4,186 research outputs found
Data for: Energetics of melting of Yb2O3 and Lu2O3 from Drop and Catch Calorimetry and First Principles Computations
No full textSupplementary information for manuscript "Energetics of melting of Yb2O3 and Lu2O3 from Drop and Catch Calorimetry and First Principles Computations" by Matthew Fyhrie, Qi-Jun Hong, Denys Kapush, Sergey V. Ushakov, Helena Liu, Axel van de Walle, Alexandra Navrotsk
Jarosite stability on Mars
No full textJarosite, a potassium (sodium) iron sulphate hydrated mineral, has recently been identified on the martian surface by the Opportunity rover. Using recent thermochemical data [Drouet and Navrotsky, 2003, Geochim. Cosmochim. Acta 67, 2063–2076; Forray et al., 2005, Geochim. Cosmochim. Acta, in press], we calculate the equilibrium decomposition curve of jarosite and show that it is thermodynamically stable under most present martian pressures and temperatures. Its stability makes jarosite potentially useful to retain textural, chemical, and isotopic evidence of past history, including possible biological activity, on Mars
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"Energetics of Nanomaterials"
No full textThis project represents a three-year collaboration among Alexandra Navrotsky, Brian Woodfield, Juliana Bocrio-Goates and Frances Hellman. It's purpose has been to explore the differences between bulk materials, nanoparticles, and thin films in terms of their thermodynamic properties, with an emphasis on heat capacities and entropies, as well as enthalpies. The three groups have brought very different expertise and capabilities to the project. Navrotsky is a solid-state chemist and geochemist, with a unique Thermochemistry Facility emphasizing enthalpy of formation measurements by high temperature oxide melt and room temperature acid solution calorimetry. Bocrio-Goates and Woodfield are physical chemists with unique capabilities in accurate cryogenic heat capacity measurements using adiabatic calorimetry. Hellman is a physicist with expertise in magnetism and heat capacity measurements using microscale ''detector on a chip'' calorimetric technology that she pioneered. The overarching question of the work is ''How does the free energy play out in nanoparticles''? or ''How do differences in free energy affect overall nanoparticle behavior''? Because the free energy represents the temperature-dependent balance between the enthalpy of a system and its entropy, there are two separate, but related, components to the experimental investigations: Solution calorimetric measurements provide the energetics and two types of heat capacity measurements the entropy. They use materials that are well characterized in other ways (structurally, magnetically, and chemically), and samples are shared across the collaboration
Geochemistry of Geologic CO2 Sequestration/ Donald J. DePaolo, David R. Cole, Alexandra Navrotsky, Ian C. Bourg.
No full textIn English.Volume 77 of Reviews in Mineralogy and Geochemistry focuses on important aspects of the geochemistry of geological CO2 sequestration. It is in large part an outgrowth of research conducted by members of the U.S. Department of Energy funded Energy Frontier Research Center (EFRC) known as the Center for Nanoscale Control of Geologic CO2 (NCGC). Eight out of the 15 chapters have been led by team members from the NCGC representing six of the eight partner institutions making up this center - Lawrence Berkeley National Laboratory (lead institution, D. DePaolo - PI), Oak Ridge National Laboratory, The Ohio State University, the University of California Davis, Pacific Northwest National Laboratory, and Washington University, St. Louis.DePaolo, Donald J. / Cole, David R. -- Bickle, Mike / Kampman, Niko / Wigley, Max -- Radha, A. V. / Navrotsky, A. -- Bodnar, Robert J. / Steele-Maclnnis, Matthew / Capobianco, Ryan M. / Rimstidt, J. Donald / Dilmore, Robert / Goodman, Angela / Guthrie, George -- Kaszuba, John / Yardley, Bruce / Andreani, Muriel -- De Yoreo, James J. / Waychunas, Glenn A. / Jun, Young-Shin / Fernandez-Martinez, Alejandro -- Power, Ian M. / Harrison, Anna L. / Dipple, Gregory M. / Wilson, Siobhan A. / Kelemen, Peter B. / Hitch, Michael / Southam, Gordon -- Chialvo, Ariel A. / Vlcek, Lukas / Cole, David R. -- Kharaka, Yousif K. / Cole, David R. / Thordsen, James J. / Gans, Kathleen D. / Thomas, R. Burt -- Crawshaw, John P. / Boek, Edo S. -- Fitts, Jeffrey P. / Peters, Catherine A. -- Tokunaga, Tetsu K. / Wan, Jiamin -- Carey, J. William Frontmatter -- Reviews -- Preface -- TABLE OF CONTENTS -- 1. Geochemistry of Geologic Carbon Sequestration: An Overview / 2. Natural Analogues / 3. Thermodynamics of Carbonates / 4. PVTX Properties of H2 0-C02-"salt" at PTX Conditions Applicable to Carbon Sequestration in Saline Formations / 5. Experimental Perspectives of Mineral Dissolution and Precipitation due to Carbon Dioxide-Water-Rock Interactions / 6. Molecular Simulation of C02- and C03-Brine-Mineral Systems -- 7. In situ Investigations of Carbonate Nucleation on Mineral and Organic Surfaces / 8. Pore Scale Processes Associated with Subsurface C02 Injection and Sequestration -- 9. Carbon Mineralization: From Natural Analogues to Engineered Systems / 10. Acid Gases in C02-rich Subsurface Geologic Environments / 11. Geochemical Monitoring for Potential Environmental Impacts of Geologic Sequestration of C02 / 12. Multi-scale Imaging and Simulation of Structure, Flow and Reactive Transport for C02 Storage and EOR in Carbonate Reservoirs / 13. Caprock Fracture Dissolution and C02 Leakage / 14. Capillary Pressure and Mineral Wettability Influences on Reservoir C02 Capacity / 15. Geochemistry of Wellbore Integrity in C02 Sequestration: Portland Cement-Steel-Brine-C02 Interactions /1 online resource (553 p.)
