Multi-spectroscopic study of Fe(II) in silicate glasses: Implications for the coordination environment of Fe(II) in silicate melts

The coordination environment of Fe(II) has been examined in seven anhydrous ferrosilicate glasses at 298 K and 1 bar using 57Fe Mossbauer, Fe K-edge X-ray near edge structure (XANES), and extended X-ray absorption fine structure (EXAFS), UV-Vis-NIR, and magnetic circular dichroism (MCD) spectroscopies. Glasses of the following compositions were synthesized from oxide melts (abbreviation and nonbridging oxygen:tetrahedral cation ratio (NBO/T) in parentheses): Li2FeSi3O8 (LI2: 1.33), Rb2FeSi3O8 (RB2: 1.33), Nal.08Fel.l7Si3.l3O8 (NAl: 1.09), Nal.46Ca0.24Fel.08Si2.97O8 (NC6: 1.38), Nal.09Ca0.51Fe0.72Si3.10O8 (NC2: 1.15), Na0.99Ca0.92Fe0.24 Si3.17O8 (NCl: 1.04), and Na0.29Mg0.53Ca0.52Fe0.56Al0.91Si2.44O8 (BAS: 1.05). Mossbauer, XANES, and EXAFS information suggests that iron is dominantly ferrous in all glasses (<10 atom% Fe(III)) with an average first-neighbor Fe(II) coordination varying from ∼ 4 to 5.2 (±0.2) oxygens. The UV-Vis-NIR spectrum of each sample exhibits intense absorption centered near 8100–9200 cm−1 and weak absorption near 5000 cm−l, which cannot be assigned unambiguously. The MCD spectrum of NC6 glass, which is the first such measurement on a silicate glass, shows three transitions at ∼8500 cm−1, ∼6700 cm−1, and ∼4500 cm−1. The behavior of these MCD bands as a function of temperature (1.6 K to 300 K) and magnetic field strength (1 T to 7 T) indicates that they most likely arise from three distinct Fe(II) sites with different ground states, two of which are 5-coordinated and one of which is 4-coordinated by oxygens. The combined results suggest that Fe(II) predominantly occupies 5- and 4-coordinated sites in each glass, with the ratios differing for the different compositions. Small amounts of 6-coordinated Fe(II) are possible as well, but primarily in the more basic glass compositions such as BAS. The substitution of Li(I) for Rb(I) in the M2FeSi3O8 base glass composition causes a weakening of the average Fe(II)-O bond, as indicated by the longer Fe(II)-O distance in the latter. The basalt composition glass was found to have the largest Fe(II) sites relative to those in the other glasses in this study. A bond valence model that helps predict the coordination number of Fe(II) in silicate glasses is proposed. The structural information extrapolated to Fe(II)-bearing melts is parameterized using bond valence theory, which helps to rationalize the melt-crystal partitioning behavior of ferrous iron in natural and synthetic melt-crystal systems.

[1]  D. Dingwell.  Relaxation in silicate melts; some applications , 1995 .

[2]  E. Takahashi.  Partitioning of Ni2+, Co2+, Fe2+, Mn2+ and Mg2+ between olivine and silicate melts: compositional dependence of partition coefficient , 1978 .

[3]  K. Hodgson,et al.  A Multiplet Analysis of Fe K-Edge 1s → 3d Pre-Edge Features of Iron Complexes , 1997 .

[4]  J. Delaye,et al.  Environment of ferrous iron in CaFeSi2O6 glass; contributions of EXAFS and molecular dynamics , 2000 .

[5]  G. Rossman,et al.  Spectroscopic standard for tetrahedrally coordinated ferric iron: γ LiAlO2:Fe3+ , 1983 .

[6]  P. Petit,et al.  Transition elements in water-bearing silicate glasses/melts. part I. a high-resolution and anharmonic analysis of Ni coordination environments in crystals, glasses, and melts , 2001 .

[7]  M. Arrio,et al.  High-resolution XANES spectra of iron in minerals and glasses: structural information from the pre-edge region , 2001 .

[8]  W. Fyfe,et al.  The coordination number of ferrous ions in silicate glasses , 1972 .

[9]  R. Dunlap,et al.  A Mössbauer effect investigation of correlated hyperfine parameters in natural glasses (tektites) , 1998 .

[10]  R. Greegor,et al.  Measurement of soft x-ray absorption spectra with a fluorescent ion chamber detector. Technical report , 1984 .

[11]  F. Farges,et al.  Chapter 9. X-RAY SCATTERING AND X-RAY SPECTROSCOPY STUDIES OF SILICATE MELTS , 1995 .

