Hydrothermal synthesis, crystal structure and thermal transformation of a new zinc arsenate hydrate, Zn9(AsO4)6·4H2O

Torben R. Jensen*, Poul Norby, Jonathan C. Hanson, Eivind M. Skou, P. C. Stein

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

A new synthetic polymorph of zinc arsenate hydrate, Zn9(AsO4)6·4H2O, was prepared from an aqueous solution. Owing to the small size of the crystals, synchrotron X-ray radiation was applied for the indexing and data collection. An initial structural model was found from 1819 unique reflections measured (space group P1̄, refined to wR = 0.154, R = 0.060). Optimisation of the synthesis conditions provided larger crystals for crystallographic measurements using a conventional diffractometer: a = 6.6895(3), b = 9.1761 (4), c = 10.1377(8) Å, α = 69.428(5), β = 77.205(5), γ = 75.765(4)°, space group P1̄ The structure was refined to wR = 0.072, R = 0.061. The crystal structure of Zn9(AsO4)6·4H2O is built from chains of edge-sharing octahedra and trigonal-bipyramidal Zn atoms co-ordinated to framework oxygen and water molecule oxygen atoms. These chains are connected by tetrahedra of Zn and As co-ordinated to framework oxygen atoms. Channels run along the a axis where the water molecules are placed. The compound transforms into a new phase of Zn3(AsO4)2 at 424(1)°C and into the known phase β-Zn3(AsO4)2 at 865(1)°C.

Original languageEnglish
JournalJournal of the Chemical Society - Dalton Transactions
Issue number4
Pages (from-to)527-532
Number of pages6
ISSN0300-9246
DOIs
Publication statusPublished - 1. Jan 1998

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