Structural and Mechanistic Studies of the Dehydration of MoO2PO3OH·H2O and the In situ Identification of Two New Molybdenum Phosphates
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- 作者：Sarah E. Lister ; Victoria J. Rixom ; John S. O. Evans
- 刊名：Chemistry of Materials
- 出版年：2010
- 出版时间：September 28, 2010
- 年：2010
- 卷：22
- 期：18
- 页码：5279-5289
- 全文大小：1263K
- 年卷期：v.22,no.18(September 28, 2010)
- ISSN：1520-5002
文摘
We report investigations into the dehydration pathway of the precursor material MoO2PO3OH·H2O to γ-(MoO2)2P2O7. The reaction occurs in three distinct stages via the formation of two new previously unidentified molybdenum phosphate phases, β-MoOPO4 and δ-(MoO2)2P2O7. Conditions for the isolation of these phases were identified by a whole powder pattern fitting technique to follow phase evolution versus time and temperature and later verified by full Rietveld refinement. Structural refinement of β-MoOPO4 was performed against X-ray and neutron data. The new phase has lattice parameters a = 7.4043(3) Å, b = 7.2128(3) Å, c = 7.2876(3) Å, β = 118.346(2)°, and volume 342.53(3) Å3 at room temperature, containing 7 unique atoms in space group Cc. δ-(MoO2)2P2O7 forms on slowly heating the precursor material to 793 K. Lattice parameters at room temperature are a = 16.2213(11) Å, b = 3.8936(3) Å, and c = 6.2772(4) Å and volume 396.46(5) Å3, in space group C2221. A transformation mechanism is proposed for the dehydration. Lithium intercalation into layered δ-(MoO2)2P2O7 has been shown.