[12]  F. Farges,et al.  STRUCTURAL ENVIRONMENTS OF INCOMPATIBLE ELEMENTS IN SILICATE GLASS/MELT SYSTEMS. II: UIV, UV, AND UVI , 1992 .

[13]  J. Rehr,et al.  Coordination chemistry of Ti(IV) in silicate glasses and melts: II. Glasses at ambient temperature and pressure , 1996 .

[14]  D. Dingwell,et al.  Relaxation in silicate melts , 1990 .

[15]  F. Farges.  Does ZrF “complexation” occur in magmas? , 1996 .

[16]  Gerald V. Gibbs,et al.  The Crystal Chemistry of the Silicate Garnets , 1971 .

[17]  C. Brouder,et al.  Calculation of multipole transitions at the Fe K pre-edge through p-d hybridization in the Ligand Field Multiplet model , 2000 .

[18]  M. Dyar.  A review of Moessbauer data on inorganic glasses; the effects of composition on iron valency and coordination , 1985 .

[19]  G. Rossman,et al.  Spectroscopic standards for four- and fivefold-coordinated Fe2+ in oxygen-based minerals , 2001 .

[20]  M. Apted,et al.  X-ray K-edge absorption spectra of Fe minerals and model compounds: Near-edge structure , 1983 .

[21]  G. Waychunas,et al.  Structural transformation in Ni-bearing Na2Si2O5 glass and melt , 1994 .

[22]  J. Fulton,et al.  A Transition in the Ni2+ Complex Structure from Six- to Four-Coordinate upon Formation of Ion Pair Species in Supercritical Water: An X-ray Absorption Fine Structure, Near-Infrared, and Molecular Dynamics Study , 1999 .

[23]  R. Burns.  Thermodynamic data from crystal field spectra , 1985 .

[24]  E. Neumann,et al.  Redox equilibria and the structural states of ferric and ferrous iron in melts in the system CaO-MgO-Al 2 O 3 -SiO 2 -Fe-O; relationships between redox equilibria, melt structure and liquidus phase equilibria , 1985 .

[25]  M. Apted,et al.  X-ray K-edge absorption spectra of Fe minerals and model compounds: II. EXAFS , 1986 .

[26]  J. Tangeman,et al.  The effect of Al3+, Fe3+, and Ti4+ on the configurational heat capacities of sodium silicate liquids , 1998 .

[27]  S. Heald,et al.  New experimental developments for in situ XAFS studies of chemical reactions under hydrothermal conditions , 2000 .

[28]  A. Simionovici,et al.  Iron oxidation states in silicate glass fragments and glass inclusions with a XANES micro-probe , 2001 .

[29]  B. Mysen,et al.  The Structure of Silicate Melts: Implications for Chemical and Physical Properties of Natural Magma (Paper 2R0405) , 1982 .

[30]  M. Olesch,et al.  Mossbauer spectroscopy of grandidierite, (Mg,Fe)Al 3 SiO 9 , 1977 .

[31]  I. D. Brown,et al.  Bond‐valence parameters obtained from a systematic analysis of the Inorganic Crystal Structure Database , 1985 .

[32]  F. Farges.  Structural environment around Th4+ in silicate glasses: Implications for the geochemistry of incompatible Me4+ elements , 1991 .

[33]  W. Fyfe,et al.  Site of Preference Energy and Selective Uptake of Transition-Metal Ions from a Magma , 1964, Science.

[34]  D. Koningsberger,et al.  X-ray absorption : principles, applications, techniques of EXAFS, SEXAFS and XANES , 1988 .

[35]  K. MacKenzie,et al.  MAS NMR study of pentacoordinated magnesium in grandidierite , 1997 .

[36]  F. Farges,et al.  Coordination chemistry of titanium(IV) in silicate glasses and melts: IV. XANES studies of synthetic and natural volcanic glasses and tektites at ambient temperature and pressure , 1997 .

[37]  D. Goldman,et al.  Spectral study of ferrous iron in CaAlborosilicate glass at room and melt temperatures , 1980 .

[38]  Shiv k. Sharma,et al.  Structure of glasses in the systems Mg2SiO4_Fe2SiO4, Mn2SiO4_Fe2SiO4, Mg2SiO4_CaMgSiO4, and Mn2SiO4_CaMnSiO4 , 1990 .

[39]  R. Morris,et al.  Mineralogy of a natural As-rich hydrous ferric oxide coprecipitate formed by mixing of hydrothermal fluid and seawater: Implications regarding surface complexation and color banding in ferrihydrite deposits , 2001 .

