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  • 1
    Electronic Resource
    Electronic Resource
    Subsolidus Phase Relationships in the System Fe2O3–Al2O3–TiO2 between 1000° and 1300°C (2003)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 86 (2003), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Subsolidus phase equilibria in the system Fe2O3–Al2O3–TiO2 were investigated between 1000° and 1300°C. Quenched samples were examined using powder X-ray diffraction and electron probe microanalytical methods. The main features of the phase relations were: (a) the presence of an M3O5 solid solution series between end members Fe2TiO5 and Al2TiO5, (b) a miscibility gap along the Fe2O3–Al2O3 binary, (c) an α-M2O3(ss) ternary solid-solution region based on mutual solubility between Fe2O3, Al2O3, and TiO2, and (d) an extensive three-phase region characterized by the assemblage M3O5+α-M2O3(ss) + Cor(ss). A comparison of results with previously established phase relations for the Fe2O3–Al2O3–TiO2 system shows considerable discrepancy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.2003.tb03405.x
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  • 2
    Electronic Resource
    Electronic Resource
    Fe-Mn partitioning between garnet and ilmenite: experimental calibration and applications (1987)
    Springer
    Contributions to mineralogy and petrology 97 (1987), S. 116-126 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract A new mineralogic geothermometer based on the partitioning of Fe and Mn between garnet and ilmenite has been calibrated by reversal experiments in the P-T range 600–900° C, 2 and 5 kbars and for fO2=QFM. The results constitute a sensitive geothermometer applicable over a broad range of composition and conditions. Garnetilmenite thermometry has advantages relative to existing geothermometers because of its accurate calibration, marked temperature sensitivity and the chemical and structural simplicity of the crystalline solutions involved. Application to natural assemblages reveals that the garnet-ilmenite geothermometer yields temperatures that agree well with other estimates. The reactivity of, and relatively rapid Fe-Mn diffusion in ilmenite may lead to retrograde resetting of high temperature partition values, but these factors may be useful for estimating rock cooling rates. Analysis of the experimental data indicates minor positive deviations from ideality for Fe-Mn garnets and ilmenites. Absolute magnitudes of interaction parameters (W AB) derived from a regression analysis are subject to considerable uncertainty. The partition coefficient is, however, strongly dependent on the difference between solution parameters. These differences are well constrained with a magnitude of W FeMn ilm −W FeMn gar ≃300 cal mol−1. The accuracy and applicability of garnet-ilmenite thermometry will improve with the availability of better thermodynamic data for garnet crystalline solutions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00375219
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  • 3
    Electronic Resource
    Electronic Resource
    Fe-Mn partitioning between garnet and ilmenite: experimental calibration and applications (1987)
    Springer
    Contributions to mineralogy and petrology 97 (1987), S. 539-539 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00375334
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  • 4
    Electronic Resource
    Electronic Resource
    Thermodynamic data from redox reactions at high temperatures. I. An experimental and theoretical assessment of the electrochemical method using stabilized zirconia electrolytes, with revised values for the Fe-“FeO”, Co-CoO, Ni-NiO and Cu-Cu2O oxygen buffers, and new data for the W-WO2 buffer (1993)
    Springer
    Contributions to mineralogy and petrology 114 (1993), S. 296-314 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The accuracy and reliability of high temperature thermodynamic data obtained from oxygen concentration cells with stabilized zirconia (SZ) electrolytes are assessed. The experimental apparatus and methods needed to obtain precise results are described. We then test the apparatus, firstly on symmetrical cells of the type: $$Pt, M + M_x O|CSZ|M + M_x O, Pt$$ where M=C, Ni, Co or Fe; and then by examining all the possible permutations of heterogenous cells with these four oxygen buffers. Simultaneous linear regression of all the data (624 readings from 14 different cells) shows that the overall precision of the results is ±100 J/mol (one standard deviation). The results are in good agreement with the available calorimetric data. Although the agreement with previous electrochemical work is also good, the high precision of the present results reveals small systematic differences, and accordingly we recommend small adjustments to the existing values for these buffers. The revised equations are ( $$\mu _{O_2 } $$ in J/mol, temperature in K, reference pressure 105 Pa): $$\begin{gathered} Cu - Cu_2 O( \pm 80): \hfill \\ - 347,705 + 246.096 T \hfill \\ - 12.9053 T In T (700〈 T〈 1,338) \hfill \\ Ni - NiO( \pm 200): \hfill \\ - 478,967 + 248.514 T \hfill \\ - 9.7961 T In T (700〈 T〈 1.700) \hfill \\ Co - CoO( \pm 200): \hfill \\ - 492,186 + 509.322 T - 53.284 T In T \hfill \\ + 0.02518 T^2 (700〈 T〈 1,394) \hfill \\ - 484,276 + 235,092 T \hfill \\ - 11.3440 T In T(1,394〈 T〈 1,760) \hfill \\ \end{gathered} $$ We also report new data for the W-WO2 buffer. The results, which are also in very good agreement with the calorimetric data, are: $$\begin{gathered} W - WO_2 ( \pm 300): \hfill \\ = - 569,087 + 300.479 T \hfill \\ - 15.9697 T In T(700〈 T〈 1,700) \hfill \\ \end{gathered} $$ .
