High-pressure single-crystal X-ray and powder neutron study of F,OH/OD-chondrodite: Compressibility, structure, and hydrogen bonding

Abstract The crystal structure of a natural F-bearing chondrodite [Mg4.64Fe0.28Mn0.014Ti0.023(Si1.01O4)2F1.16OH0.84; a = 4.7328(1), b = 10.2749(2), c = 7.8756(1) Å, a = 109.065(1)∞; space group P21/b (a unique)] from the Tilly Foster mine (Brewster, New York) and the structure of a deuterated synthetic analogue [Mg5(SiO4)2F1.10OD0.90] were refined at high pressure using single-crystal X-ray and time-of-flight neutron powder diffraction data, respectively. The isothermal equation of state was determined from single-crystal high-precision X-ray diffraction measurements of unit-cell parameters as a function of pressure up to 9.63(1) GPa. A third-order Birch-Murnaghan equation-of-state fit to pressurevolume data results in V0 = 362.00(2) Å3, K0,T = 117.0(4) GPa and KT' = 5.6(1). The larger value of K0,T relative to that determined for the OH end-member confirms that F makes the chondrodite structure less compressible. The axial compressibilities behave anisotropically with fitted parameters a0 = 4.73282(9) Å, K(a)0 = 458(3) GPa, and K(a)' = 28.9(9); b0 = 10.2759(3) Å, K(b)0 = 298(1) GPa, and K(b)' = 13.4(4); c0 = 7.8759(2) Å, K(c)0 = 316(2) GPa, and K(c)' = 16.7(5). X-ray structural investigations at 0.0001, 4.952(7), and 9.550(7) GPa in a diamond-anvil cell reveal a complex compression mechanism. The greatest changes with pressure occur in the M2 octahedra, which are located at the flexion points of the octahedral chain. These octahedra have the longest bonds at ambient conditions due to cation-cation repulsion, which displaces the cation from the centroid of the octahedron. The application of pressure overcomes the effect of cation-cation repulsion inducing a strong bond-length compression. The neutron powder data were collected at 0.0001, 1.26(1), 2.89(2), 3.87(1), 5.27(2), and 7.04(2) GPa in the Paris-Edinburgh cell using a new gasket design and a fluid pressure medium. Changes in the O-D···O/F hydrogen bond geometry with pressure can be interpreted in terms of a rotation of the OD vector and a reduction in the degree of static disorder associated with the hydrogen bond acceptor/donor site. These new crystallographic data are discussed in terms of corresponding spectroscopic measurements reported recently in the literature

[1]  W. G. Marshall,et al.  Attainment of near-hydrostatic compression conditions using the Paris–Edinburgh cell , 2002 .

[2]  M. Kunz,et al.  Temperature-dependent single-crystal neutron diffraction study of natural chondrodite and clinohumites , 2001 .

[3]  N. Ross,et al.  Compression of synthetic hydroxylclinohumite [Mg9Si4O16(OH)2] and hydroxylchondrodite [Mg5Si2O8(OH)2] , 2001 .

[4]  V. Trommsdorff,et al.  Genesis of ilmenite rods and palisades along humite-type defects in olivine from Alpe Arami , 2001 .

[5]  R. Stalder,et al.  Phase relations of a serpentine composition between 5 and 14 GPa: significance of clinohumite and phase E as water carriers into the transition zone , 2001, Contributions to Mineralogy and Petrology.

[6]  J. Loveday,et al.  Hydrogen bonding interactions in phase A [Mg7Si2O8(OH)6] at ambient and high pressure , 2000 .

[7]  S. Sinogeikin,et al.  Single-crystal elastic properties of chondrodite: implications for water in the upper mantle , 1999 .

[8]  A. Hofmeister,et al.  Vibrational spectra of dense, hydrous magnesium silicates at high pressure: Importance of the hydrogen bond angle , 1999 .

[9]  Chung-Cherng Lin,et al.  High-pressure Raman spectroscopic study of chondrodite , 1999 .

[10]  R. Angel,et al.  The Use of Quartz as an Internal Pressure Standard in High-Pressure Crystallography , 1997 .

