Fe2+-O and Mn2+-O bonding and Fe2+- and Mn2+-vibrational properties in synthetic almandine-spessartine solid solutions: an X-ray absorption fine structure study

X-ray absorption fine structure (XAFS) measurements at the Fe and Mn K-edges were undertaken to investigate the Fe2+-O and Mn2+-O bonding, and Fe2+- and Mn2+-vibrational properties for a series of synthetic almandine-spessartine, (Fe,Mn)(3)Al2Si3O12, garnet solid solutions. The two end members almandine, Fe3Al2Si3O12, and spessartine, Mn3Al2Si3O12, and three solid solutions of composition Alm75Sps25, Alm50Sps50 and Alm25Sps75 were studied at different temperatures between 77 K and 423 K. The spectra show that the state of alternating bonds provides an appropriate description for the two crystallographic ally independent X-O(1) and X-O(2) bonds in the solid solution. An exchange of X-site cations in garnet is associated with measurable structural relaxation. The compositional and temperature dependence of the XAFS Debye-Waller factors for Fe2+ and Mn2+ in the plane of the X-O(1) and the X-O(2) bonds were also determined. Their values in the plane of the X-O(2) bonds are greater compared to those for X-O(1) and they do not vary greatly as a function of garnet composition. In the case of end-member spessartine, the XAFS Debye-Waller factors for Mn2+ are compared to the Debye-Waller factors measured from single-crystal X-ray diffraction. An analysis shows correlation in the atomic displacements along the shorter Mn-O(1) bond.

[1]  M. Grodzicki,et al.  The crystal chemistry and FeII–site properties of aluminosilicate garnet solid solutions as revealed by Mössbauer spectroscopy and electronic structure calculations , 2003 .

[2]  W. Westrenen,et al.  Trace element incorporation into pyrope–grossular solid solutions: an atomistic simulation study , 2003 .

[3]  S. Quartieri,et al.  Characterization of trace Nd and Ce site preference and coordination in natural melanites: a combined X-ray diffraction and high-energy XAFS study , 2002 .

[4]  V. Heine,et al.  Scaling of thermodynamic mixing properties in garnet solid solutions , 2001 .

[5]  M. Dove,et al.  Simulation studies on the pyrope-grossular garnet solid solution , 2000 .

[6]  S. Quartieri,et al.  XAFS characterization of the structural site of Yb in synthetic pyrope and grossular garnets. II: XANES full multiple scattering calculations at the Yb LI- and LIII-edges , 1999 .

[7]  C. Geiger.  Thermodynamics of (Fe2+, Mn2+, Mg, Ca)3− Al2Si3O12 garnet: a review and analysis , 1999 .

[8]  P. P. Lottici,et al.  XAFS characterization of the structural site of Yb in synthetic pyrope and grossular garnets , 1999 .

[9]  T. Armbruster,et al.  The crystal structure of a garnet solid solution (Ca0.9Mg0.1)3Al2[SiO4]3 at 295 K and 100 K: Local site behavior – dynamic and static disorder , 1999 .

[10]  B. A. Kolesov,et al.  Raman spectra of silicate garnets , 1998 .

[11]  T. Armbruster,et al.  Mn3Al2Si3O12 spessartine and Ca3Al2Si3O12 grossular garnet: Structural dynamic and thermodynamic properties , 1997 .

[12]  A. Feenstra,et al.  Molar volumes of mixing of almandine-pyrope and almandine-spessartine garnets and the crystal chemistry and thermodynamic-mixing properties of the aluminosilicate garnets , 1997 .

[13]  P. P. Lottici,et al.  A temperature dependent X-ray Absorption Fine Structure study of dynamic X-site disorder in almandine: a comparison to diffraction data , 1997 .

[14]  A. Marcelli,et al.  Comparison of XAS Spectra at the Al K-Edge in Garnets to Multiple-Scattering Calculations , 1997 .

[15]  Wu,et al.  Effects of higher-coordination shells in garnets detected by x-ray-absorption spectroscopy at the Al K edge. , 1996, Physical review. B, Condensed matter.

[16]  L. Galoisy.  Local versus average structure around cations in minerals from spectroscopic and diffraction measurements , 1996 .

[17]  F. d’Acapito,et al.  X-ray Optics of a Dynamical Sagittal-Focusing Monochromator on the GILDA Beamline at the ESRF. , 1996, Journal of synchrotron radiation.

[18]  M. Leona,et al.  Non-ideal solid-solution in garnet: crystal-structure evidence and modelling , 1995 .

[19]  M. Merli,et al.  Local structural environment of calcium in garnets: A combined structure-refinement and XANES investigation , 1995 .

[20]  G. Rossman,et al.  Crystal field stabilization energies of almandine-pyrope and almandine-spessartine garnets determined by FTIR near infrared measurements , 1994 .

[21]  J. Ganguly,et al.  Syntheses, volume, and structural changes of garnets in the pyrope-grossular join : implications for stability and mixing properties , 1993 .

[22]  P. P. Lottici,et al.  X-ray absorption study at the Fe K-edge of garnets from the Ivrea-Verbano zone , 1993, Mineralogical Magazine.

[23]  T. Armbruster,et al.  A combined temperature dependent57Fe Mössbauer and single crystal X-ray diffraction study of synthetic almandine: evidence for the Gol'danskii-Karyagin effect , 1992 .

[24]  T. Armbruster,et al.  Single-crystal X-ray structure study of synthetic pyrope almandine garnets at 100 and 293 K , 1992 .

[25]  J. Rehr,et al.  Ab initio curved-wave x-ray-absorption fine structure. , 1991, Physical review. B, Condensed matter.

[26]  John J. Rehr,et al.  Theoretical X-ray Absorption Fine Structure Standards , 1991 .

[27]  A. Chopelas,et al.  Vibrational spectroscopy of end-member silicate garnets , 1991 .

[28]  A. Zunger,et al.  Bond lengths around isovalent impurities and in semiconductor solid solutions , 1984 .

[29]  Grant Bunker,et al.  Application of the ratio method of EXAFS analysis to disordered systems , 1983 .

[30]  P. Eisenberger,et al.  Extended x-ray absorption fine structure—its strengths and limitations as a structural tool , 1981 .

[31]  R. Greegor,et al.  Extended x-ray absorption fine structure determination of thermal disorder in Cu: Comparison of theory and experiment , 1979 .

[32]  J. Rehr,et al.  Extended x-ray absorption fine structure Debye-Waller factors. I. Monatomic crystals , 1979 .

[33]  G. Beni,et al.  Temperature and polarization dependence of extended x-ray absorption fine-structure spectra , 1976 .

[34]  H. Liebhafsky.  X-Ray Absorption , 1949 .