X-RAY ABSORPTION NEAR-EDGE EDGE STRUCTURE SPECTROSCOPY FOR DIAGNOSTICS OF ATOMIC AND ELECTRONIC STRUCTURE OF GEOLOGICAL MATERIALS

Size: px

Start display at page:

Download "X-RAY ABSORPTION NEAR-EDGE EDGE STRUCTURE SPECTROSCOPY FOR DIAGNOSTICS OF ATOMIC AND ELECTRONIC STRUCTURE OF GEOLOGICAL MATERIALS"

Bartholomew Turner
6 years ago
Views:

1 X-RAY ABSORPTION NEAR-EDGE EDGE STRUCTURE SPECTROSCOPY FOR DIAGNOSTICS OF ATOMIC AND ELECTRONIC STRUCTURE OF GEOLOGICAL MATERIALS Antonina N. Kravtsova XX Russian Synchrotron Radiation Conference SR , 7-10 July, 2014, Novosibirsk 1

2 Southern Federal University Rostov-on on-don over 30 faculties 11 research institutes over students over employers 2

atomic distribution Information 3D atomic structure (interatomic

3 X-ray absorption near-edge edge structure (XANES) spectroscopy Advantages investigation of materials without long-rang order in atomic distribution Information 3D atomic structure (interatomic distances and bonding angles), electronic structure, 3 oxidation state of atoms.

4 Obtaining of structural information from XANES spectra Experiment Theoretical analysis Local 3D structure Поглощение ( отн.ед) Эксперимент Энергия ( эв) 4

approximation for the potential shape); FDMNES (full-potential finite difference method); ADF (quantum-mechanical calculations within

5 Methods of theoretical investigation G4XANES (multiple scattering theory, non-self-consistent potential calculation, muffin-tin approximation for the potential shape); FEFF9 (full multiple scattering method, self-consistent potential calculation, muffin-tin approximation for the potential shape); FDMNES (full-potential finite difference method); ADF (quantum-mechanical calculations within the density functional chemistry); FitIt 2.0 (refinement of structural parameters on the basis of multiple interpolation of XANES spectra). 5

3D structure refined by quantitative XANES analysis Multidimensional interpolation of XANES spectra as function of structural parameters. FitIt software Smolentsev G., Soldatov A.V., J.

6 3D structure refined by quantitative XANES analysis Multidimensional interpolation of XANES spectra as function of structural parameters. FitIt software Smolentsev G., Soldatov A.V., J. Synchrotron Rad. 13 (2006) Smolentsev G., Soldatov A.V., Feiters M.C., Phys. Rev. B 75 (2007) Smolentsev G., Soldatov A.V., Chen L.X., J. Phys. Chem A 112 (2008)

7 sulfur geological materials Objects of investigations - CaS, MgS, MnS sulfides with NaCl-type structure - FeS, CoS, NiS sulfides with NiAs-type structure - Mg 1-x Fe x S solid solution TiO 2 (rutile and anatase), oxidized titanium in nanosclae state Ti-containing minerals - forsterite, - clinogumite, - ilmenite, - zircon, - hibonite garnet from Taman peninsula deposits REE-containing (REE = Eu, Sm, Yb, Ce) silicates 7

8 Sulfur geological materials R 2 * E=const - Natoli s rule S K-XANES 5 5 A B C Normalized absorption Experiment (MnS) Experiment (CaS) Experiment (MgS) Theory (MnS) Theory (CaS) Theory (MgS) Energy (ev) Theory (FeS) (a) (b) Comparison of the experimental and theoretical S K-edge XANES spectra in MgS, CaS, MnS with cubic NaCl-type structure (panel а) and FeS, CoS, NiS with hexagonal NiAs-type structure (panel b). Normalized absorption Energy (ev) Exper. (CoS) Exper. (NiS) Exper. (FeS) Theory (CoS) Theory (NiS) 8