[11]  Greg Hirth,et al.  Water in the oceanic upper mantle: implications for rheology , 1996 .

[12]  Q. Williams,et al.  Infrared spectra of phase B at high pressures: Hydroxyl bonding under compression , 1996 .

[13]  S. Hull,et al.  Static compression and H disorder in brucite, Mg(OH)2, to 11 GPa: a powder neutron diffraction study , 1995 .

[14]  J. Ganguly,et al.  Quartz-coesite transition revisited: Reversed experimental determination at 500–1200 °C and retrieved thermochemical properties , 1995 .

[15]  G. Rossman,et al.  Enhanced H and F incorporation in borian olivine , 1994 .

[16]  A. Hofmeister,et al.  High-pressure IR spectra of lattice modes and OH vibrations in Fe-bearing wadsleyite , 1994 .

[17]  E. Knittle,et al.  Static compression of chondrodite: Implications for water in the upper mantle , 1994 .

[18]  D. Giardini,et al.  Isolated deep earthquakes and the fate of subduction in the mantle , 1994 .

[19]  J. Loveday,et al.  Neutron powder diffraction above 10 GPa , 1992 .

[20]  R. F. Dymek,et al.  Titanian chondrodite- and titanian clinohumite-bearing metadunite from the 3800 Ma Isua supracrustal belt, West Greenland; chemistry, petrology and origin , 1988 .

[21]  G. Rossman,et al.  The natural occurrence of hydroxide in olivine , 1987 .

[22]  A. Putnis,et al.  Planar OH-bearing defects in mantle olivine , 1987, Nature.

[23]  D. Lindsley,et al.  Stability of titanian clinohumite: Experiments and thermodynamic analysis , 1980 .

[24]  A. Boettcher,et al.  Reinvestigation and application of olivine-quartz-orthopyroxene barometry , 1980 .

[25]  P. Ribbe.  Titanium, fluorine, and hydroxyl in the humite minerals , 1979 .

[26]  L. Finger,et al.  Diffracted beam crystal centering and its application to high‐pressure crystallography , 1979 .

[27]  E. Gabe,et al.  The analysis of single‐crystal Bragg reflections from profile measurements , 1978 .

[28]  Larry W. Finger,et al.  A revised method of operation of the single-crystal diamond cell and refinement of the structure of NaCl at 32 kbar , 1978 .

[29]  Robert M. Hazen,et al.  Effects of temperature and pressure on the crystal structure of forsterite , 1976 .

[30]  G. V. Gibbs,et al.  Quadratic Elongation: A Quantitative Measure of Distortion in Coordination Polyhedra , 1971, Science.

[31]  A. Chodos,et al.  Titanoclinohumite: A possible mineralogical site for water in the upper mantle , 1970 .

[32]  H. Rietveld.  A profile refinement method for nuclear and magnetic structures , 1969 .

[33]  C. Burnham.  Computation of absorption corrections, and the significance of end effect , 1966 .

[34]  W. G. Marshall,et al.  O-D…O bond geometry in OD-chondrodite , 2001 .

[35]  K. Leinenweber,et al.  Pressure-induced H bonding: Neutron diffraction study of brucite, Mg(OD)2, to 9.3 GPa P = 9.3 GPa , 1994 .

[36]  R. Blessing.  Data Reduction and Error Analysis for Accurate Single Crystal Diffraction Intensities , 1987 .

[37]  Yasuhiro Kudoh,et al.  The crystal structure of forsterite Mg2SiO4 under high pressure up to 149 kb , 1985 .

[38]  G. A. Jeffrey,et al.  A survey of O-H⋯O hydrogen bond geometries determined by neutron diffraction , 1981 .

[39]  C. Duffy,et al.  Phase equilibria in the system MgO-MgF2-SiO2-H2O , 1977 .

[40]  K. Aoki.  Titanochondrodite and titanoclinohumite derived from the upper mantle in the Buell Park kimberlite, Arizona, USA , 1976 .

[41]  L. Finger.  A system of Fortran IV computer programs for crystal structure computations , 1975 .