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01046533
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  • 5
    Electronic Resource
    Electronic Resource
    Thermodynamic data from redox reactions at high temperatures. III. Activity-composition relations in Ni-Pd alloys from EMF measurements at 850–1250 K, and calibration of the NiO+Ni-Pd assemblage as a redox sensor (1994)
    Springer
    Contributions to mineralogy and petrology 116 (1994), S. 327-339 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The assemblage NiO+Ni-Pd alloy has been calibrated as a precise oxygen fugacity sensor in the temperature range 850–1250 K at 1 bar, using an electrochemical technique with oxygen-specific CSZ electrolytes, and Ni+NiO and Cu+Cu2O as the reference electrodes. Nine compositions were studied, ranging from 0.12 to 0.83 X Ni alloy . Steady EMFs, implying equilibrium, were rapidly achieved in all cells, and were found to be reversible on increasing and decreasing temperature with a precision approaching 0.1 mV. The estimated accuracy of the measurements on each cell is ±0.2 mV (1σ, corresponding to ±0.003 log-bar units in fo2 at 1273 K). Compositions of the Ni-Pd alloys were measured after each run by electron microprobe, and these compositions were then checked for internal consistency by measuring the lattice parameter by X-ray diffraction. Nickel-rich alloys show positive deviations from ideality and endothermic enthalpies of mixing, but palladium-rich compositions have exothermic enthalpies of mixing and strong negative deviations from ideality. The excess entropies of mixing are positive for all compositions, and correlate approximately with the excess volumes of mixing. The highly asymmetrical deviations from ideality are well described by a polynomial expression of the Redlich-Kister form, with three terms for the enthalpies, and two for the excess entropies and volumes of mixing. The experimental data from this study have been used to re-formulate the Ni-Pd oxygen fugacity sensor to give an expression; μ O2 ss = μ O2 NNO − 2RT ln X Ni alloy − [2 · (1 − X Ni alloy )2 · [(−2165−7.958 · T) + (9409 − 0.888 · T) · (4 X Ni alloy − 1) + 2089 · (6 X Ni alloy − 1) · (2 X Ni alloy − 1)]](850〈T〈1300) where μ O2 ss is in J mol-1, T is in kelvins, and the expression for μ O2 NNO is that given by O'Neill and Pownceby (1993). Values in terms of log fo2 may be obtained from the above by dividing by RT ln 10. The estimated standard error in μ O2 ss is on the order of ±200 J mol-1, which is approximately ±0.01 log-bar units in fo2 at 1273 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00306501
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  • 6
    Electronic Resource
    Electronic Resource
    Thermodynamic data from redox reactions at high temperatures. VI. Thermodynamic properties of CoO–MnO solid solutions from emf measurements (2000)
    Springer
    Contributions to mineralogy and petrology 140 (2000), S. 28-39 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Activities of CoO in (Co,Mn)O solid solutions in contact with metallic Co have been determined on ten compositions ranging from 0.12 to 0.84 XCoO in order to calibrate the divariant equilibrium between (Co,Mn)O oxide solutions and Co metal as an oxygen fugacity sensor for application in experimental petrology. Experiments were conducted over the temperature range 900–1300 K at 1 bar, using an electrochemical technique with oxygen-specific calcia-stabilized zirconia (CSZ) electrolytes. Co + CoO or Fe + FeO was used as the reference electrode. Compositions of the (Co,Mn)O solid solutions were measured after each run by electron microprobe, and these were checked for internal consistency by measuring the lattice parameter by X-ray diffraction. Activity–composition relations were fitted to the Redlich–Kister formalism. (Co,Mn)O solid solutions exhibit slight positive deviations from ideality, which are symmetrical (corresponding to a regular solution mixing model) across the entire composition range with A0 G = 3690(±47) Jmol−1. Excess entropies and enthalpies were also derived from the emf data and gave Sex=0.77(±0.08) JK−1 mol−1 and Hex=4558(±90) Jmol−1 respectively. The experimental data from this study have been used to formulate the (Co,Mn)O/Co oxygen fugacity sensor to give an expression: where μO2 CoCoO=−492,186 + 509.322 T − 53.284 T lnT + 0.02518 T2, taken from O'Neill and Pownceby (1993).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004100000162