9 Density of states (DOS) of NiS 5 A B Ni d-dos DOS (rel.units) S p-dos (x 2) Energy (ev) Partial S p-dos and Ni d-dos of nickel sulfide. The calculations are for a cluster size of 170 atoms. S p-dos is multiplied by factor 2. Origin of the energy scale corresponds to the zero of muffin-tin energy. Energy of Fermi level is ev. A.N. Kravtsova, I.E. Stekhin, A.V. Soldatov, X.Liu, M.E. Fleet. Physica Status Solidi (b) 234, No. 2 (2002) R4-R5. S.P. Farrel, M.E. Fleet, I.E. Stekhin, A. Kravtsova, A.V. Soldatov. American Mineralogist 87 (2002) A.V. Soldatov, A.N. Kravtsova, M.E. Fleet, S.L. Harmer. Journal of Physics: Condensed Matter 16 (2004) A.N. Kravtsova, I.E. Stekhin, A.V. Soldatov, X. Liu, M.E. Fleet. Physical Review B 69 (2004) A.N. Kravtsova, I.E. Stekhin, A.V. Soldatov, M.E. Fleet, S.L. Harmer. Journal of Electron Spectroscopy and Related Phenomena (2005)

units) Ti K-XANES in TiO 2 (anatase) B 1 A 2 A A 3 1 B C 2 C C1 3 FDM FDM, MT FMS, MT (FDMNES) FMS, MT (FEFF8.

10 Influence of the muffin-tin approximation on the simulation of the Ti K-XANES K in TiO 2 XANES (rel.units) A 1 A 2 rutile A 3 B Ti K-XANES in TiO 2 (rutile) B 1 B 2 C Energy (ev) D anatase E Experiment FDM (FDMNES) FMS, MT (FEFF8.4) XANES (rel.units) Ti K-XANES in TiO 2 (anatase) B 1 A 2 A A 3 1 B C 2 C C1 3 FDM FDM, MT FMS, MT (FDMNES) FMS, MT (FEFF8.4) D E Energy (ev) G Experiment FMS full multiple scattering theory calculation FDM finite difference method calculation MT calculation within the muffin-tin approximation for the shape of the crystal potential 10 A.N. Kravtsova, A.V. Soldatov et al. // Physica B V P

Berry // Journal of Physics: Conference Series. 2009. - V. 190. - 012181. N.D. Tailby, A.M. Walker, A.J. Berry et al.

11 Mg 2 SiO 4 Atomic and electronic structure of Ti-bearing forsterite Titanium atom substitutes silicon atom Titanium atom substitutes magnesium atom I.S. Rodina, A.N. Kravtsova, M.A. Soldatov, A.V. Soldatov, A.J. Berry // Journal of Physics: Conference Series V N.D. Tailby, A.M. Walker, A.J. Berry et al. // Geochimica et Cosmochimica Acta V. 75. P I.S. Rodina, А.N. Kravtsova, А.V. Soldatov, А.J. Berry // Optics and Spectroscopy V. 111, 6. P

12 Ti K-XANES in forsterite Normalized absorption 2,0 1,5 1,0 0,5 A B 2 B 1 C 0, D E Energy, ev Experiment titanium atom substitutes silicon atom 2 - titanium atom substitutes magnesium atoms 3-50% of Ti atoms substitute Si atoms and 50% of Ti atoms substitute Mg atoms XANES spectra have been calculated on the basis of full-potential finite difference method using FDMNES program code. 12

13 X-ray spectroscopic identification of garnet from the placer deposits of the Taman peninsula The general formula: A 3 B 2 [SiO 4 ] 3 A Mg 2+, Fe 2+, Mn 2+, Ca 2+,Y 2+ B Al 3+, Fe 3+, Cr 3+, V 3+, Mn 3+, Ti 4+, Zr 4+ End members of the isomorphous series of natural garnets: Almandine Fe 2+ 3 Al 2 [SiO 4 ] 3 Andradite Са 3 Fe 3+ 2 [SiO 4 ] 3 Grossular Ca 3 Al 2 [SiO 4 ] 3 Spessartine Mn 3 Al 2 [SiO 4 ] 3 Pyrope Mg 3 Al 2 [SiO 4 ] 3 Uvarovite Ca 3 Cr 2 [SiO 4 ] 3 13

