Phase transformations in minerals

1. Phase transformations in minerals (including displacive transformations, order-disorder transformations, and exsolution), with particular reference to the evolution of the microstructure, as studied by transmission electron microscopy (incorporated in the Interdisciplinary Centre for Electron Microscopy and Microanalysis) as well as the characterization of structural changes by diffraction and spectroscopic methods. Structural changes as a function of temperature in ionic conductors are being studied as part of the Special Research Area (Sonderforschungsbereich SFB 458 : Ionenbewegung in Materialien mit ungeordneten Strukturen - vom Elementarschritt zum makroskopischen Transport). Computational methods and statistical thermodynamic modelling are being used to determine the thermodynamic properties of solid solutions with different degrees of short and long range order. Application of spin models and the calculation of phase diagrams in aluminosilicate systems is part of the special research area (Schwerpunkt Programme) "Structural Gradients in Crystals"

Drittmittelgeber:

Deutsche Forschungsgemeinschaft, Alexander-von-Humboldt Stiftung, Europäische Gemeinschaft, VGB Stiftung, BMBF

Beteiligte Wissenschaftler:

Dr. Michael Enders, Dr. Hans Freiheit, Dr. Ute Golla, Dr. Richard Harrison, Dr. Hong-Chao Liu, Prof. Andrew Putnis

Veröffentlichungen:

Harrison R.J. and Putnis A.: The Magnetic Properties and Crystal Chemistry of Oxide Spinel Solid Solutions. Surveys in Geophysics 19, 461-520 (1999)

Grguric B.A. and Putnis A.: Rapid exsolution behaviour in the bornite-digenite series and implications for natural ore assemblages. Mineralogical Magazine 63, 1-14 (1999)

Redfern S.A.T., Harrison R.J., O'Neill H.St.C. and Wood D.R.R.: Thermodynamics and kinetics of cation ordering in MgAl2O4 spinel up to 1600oC from in situ neutron diffraction. American Mineralogist 84, 299-310 (1999)

Vinograd V and Putnis A.: The description of Al,Si ordering in aluminosilicates using the Cluster Variation Method. American Mineralogist 84, 311-324 (1999)

Harrison, R.J., Dove, M.T., Knight, K.S., and Putnis, A.: In situ neutron diffraction study of non-convergent ordering in the spinel solid solution (Fe3O4)1-x(MgAl2O4)x: kinetics and equilibrium ordering. American Mineralogist 84, 555-563 (1999)

Harrison R.J. and Putnis A.: Determination of the mechanism of cation ordering in magnesioferrite (MgFe2O4) from the time- and temperature-dependence of magnetic susceptibility. Physics and Chemistry of Minerals 26, 322-332 (1999)

Putnis A. and Vinograd V.: Principles of solid state NMR spectroscopy and applications to determining local order in minerals. In: Microscopic Properties and Processes in Minerals . NATO ASI Series (Eds.: Wright K. and Catlow C.R.A.) Reidel (1999)

Hochella M.F. Jr., Moore J.N., Golla U. and Putnis A.: A TEM study of samples from acid mine drainage systems: Metal-mineral association with implications for transport. Geochim. Cosmochim. Acta. 63, 3395-3406 (1999)

Harrison R.J., Redfern S.A.T. and Smith R.I.: In-situ study of the R-3 to R-3c phase transition in the ilmenite-hematite solid solution using time-of-flight neutron powder diffraction" American Mineralogist 85, 194-205 (2000)

Bismayer U., Matthes D., Bosbach D., Putnis A., Van Tendeloo G., Novak J. and Salje E.K.H.: Ferroelastic orientation states and domain walls in lead phosphate type crystals. Mineral. Mag. 64, 233-239 (2000)

Grguric B.A., Harrison R. and Putnis A.: A revised phase diagram for the bornite-digenite join from in situ neutron diffraction and DSC experiments. Mineral. Mag. 64, 299-317 (2000)

Enders M., Spiegel M., Albrecht J. and Putnis A.: Mineralogical problems in advanced power systems: The contribution of slag and gaseous species to the fly ash. Europ. Journ. Mineral. 12, 639-650 (2000)

Bismayer U., Mathes D., Aroyo M., Bosbach D., Putnis A., Van Tendeloo G. and Güttler D.: Ferroelastic domains in lead phosphate-arsenate: an AFM, X-ray diffraction, TEM and Raman study. Phase Transitions. 71, 243-270 (2000)

Enders M., Putnis A. and Albrecht J.: Temperature-dependent fractionation of particulate matter and sulfates from a hot flue gas in pressurized pulverized coal combustion (PPPC). Energy and Fuels 14, 806-815 (2000)

Enders M., Willenborg W., Albrecht, J. and Putnis A.: Alkali retention in hot slag under controlled oxidising gas atmospheres (air-CO2). Fuel Processing Technology 68, 57-73 (2000)

Harrison R., Becker U. and Redfern S.A.T.: Thermodynamics of the R3 to R3c phase transition in the ilmenite-hematite solid solution. American Mineralogist 85, 1694-1705 (2000)

Vinograd V.L., Becker U. and Putnis A.: Maximization of cluster entropies via an irreversible algorithm : Application to the cluster variation method. In: Properties of complex inorganic solids. Vol.II. Meike A., Gonis A., Turchi P.E.A. and Rajam K. (eds) pp. 249-260 Kluwer Academic/Plenum Publishers, Dordecht, The Netherlands (2000)