[40]  B. Mysen,et al.  The structural state of iron in oxidized vs. reduced glasses at 1 atm: A57Fe Mössbauer study , 1985 .

[41]  B. Mysen.  THE STRUCTURE OF SILICATE MELTS , 1983 .

[42]  Grimm,et al.  Full correction of the self-absorption in soft-fluorescence extended x-ray-absorption fine structure. , 1992, Physical review. B, Condensed matter.

[43]  J. W. Whittaker,et al.  Spectroscopic studies on ferrous nonheme iron active sites: magnetic circular dichroism of mononuclear iron sites in superoxide dismutase and lipoxygenase , 1988 .

[44]  S. Conradson,et al.  High-Temperature XAS Study of Fe2SiO4 Liquid: Reduced Coordination of Ferrous Iron , 1993, Science.

[45]  B. Mysen.  Relations Between Structure, Redox Equilibria of Iron, and Properties of Magmatic Liquids , 1991 .

[46]  G. Brown,et al.  Polymerization of silicate and aluminate tetrahedra in glasses, melts and aqueous solutions—II. The network modifying effects of Mg2+ , K+, Na+, Li+, H+, OH−, F−, Cl−, H2O, CO2 and H3O+ on silicate polymers , 1980 .

[47]  Z. Wu,et al.  XANES studies of Fe-bearing glasses. , 1999, Journal of synchrotron radiation.

[48]  B. Mysen,et al.  Analysis of Mössbauer spectra of silicate glasses using a two-dimensional Gaussian distribution of hyperfine parameters , 1996 .

[49]  S. Samar Hasnain,et al.  X‐ray absorption fine structure , 2020, Catalysis from A to Z.

[50]  D. Nolet.  Optical absorption and Mössbauer spectra of Fe, Ti silicate glasses , 1980 .

[51]  N. Iwamoto,et al.  EXAFS and X-ray diffraction studies of iron ions in a 0.2(Fe2O3) · 0.8(Na2O · 2SiO2) glass , 1987 .

[52]  M. Wilke,et al.  The oxidation state of iron in silicic melt at 500 MPa water pressure , 2002 .

[53]  B. Mysen,et al.  Viscosity and structure of iron- and aluminum-bearing calcium silicate melts at 1 atm , 1985 .

[54]  L. Pauling.  THE PRINCIPLES DETERMINING THE STRUCTURE OF COMPLEX IONIC CRYSTALS , 1929 .

[55]  B. Mysen,et al.  Redox equilibria, structure, and properties of Fe-bearing aluminosilicate melts; relationships among temperature, composition, and oxygen fugacity in the system Na 2 O-Al 2 O 3 -SiO 2 -Fe-O , 1989 .

[56]  P. Petit,et al.  Oxidation state and coordination of Fe in minerals: An Fe K-XANES spectroscopic study , 2001 .

[57]  J. Widom,et al.  X-ray absorption spectroscopy of iron-tyrosinate proteins , 1984 .

[58]  D. Rancourt.  Mössbauer spectroscopy of minerals , 1994 .

[59]  H. Keppler.  CRYSTAL FIELD SPECTRA AND GEOCHEMISTRY OF TRANSITION METAL IONS IN SILICATE MELTS AND GLASSES , 1992 .

[60]  M. Krause,et al.  Natural widths of atomic K and L levels, Kα X‐ray lines and several KLL Auger lines , 1979 .

[61]  N. N. GREENWOOD,et al.  Mossbauer Spectroscopy , 1966, Nature.

[62]  A. Navrotsky,et al.  Thermochemistry of Charge‐Coupled Substitutions in Silicate Glasses: The Systems Ml/nn+ AlO2‐SiO2 (M = Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Pb) , 1984 .

[63]  H. Keppler,et al.  The speciation of Ni and Co in silicate melts from optical absorption spectra to 1500°C , 1999 .

[64]  K. D. Jayasuriya,et al.  XANES calibrations for the oxidation state of iron in a silicate glass , 2003 .

[65]  R. Dunlap.  An investigation of Fe oxidation states and site distributions in a Tibetan tektite , 1997 .

[66]  F. Farges,et al.  Structural environments of incompatible elements in silicate glass/melt systems: I. Zirconium at trace levels , 1991 .

[67]  Boon K. Teo,et al.  EXAFS: Basic Principles and Data Analysis , 1986 .

[68]  S. Rossano,et al.  57Fe Mössbauer spectroscopy of tektites , 1999 .

[69]  D. Virgo,et al.  Redox equilibria of iron in alkaline earth silicate melts: relationships between melt structure, oxygen fugacity, temperature and properties of iron-bearing silicate liquids , 1984 .

