ultraviolet radiation. |
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| ISSN: | 2073-4352 |