Titre du document / Document title

Determination of the crystal structure of sanderite, MgSO₄·2H₂O, by X-ray powder diffraction and the charge flipping method

Auteur(s) / Author(s)

HONGWEI MA ; BISH David L. ; WANG Hsiu-Wen ; CHIPERA Steve J. ;

Résumé / Abstract

The crystal structure of sanderite, MgSO₄·2H₂O, was determined from laboratory X-ray powder diffraction data measured from 2-140 °2θ using CuKα radiation. Sanderite is orthorhombic, space group P2₁2₁2₁, with unit-cell parameters a = 8.8932(1) Å, b = 8.4881(1) Å, c = 12.4401(2) Å, V= 939.16(3) ų, Z= 8. The crystal structure model was determined using the charge flipping method and was refined using fundamental parameters Rietveld refinement method to R_wp = 6.52%, R_exp = 1.89%, and Χ² = 3.43. Bond-valence calculations for the refined model show that the structure is chemically reasonable. In the refined structure, Mg²⁺ cations are coordinated by four O atoms from [SO₄]^2- groups and by two H₂O molecules, forming distorted octahedra. By sharing vertex O atoms, [SO₄] tetrahedra and [MgO₄(H₂O)₂] octahedra build up a 3-D framework.

Revue / Journal Title

The American mineralogist   ISSN 0003-004X   CODEN AMMIAY 

Source / Source

2009, vol. 94, n^o4, pp. 622-625 [4 page(s) (article)]

Langue / Language

Anglais

Editeur / Publisher

Mineralogical Society of America, Washington, DC, ETATS-UNIS  (1916) (Revue)

Localisation / Location

INIST-CNRS, Cote INIST : 503, 35400018609769.0220