[70]  R. J. Williams.  Deposition of Trace Elements in Basic Magma , 1959 .

[71]  G. Waychunas,et al.  Evidence from X-ray absorption for network-forming Fe2+ in molten alkali silicates , 1988, Nature.

[72]  I. Carmichael,et al.  The compressibility of silicate liquids containing Fe2O3 and the effect of composition, temperature, oxygen fugacity and pressure on their redox states , 1991 .

[73]  R. F. Fudali.  Oxygen fugacities of basaltic and andesitic magmas , 1965 .

[74]  D. Dingwell,et al.  Effect of aluminum on Ti-coordination in silicate glasses: A XANES study , 2000 .

[75]  F. Farges,et al.  Local structure around Fe in Mg0.9Fe0.1SiO3 perovskite: an x-ray absorption spectroscopy study at Fe-K edge , 1994 .

[76]  M. Rutherford,et al.  The effect of dissolved water on the oxidation state of silicic melts , 1996 .

[77]  F. Mani,et al.  Halo-, hydrido- and dinitrogen-complexes of iron(II) with tritertiary phosphines , 1974 .

[78]  A. Navrotsky,et al.  Heat capacities of Fe2O3-bearing silicate liquids , 1992 .

[79]  G. Calas,et al.  Structural environment of nickel in silicate glass/melt systems: Part 1. Spectroscopic determination of coordination states , 1993 .

[80]  G. Cressey,et al.  Geological applications of synchrotron radiation , 1995 .

[81]  M. Rivers,et al.  The ferric-ferrous ratio of natural silicate liquids equilibrated in air , 1983 .

[82]  Shiv k. Sharma,et al.  In situ structural investigation of iron-containing silicate liquids and glasses , 1995 .

[83]  G. Materlik,et al.  On the Multipole Character of the X‐Ray Transitions in the Pre‐Edge Structure of Fe K Absorption Spectra. An Experimental Study , 1988 .

[84]  G. Rossman,et al.  Color in feldspars , 1983 .

[85]  B. Mysen.  Structure and Properties of Silicate Melts , 1988 .

[86]  P. Petit,et al.  Transition elements in water-bearing silicate glasses/melts. Part II. Ni in water-bearing glasses , 2001 .

[87]  M. Ghiorso,et al.  Ferric-ferrous equilibria in natural silicate liquids at 1 bar , 1981 .

[88]  P. Roeder.  Activity of iron and olivine solubility in basaltic liquids , 1974 .

[89]  S. Bajt,et al.  X-ray microprobe analysis of iron oxidation states in silicates and oxides using X-ray absorption near edge structure (XANES) , 1994 .

[90]  H. Keppler,et al.  Pressure-induced coordination changes of transition-metal ions in silicate melts , 1993, Nature.

[91]  T. Tyson,et al.  Iron site geometry in orthopyroxene: Multiple scattering calculations and XANES study , 1994 .

[92]  M. Ciampolini,et al.  Trigonal Bipyramidal Complexes of Bivalent Manganese, Iron, and Zinc with Tris (2-dimethylaminoethyl)amine , 1966 .

[93]  Herta Effenberger,et al.  Crystal structure refinements of magnesite, calcite, rhodochrosite, siderite, smithonite, and dolomite, with discussion of some aspects of the stereochemistry of calcite type carbonates , 1981 .

[94]  G. Rossman,et al.  The spectra of iron in orthopyroxene revisited; the splitting of the ground state , 1977 .

[95]  J. Lipscomb,et al.  Variable-temperature variable-field magnetic circular dichroism studies of the Fe(II) active site in metapyrocatechase : implications for the molecular mechanism of extradiol dioxygenases , 1991 .

[96]  G. Calas,et al.  Spectroscopic evidence for five-coordinated Ni in CaNiSi 2 O 6 glass , 1991 .

[97]  F. Farges,et al.  Bond valence in silicate glasses , 2002 .

[98]  P. Manning,et al.  Optical-absorption and Mossbauer spectral studies of iron and titanium site-populations in vesuvianites , 1975 .

[99]  H. Mao,et al.  Optical spectra and electron paramagnetic resonance of lunar and synthetic glasses: a study of the effects of controlled atmosphere, composition, and temperature. , 1976 .

[100]  F. Hawthorne,et al.  THE CHEMISTRY OF VESUVIANITE , 1992 .

[101]  G. Calas,et al.  Structure of oxide glasses : spectroscopic studies of local order and crystallochemistry. Geochemical implications , 1983 .

[102]  K. Righter,et al.  The effect of dissolved water on the oxidation state of iron in natural silicate liquids , 1995 .