Modulations in the onoratoite system

The iodide form of the mineral onoratoite was synthesized, and like the Cl and Br based analogues, it displays super structure ordering, but for the iodide, the super structure is clearly incommensurate. Due to the poor quality of crystals attainable, the structure was solved by converting the solution of the Cl analogue to a super space formalism, and then using the structural elements from this solution to model the iodide. The structure is triclinic, crystallizing in the 3+1d super space group P-1(αβγ) with the (pseudomonoclinic) cell parameters a = 19.066(8) Å, b = 4.102(2) Å, c = 10.82(6) Å, β = 108.9(2)° and the modulation wave vector q = (0.4716a∗ + 0.25b∗ + 0.1679c∗) been changed accordingly.

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