Abstract
The isostructural compounds caesium decasodium tetrazirconium nonaarsenate, CsNa10Zr4(AsO4)9, and caesium decasodium tetrahafnium nonaarsenate, CsNa10Hf4(AsO4)9, arose as unexpected single-crystal products from the reactions of Na2CO3, MO2 (M = Zr, Hf) and As2O5 in a eutectic flux of NaCl and CsCl. They consist of MO6 octahedra and AsO4 tetrahedra sharing vertices to generate three-dimensional polyhedral networks encapsulating the caesium and sodium ions. The MO6 groups share all their vertices with adjacent As atoms but the As atoms have one or two ‘terminal’ O atoms not bonded to Zr or Hf. The Cs+ ion adopts a squashed octahedral geometry and the coordination polyhedra of the partially occupied sodium ions are variously trigonal bipyramidal, tetrahedral, square pyramidal and trigonal pyramidal. Site
symmetries: Cs 3; M 3; As 1 and 2; O 1; Na 1, 2 and 3. The M = Zr crystal
was refined as an obverse/reverse rhombohedral twin.
symmetries: Cs 3; M 3; As 1 and 2; O 1; Na 1, 2 and 3. The M = Zr crystal
was refined as an obverse/reverse rhombohedral twin.
Original language | English |
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Article number | E78 |
Number of pages | 14 |
Journal | Acta Crystallographica Section E |
Volume | 78 |
Issue number | 7 |
Early online date | 1 Jul 2022 |
DOIs | |
Publication status | Published - 1 Jul 2022 |
Bibliographical note
AcknowledgementsWe thank the EPSRC National Crystallography Service (University of Southampton) for the X-ray data collection for (II).
Keywords
- crystal structure
- zirconium
- hafnium
- arsenate
- ionic conduction