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X-ray powder diffraction analysis of two new magnesium selenate hydrates, MgSeO4·9H2O and MgSeO4·11H2O

  • A. Dominic Fortes (a1) (a2)


Several hitherto unknown hydrates of magnesium selenate have been formed by quenching aqueous solutions of MgSeO4 in liquid nitrogen. MgSeO4·11H2O is apparently isostructural with the mineral meridianiite (MgSO4·11H2O), being triclinic, $P{\rm \bar 1}$ , Z = 2, with unit-cell parameters a = 6.779 00(8) Å, b = 6.965 16(9) Å, c = 17.4934(2) Å, α = 87.713(1)°, β = 89.222(1)°, γ = 63.121(1)°, and V = 736.15(1) Å3 at −25 °C. MgSeO4·9H2O represents a new hydration state in the MgSeO4–H2O system; it is monoclinic, space-group P21 /c, Z = 4, with unit-cell parameters a = 7.270 24(6) Å, b = 10.510 94(9) Å, c = 17.4030(2) Å, β = 109.447(1)°, and V = 1254.02(1) Å3 at −22 °C. The heavy-atom structure of MgSeO4·9H2O has been determined by direct-space methods from X-ray powder diffraction data and consists of isolated Mg(H2O)6 2+ octahedra and SeO4 2− tetrahedra linked by hydrogen bonds. The remaining three water molecules occupy the space between the polyhedral ions, contributing to the H-bonded network, which comprises 4-, 5-, and 6-membered rings. A third phase has been observed to crystallise prior to the 11-hydrate upon warming of liquid-nitrogen-quenched glass, but this transforms rapidly to the meridianiite-structured 11-hydrate and the identity of this phase is unclear.