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  • 7
    Electronic Resource
    Electronic Resource
    Thermodynamic data from redox reactions at high temperatures. II. The MnO-0Mn3O4 oxygen buffer, and implications for the thermodynamic properties of MnO and Mn3O4 (1993)
    Springer
    Contributions to mineralogy and petrology 114 (1993), S. 315-320 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The $$\mu _{O_2 } $$ defined by the reaction 6 MnO+O2 =2 Mn3O4 has been determined from 917 to 1,433 K using electrochemical cells (with calcia-stabilized zirconta, CSZ) of the type: Steady emfs were achieved rapidly at all temperatures on both increasing and decreasing temperature, indicating that the MnO-Mn3O4 oxygen buffer equilibrates relatively easily. It therefore makes a useful alternative choice in experimental petrology to Fe2O3-Fe3O4 for buffering oxygen potentials at oxidized values. The results are (in J/mol, temperature in K, reference pressure 1 bar); $$\mu _{O_2 } $$ (±200)=-563,241+1,761.758T-220.490T inT+0.101819T 2 with an uncertainty of ±200 J/mol. Third law analysis of these data, including a correction for the deviations in stoichiometry of MnO, impliesS 298.15 for Mn3O4 of 166.6 J/K · mol, which is 2.5 J/K · mol higher than the calorimetric determination of Robie and Hemingway (1985). The low value of the calorimetric entropy may be due to incomplete ordering of the magnetic spins. The third law value of Δ r H 298.15 0 is-450.09 kJ/mol, which is significantly different from the calorimetric value of-457.5±3.4 kJ/mol, calculated from Δ f H 298.15 0 of MnO and Mn3O4, implying a small error in one or both of these latter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01046534
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  • 8
    Electronic Resource
    Electronic Resource
    Thermodynamic data from redox reactions at high temperatures. IV. Calibration of the Re-ReO2 oxygen buffer from EMF and NiO+Ni-Pd redox sensor measurements (1994)
    Springer
    Contributions to mineralogy and petrology 118 (1994), S. 130-137 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The chemical potential of oxygen defined by the equilibrium: $$\operatorname{Re} (solid) + O_2 (gas) = \operatorname{Re} O_2 (solid)$$ has been measured between 850 and 1250 K via an electrochemical method using calcia-stabilized zirconia electrolytes and either Ni+NiO or Cu+Cu2O as the reference electrode. The results are: $$\begin{array}{*{20}c} {\mu O_2 ^{\operatorname{Re} + \operatorname{Re} O_2 } ( \pm 400) = - 451020 + 297.595 T} \\ { - 14.6585 T In T(850〈 T〈 1250)} \\ \end{array} $$ where μO2 is in J·mol-1,T in kelvins, and the reference pressure for O2 is 1 bar (105 Pa). (Values in terms of log- $$f_{O_2 }$$ may be obtained from the above expression by dividing by RTln10, whereR=8.31441 J.K-1·mol-1). The standard enthalpy of formation of ReO2 is-444.350±0.400 (1σ) kJ·mol-1, requiring a significant modification to previously published estimates. These results were checked in hydrothermal experiments using the double capsule method with NiO+Ni−Pd alloy as an oxygen sensor. Reversals atP=1 kbar over theT range 823 to 1073 K are in good agreement with the electrochemical measurements. These latter results also serve to demonstrate: (1) the usefulness of the “redox sensor” method; (2) the viability of using Re+ReO2 as a buffer in hydrothermal experiments. Re+ReO2 lies nearly midway between the Ni+NiO and Fe3O4+Fe2O3 buffers in μO2-T space, and thus fills a petrologically important gap in the range of μO2s which can be covered by accurately calibrated oxygen buffers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01052864
