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X-ray powder diffraction analysis of a new magnesium chromate hydrate, MgCrO4·11H2O
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- Journal:
- Powder Diffraction / Volume 27 / Issue 1 / March 2012
- Published online by Cambridge University Press:
- 03 April 2012, pp. 8-11
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- Article
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A new hydrate of magnesium chromate is synthesized by quenching aqueous solutions of MgCrO4 in liquid nitrogen. MgCrO4·11H2O is isostructural with the rare mineral meridianiite (MgSO4·11H2O) being triclinic,
, Z = 2, with unit-cell parameters a = 6.811 33(8) Å, b = 6.958 39(9) Å, c = 17.3850(2) Å, α = 87.920(1)°, β = 89.480(1)°, γ = 62.772(1)°, and V = 732.17(1) Å3 at −15 °C. The difference in unit-cell parameters between SO4- and CrO4-bearing species is only partially accounted for by the difference in S–O and Cr–O bond lengths; the remainder of the difference (over 90% in the cell volume) is attributed to weakening of the interpolyhedral hydrogen-bond network.
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