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Baur, W. H. (1964). “On the crystal chemistry of salt hydrates. IV. The refinement of the crystal structure of MgSO4·7H2O (epsomite),” Acta Crystallogr. 17, 13611369.
Boultif, A. and Louër, D. (2004). “Powder pattern indexing with the dichotomy method,” J. Appl. Cryst. 37, 724731.
Brand, H. E. A., Fortes, A. D., Wood, I. G., Knight, K. S., and Vočadlo, L. (2009). “The thermal expansion and crystal structure of mirabilite (Na2SO4·10D2O) from 4.2–300 K, determined by time-of-flight neutron powder diffraction,” Phys. Chem. Min. 36, 2946.
De Wolff, P. M. (1968). “A simplified criterion for the reliability of a powder pattern indexing,” J. Appl. Cryst. 5, 108113.
Favre-Nicolin, V. and Černý, R. (2002). “FOX, ‘free objects for crystallography’: a modular approach to ab initio structure determination from powder diffraction,” J. Appl. Cryst. 35, 734743.
Favre-Nicolin, V. and Černý, R. (2004). “A better FOX: using flexible modeling and maximum likelihood to improve direct-space ab initio structure determination from powder diffraction,” Z. Krist. 219, 847856.
Ferraris, G., Jones, D. W., and Yerkess, J. (1973). “Refinement of the crystal structure of magnesium sulphate heptahydrate (epsomite) by neutron diffraction,” J. Chem. Soc. Dalton Trans. 1973, 816821.
Fortes, A. D. (2014). Analogue materials for high-pressure studies of planetary ices, in British Crystallographic Society Spring Meeting, Loughborough, April 8th 2014.
Fortes, A. D. and Gutmann, M. J. (2014). “Crystal structure of magnesium selenate heptahydrate, MgSeO4·7H2O, from neutron time-of-flight data,” Acta Crystallogr. Sect. E. 70, 134137.
Fortes, A. D. and Wood, I. G. (2012). “X-ray powder diffraction analysis of a new magnesium chromate hydrate, MgCrO4·11H2O,” Powder Diffr. 27, 811.
Fortes, A. D., Wood, I. G., Grigoriev, D., Alfredsson, M., Kipfstuhl, S., Knight, K. S., and Smith, R. I. (2004). “No evidence of large-scale proton ordering in Antarctic ice from powder neutron diffraction,” J. Chem. Phys. 120, 1137611379.
Fortes, A. D., Wood, I. G., and Knight, K. S. (2008). “The crystal structure and thermal expansion tensor of MgSO4·11D2O (meridianiite) determined by neutron powder diffraction,” Phys. Chem. Min. 35, 207221.
Fortes, A. D., Wood, I. G., and Tucker, M. G. (2009). The effect of pressure on the structure of meridianiite (MgSO 4 ·11D 2 O). ISIS Experimental Report, RB910226, Rutherford Appleton Laboratory, Oxford, UK.
Fortes, A. D., Browning, F., and Wood, I. G. (2012a). “Cation substitution in synthetic meridianiite (MgSO4·11H2O) I: X-ray powder diffraction analysis of quenched polycrystalline aggregates,” Phys. Chem. Min. 39, 419441.
Fortes, A. D., Browning, F., and Wood, I. G. (2012b). “Cation substitution in synthetic meridianiite (MgSO4·11H2O) II: variation in unit-cell parameters determined from X-ray powder diffraction data,” Phys. Chem. Min. 39, 443454.
Fortes, A. D., Wood, I. G., and Fernandez-Alonso, F. (2012c). Thermoelastic properties and high-pressure decomposition of MgSO 4 ·11D 2 O. ISIS Experimental Report, RB1110039, Rutherford Appleton Laboratory, Oxford, UK.
Fortes, A. D., Wood, I. G., and Gutmann, M. J. (2013). “MgSO4·11H2O and MgCrO4·11H2O from time-of-flight neutron single-crystal Laue data,” Acta Crystallogr. Sect. C 69, 324329.
Genceli, F. E., Shinochirou, H., Yoshinori, I., Toshimitsu, S., Hondoh, T., Kawamura, T., and Witkamp, G.-J. (2009). “Meridianiite detected in ice,” J. Glaciol. 55, 117122.
Kamburov, S., Schmidt, H., Voigt, W., and Balarew, C. (2014). “Similarities and peculiarities between the crystal structures of the hydrates of sodium sulfate and selenate,” Acta Crystallogr. Sect. B 70, 714722.
Kargel, J. S. (1991). “Brine volcanism and the interior structures of asteroids and icy satellites,” Icarus 94, 368390.
Klein, A. (1940). “Étude sur les séléniates des métaux de la série magnésienne,” Ann. Chim. 14, 263317.
Kolitsch, U. (2001). “Copper(II) selenate pentahydrate, CuSeO4·5H2O,” Acta Crystallogr. Sect. E 57, i104i105.
Kolitsch, U. (2002). “Magnesium selenate hexahydrate, MgSeO4·6H2O,” Acta Crystallogr., Sect. E 58, i3i5.
Krivovichev, S. V. (2007). “Crystal chemistry of selenates with mineral-like structures. III. Heteropolyhedral chains in the crystal structure of [Mg(H2O)4(SeO4)]2(H2O),” Geol. Ore Dep. 49(7), 537541.
Larson, A. C. and Von Dreele, R. B. (2000). General Structure Analysis System (GSAS). Los Alamos National Laboratory Report, LAUR 86-748.
Meyer, J. and Aulich, W. (1928). “Zur kenntnis der doppelsalze der selensäure,” Z. Anorg. Allg. Chem. 172, 321343.
Peterson, R. C. and Wang, R. (2006). “Crystal molds on Mars: melting of a possible new mineral species to create Martian chaotic terrain,” Geology 34, 957960.
Peterson, R. C., Nelson, W., Madu, B., and Shurvell, H. F. (2007). “Meridianiite: a new mineral species observed on Earth and predicted to exist on Mars,” Am. Min. 92, 17561759.
Putz, H. and Brandenburg, K. (2006). Diamond – Crystal and Molecular Structure Visualization (Crystal Impact – GbR, Bonn, Germany)
Röttger, K., Endriss, A., Ihringer, J., Doyle, S., and Kuhs, W. F. (1994). “Lattice constants and thermal expansion of H2O and D2O ice Ih between 10 and 265 K,” Acta Crystallogr., Sect. B 50, 644648.
Smith, G. S. and Snyder, R. L. (1979). “ F N : a criterion for rating powder diffraction patterns and evaluating the reliability of powder-pattern indexing,” J. Appl. Cryst. 12, 6065.
Snyman, H. C., and Pistorius, C. W. F. T. (1964). “Crystallographic data for NiSeO4 6H2O and MgSeO4 6H2O,” Z. Kristallogr. 119, 465467.
Stoilova, D. and Koleva, V. (1995). “X-ray diffraction study on MgSeO4·6H2O at elevated temperatures,” Cryst. Res. Tech. 30, 547551.
Toby, B. H. (2001). “ EXPGUI, a graphical user interface for GSAS ,” J. Appl. Cryst. 34, 210213.
Toby, B. H. (2003). “CIF applications. XII. Inspecting Rietveld fits from pdCIF: pdCIFplot ,” J. Appl. Cryst. 36, 12851287.
Weil, M. and Bonneau, B. (2014). “Crystal structures of Na2SeO4·1.5H2O and Na2SeO4·10H2O,” Acta Cryst. Sect. E 70, 5457.
Wood, I. G., Hughes, N., Browning, F., and Fortes, A. D. (2012). “A compact transportable, thermoelectrically-cooled cold stage for reflection geometry X-ray powder diffraction,” J. Appl. Crystallogr. 45, 608610.


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