Single Crystal Growth and Structural Study of the New <i>M</i>Cu<sub>2</sub>Zn<sub>20</sub> (<i>M</i> = Nb, Hf) Compounds
Two new cage-structured compounds—NbCu<sub>2</sub>Zn<sub>20</sub> and HfCu<sub>2</sub>Zn<sub>20</sub>—belonging to the <i>MM’</i><sub>2</sub><i>X</i><sub>20</sub> (<i>M</i>, <i>M’</i&...
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| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-04-01
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| Series: | Crystals |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2073-4352/15/5/391 |
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| Summary: | Two new cage-structured compounds—NbCu<sub>2</sub>Zn<sub>20</sub> and HfCu<sub>2</sub>Zn<sub>20</sub>—belonging to the <i>MM’</i><sub>2</sub><i>X</i><sub>20</sub> (<i>M</i>, <i>M’</i> = transition or rare earth metals, and <i>X</i> = Al, Zn, or Cd) family of structures have been synthesized via the self-flux method. The new compounds crystallize in the space group <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>F</mi><mi>d</mi><mover accent="true"><mrow><mn>3</mn></mrow><mo>¯</mo></mover><mi>m</mi></mrow></semantics></math></inline-formula> with lattice parameter 13.9013(2) Å for NbCu<sub>2</sub>Zn<sub>20</sub> and 13.9856(2) Å for HfCu<sub>2</sub>Zn<sub>20</sub>. The structures follow the expected metallic radii trend in <i>MM’</i><sub>20</sub>Zn<sub>20</sub> (<i>M</i> = Nb or Hf, <i>M’</i> = Mn, Fe, Co, Ni, and Cu). While NbCu<sub>2</sub>Zn<sub>20</sub> is stoichiometric, HfCu<sub>2</sub>Zn<sub>20</sub> exhibits Cu/Zn site mixing and Hf-site underoccupancy, resulting in a final stoichiometry of Hf<sub>0.96</sub>Cu<sub>1.67</sub>Zn<sub>20.33</sub> (Hf<sub>1–δ</sub>Cu<sub>2–</sub><i><sub>x</sub></i>Zn<sub>20+</sub><i><sub>x</sub></i>, δ = 0.04, <i>x</i> = 0.33). |
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| ISSN: | 2073-4352 |