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  • 9
    Electronic Resource
    Electronic Resource
    Phase equilibria in the systems Fe2O3-MgO-TiO2 and FeO-MgO-TiO2 between 1173 and 1473 K, and Fe2+-Mg mixing properties of ilmenite, ferrous-pseudobrookite and ulvöspinel solid solutions (1999)
    Springer
    Contributions to mineralogy and petrology 135 (1999), S. 198-211 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Detailed phase relations have been determined within the systems Fe2O3-MgO-TiO2 and FeO-MgO-TiO2. Experiments were performed over the temperature interval 1173–1473 K by equilibrating pelletized, fine-grained oxide mixtures in either inert calcia-stabilized zirconia pots (Fe2O3-MgO-TiO2 system) or evacuated silica tubes (FeO-MgO-TiO2 system). Equilibrium phase assemblages were determined by combined optical microscope, X-ray diffraction and EMP examination. Phase relations in the Fe2O3-MgO-TiO2 ternary are dominated by the instability of the M2O3 solid solution relative to the phase assemblage M3O4 + M3O5. A miscibility gap along the M2O3 binary also gives rise to two, 3-phase fields (α-M2O3 + M3O5 + M3O4 and α′-M2O3 + M3O5 + M3O4) separated by the M3O4 + M3O5 phase field. Phase relations in the FeO-MgO-TiO2 ternary were divided into two sub-systems. For the FeTiO3-MgTiO3-TiO2 sub-ternary, there is complete solid solution along the M2O3 and M3O5 binary joins at high temperature. At low temperatures (T 〈 1373 K) the M3O5 pseudobrookite solid solution decomposes to M2O3 + TiO2. Increasing the concentration of MgO in M3O5 phase results in a decrease in the temperature at which M3O5 becomes unstable and compositional tie lines linking M2O3 and TiO2 fan out, before the appearance of a three-phase region where M2O3, M3O5, and TiO2 coexist. Within the expanded FeO-MgO-TiO2 system, at temperatures above ∼1273 K there is a continuous solid solution along the M3O4 binary. At low temperatures (T 〈 1273 K) the Mg2TiO4 end-member breaks down to MgO and MgTiO3. The M3O4 phase shows significant non-stoichiometry, down to at least 1173 K. Fe2+-Mg partitioning data were obtained for coexisting M2O3-M3O5 and M2O3-M3O4 pairs in the FeO-MgO-TiO2 ternary. Assuming a regular solution mixing model for all phases, the M2O3 and M3O4 solid solutions were both found to exhibit moderate positive deviations from ideality (∼2600 J/mol), whereas the data for the M3O5 binary suggest close to ideal behaviour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004100050506
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  • 10
    Electronic Resource
    Electronic Resource
    Activity-composition relations in FeTiO3-MnTiO3 ilmenite solid solutions from EMF measurements at 1050–1300 K (1989)
    Springer
    Contributions to mineralogy and petrology 103 (1989), S. 216-222 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The activity of FeTiO3 in the binary ilmenitepyrophanite (FeTiO3-MnTiO3) solid solution has been determined for the temperature range 1050–1300 K by displacement of the reaction: 2 FeTiO3=2 Fe+2 TiO2+O2 in T-μO2 space, using an electrochemical technique with calcia- and yttria-stabilized zirconia solid electrolytes. The activities show small positive deviations from ideality, which, although the data are unusually precise, may be perfectly described by the simple regular solution model, with an interaction parameter, W Fe-Mn ilm , of 2.2±0.3 kJ g-atom−1, which is independent of temperature. This value, together with the experimental data on the partitioning of Fe and Mn between ilmenite and garnet (Pownceby et al. 1987), gives W Fe-Mn gt =1.2±0.5 kJ g-atom−1 for the almandine-spessartine (Fe3Al2Si3O12-Mn3Al2Si3O12) solid solution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00378507
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