14 X-ray absorption spectrometer Rigaku R-XAS

15 X-ray fluorescence spectrum of the garnet FeKa Intensity, rel. units ZnKb FeKb ZnKa CuKa MnKb NiKa MnKa SPARK-1-2М 1,4 1,6 1,8 2,0 2,2 l, Å Almandine Fe 2+ 3 Al 2 [SiO 4 ] 3 Andradite Са 3 Fe 3+ 2 [SiO 4 ] 3 15

16 Absorption, rel. units 1,0 0,5 0,0 Test measurements Ti K-XANES in rutile Energy, ev Rigaku R-XAS SLS XANES spectra have been recorded on a laboratory Rigaku R-XAS X-ray absorption spectrometer in a transmission mode. Absorption, rel. units 1,0 0,5 0,0 Fe K-XANES of garnet from the Taman peninsula A 1,5 C B Energy, ev Experiment Theory (almandine) Theory (andradite) I.S. Rodina, А.N. Kravtsova, А.V. Soldatov, G.E. Yalovega, Yu.V. Popov, N.I. Boyko // Optics and Spectroscopy V. 115, 6. P

17 Conclusions 1. Analysis of the S K- and S L 2, 3 -XANES spectra has shown that Natoli s rule (similarity of spectral shape) is satisfied for FeS, NiS, CoS monosulfides and is not satisfied for MgS, CaS, MnS monosulfides due to the significant difference in the electronic configuration of metal atoms. 2. The adequate description of the Ti K-XANES spectra of TiO 2 demands calculations within a full potential (i.e. beyond the muffin-tin approximation) for the crystal potential shape. 3. Comparison of the experimental and theoretical Ti K-XANES spectra has allowed to determine the local atomic structure around titanium atoms in forsterite. It has been established that the model of substitution of silicon atoms by titanium atoms is the most probable structural model of Ti-bearing forsterite. 4. The analysis of the Fe K-XANES spectra indicates that the almandine component is dominant on the composition of the garnet from the recent placer deposit of the Taman peninsula. On the whole, synchrotron-based XANES spectroscopy is an effective method to obtain information on the local atomic and electronic structure of geological materials. 17

18 Acknowledgements To the organizing committee of XX Russian Synchrotron Radiation Conference SR-2014! To the co-authors of research projects: А.V. Soldatov, G.E. Yalovega, I.Е. Stekhin, I.S. Rodina, A.A. Guda, V.L. Mazalova, Yu.V. Popov, N.I. Boyko (Southern Federal University, Rostov-on-Don) A.J. Berry (Australian National University, Canberra, Australia) A.M. Walker (University of Leeds, Leeds, UK) J.A. van Bokhoven, M.W. Tew (Institute for Chemical and Bioengineering, Switzerland) M.E. Fleet (University of Western Ontario, London, Canada) P. Milani, P. Piseri, T. Mazza, G. Bongiorno, M. Coreno, C. Lenardi (Universita degli Studi di Milano, Milano, Italy) V.K. Taroev (A.P. Vinogradov Institute of Geochemistry SB RAS, Irkutsk) To the grant of the Russian Foundation for Basic Research - RFBR

19 Thank you for your attention! 19

ACADEMICIAN LUSEGEN ARMENAK BUGAEV CURRICULUM VITAE

, pp. 43-47 ACADEMICIAN LUSEGEN ARMENAK BUGAEV CURRICULUM VITAE Head of Department of Theoretical and Computational Physics, Physical Faculty of Southern Federal University (former Rostov State University),