Abstract
Neutron diffraction data suitable for Rietveld refinements were collected on a powder sample of synthetic Mg(OH)2 by the Polaris time-of-flight spectrometer (ISIS spallation source, U.K.) at 10-4 7.8(3) and 10.9(6) GPa. The Paris-Edinburgh high-pressure cell with WC anvils was used. Pressure calibration and equation-ofstate results were attained by separate runs with an NaCl internal standard. Interpolation of p(V) data by the fourth-order Birch-Murnaghan e.o.s. yields K 0=41(2) GPa, K′0=4(2) and K″0=1.1(9) GPa-1. The bulk modulus obtained is smaller than previously reported results. Rietveld refinements (R prof =1.45% and 2.02% at 10-4 and 10.9 GPa) show that H lies on the threefold axis (1/3, 2/3, z) up to 10.9 GPa, where a model with H disordered in (x, 2x, z) can be refined. In the latter case, a hydrogen bond with O-H=0.902(7), H..O′=2.026(8) Å and <OHO′=145.9 (7)° is observed. Differences with previous results for deuterated brucite are discussed. The onset of H disorder, and a jump of the c/a ratio vs. pressure at 6–7 GPa, may be related to a second-order phase transition consistent with recently reported Raman spectroscopic results.
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References
Bernal JD, Megaw HD (1935) The function of hydrogen in intermolecular forces. Proc Roy Soc London 151A:384–420
Besson JM, Nelmes RJ, Hamel G, Loveday JS, Weill G, Hull S (1992) Neutron powder diffraction above 10 GPa. Physica B 180–181:907–910
Birch F (1978) Finite strain isotherm and velocities for single-crystal and polycrystalline NaCl at high pressures and 300 K. J Geophys Res 83:1257–1267
Busing WR, Levy HA (1957) Neutron diffraction study of calcium hydroxide. J Chem Phys 26:563–568
Catti M (1992) Physical properties of crystals. In: Giacovazzo C (ed) Fundamentals of crystallography, Chapter 9. Oxford University Press, Oxford
Catti M, Ferraris G, Hull S (1991) Powder neutron diffraction study of brucite and gibbsite and pressure dependence of the structure of Mg(OD)2. XIII European Crystallographic Meeting, Ljubliana-Trieste, 26–30 August 1991, Book of abstracts: 316
Catti M, Ferraris G, Hull S, Pavese A (1994) Powder neutron diffraction study of 2M1 muscovite at room pressure and at 2 GPa. Eur J Mineral 6:171–178
Chiari G, Ferraris G (1982) The water molecule in crystalline hydrates studied by neutron diffraction. Acta Crystallogr B38:2331–2341
D'Arco Ph, Causà M, Roetti C, Silvi B (1993) Periodic Hartree-Fock study of a weakly bonded layer structure: brucite Mg(OH)2. Phys Rev B47:3522–3529
Decker DL (1971) High-pressure equation of state for NaCl, KCl, and CsCl. J Appl Phys 42:3239–3244
Duffy TS, Ahrens TJ, Lange MA (1991) The shock wave equation of state of brucite Mg(OH)2. J Geophys Res 96:14319–14330
Duffy TS, Meade C, Fei Y, Mao HK, Hemley RJ (1994) Highpressure phase transition in brucite Mg(OH)2. Submitted to Am Mineral
Elleman DD, Williams D (1956) Proton positions in brucite crystals. J Chem Phys 25:742–744
Fei Y, Mao HK (1993) Static compression of Mg(OH)2 to 78 GPa at high temperature and constraints on the equation of state of fluid H2O. J Geophys Res 98:11875–11884
Johnson MC, Walker D (1993) Brucite [Mg(OH)2] dehydration and the molar volume of H2O to 15 GPa. Am Mineral 78:271–284
Klug DD, Whalley E (1984) The uncoupled O-H stretch in ice VII. The infrared frequency and integrated intensity up to 189 kbar. J Chem Phys 81:1220–1228
Kruger M, Williams Q, Jeanloz R (1989) Vibrational spectra of Mg(OH)2 and Ca(OH)2 under pressure. J Chem Phys 91:5910–5915
Larson AC, Von Dreele RB (1986) GSAS: General structure analysis system manual. Los Alamos National Laboratory Report LAUR 86–748
Meade C, Jeanloz R (1990) Static compression of Ca(OH)2 at room temperature: observations of amorphization and equation of state measurements to 10.7 GPa. Geophys Res Lett 17:1157–1160
Nelmes RJ, Loveday JS, Wilson RM, Besson JM, Pruzan Ph, Klotz S, Hamel G, Hull S (1993) Neutron diffraction study of the structure of deuterated ice VIII to 10 GPa. Phys Rev Lett 71:1192–1195
Parise JB, Leinenweber K, Weidner DJ, Tan K, Von Dreele RB (1994) Pressure-induced H bonding: neutron diffraction study of brucite, Mg(OD)2, to 9.3 GPa. Am Mineral 79:193–196
Redfern SAT, Wood BJ (1992) Thermal expansion of brucite, Mg(OH)2. Am Mineral 77:1129–1132
Ross CR II, Webb SL (1990) BIRCH, a program for fitting PV data to an Eulerian finite-strain equation of state. J Appl Cryst 23:439–440
Sherman DM (1991) Hartree-Fock band structure, equation of state, and pressure-induced hydrogen bonding in brucite, Mg(OH)2. Am Mineral 76:1769–1772
Zigan F, Rothbauer R (1967) Neutronenbeugungsmessungen am Brucit. N Jahrb Mineral Monatsh: 137–143
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Catti, M., Ferraris, G., Hull, S. et al. Static compression and H disorder in brucite, Mg(OH)2, to 11 GPa: a powder neutron diffraction study. Phys Chem Minerals 22, 200–206 (1995). https://doi.org/10.1007/BF00202300
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DOI: https://doi.org/10.1007/BF00202300