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DE-FG03-01ER15237 Annual Progress Report 2003
No full textOAK B262 Annual report. We have investigated the thermodynamics of several nanoscale systems: Iron oxides: We have completed and published heat capacity and entropy data on goethite, lepidocrocite, and maghemite, as well as measured their heats of formation. We also have enthalpy of formation data for several poorly crystalline nanophase oxides (schwertmannite, ferrihydrite, and epsilon-Fe{sub 2}O{sub 3}). The next step is to measure thermodynamic properties as a function of surface area for several oxides. CoO-MgO: Thermochemical data for bulk samples are in press. Heat capacities have been measured for CoO, MgO, and some intermediate samples. Nanosized samples at several compositions are being prepared this summer. Thin films have been prepared and some solution calorimetry done, but additional sample preparation and characterization is needed. Hydration energetics: Our setups for gas adsorption calorimetry and water immersion calorimetry are being completed. We will test them with known materials (Al{sub 2}O{sub 3}, selected zeolites) and then proceed to work on TiO{sub 2}, Fe{sub 2}O{sub 3}, and zeolites
Thermochemistry of yavapaiite KFe(SO4)2: Formation and decomposition
No full textYavapaiite, KFe(SO4)2, is a rare mineral in nature, but its structure is considered as a reference for many synthetic compounds in the alum supergroup. Several authors mention the formation of yavapaiite by heating potassium jarosite above ca. 400°C. To understand the thermal decomposition of jarosite, thermodynamic data for phases in the K-Fe-S-O-(H) system, including yavapaiite, are needed. A synthetic sample of yavapaiite was characterized in this work by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and thermal analysis. Based on X-ray diffraction pattern refinement, the unit cell dimensions for this sample were found to be a = 8.152 ± 0.001 Å, b = 5.151 ± 0.001 Å, c = 7.875 ± 0.001 Å, and β = 94.80°. Thermal decomposition indicates that the final breakdown of the yavapaiite structure takes place at 700°C (first major endothermic peak), but the decomposition starts earlier, around 500°C. The enthalpy of formation from the elements of yavapaiite, KFe(SO4)2, ΔH°f = −2042.8 ± 6.2 kJ/mol, was determined by high-temperature oxide melt solution calorimetry. Using literature data for hematite, corundum, and Fe/Al sulfates, the standard entropy and Gibbs free energy of formation of yavapaiite at 25°C (298 K) were calculated as S°(yavapaiite) = 224.7 ± 2.0 J.mol−1.K−1 and ΔG°f = −1818.8 ± 6.4 kJ/mol. The equilibrium decomposition curve for the reaction jarosite = yavapaiite + Fe2O3 + H2O has been calculated, at pH2O = 1 atm, the phase boundary lies at 219 ± 2°C
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Energetics of Nanomaterials
No full textThis project, "Energetics of Nanomaterials," represents a three-year collaboration among Alexandra Navrotsky (UC Davis), Brian Woodfield and Juliana Boerio-Goates (BYU), and Frances Hellman (UC Berkeley). It's purpose has been to explore the differences between bulk materials, nanoparticles, and thin films in term of their thermodynamic properties, with an emphasis on heat capaacities and entropies, as well as enthalpies. the three groups have brought very different expertise and capabilities to the project. Navrotsky is a solid-state chemist and geochemist, with a unique Thermochemistry Facility emphasizing enthalpy of formation measurements by high temperature oxide melt and room temperatue acid solution calorimetry. Boerio-Goates and Woodfield are calorimetry. Hellman is a physicist with expertise in magnetism and heat capacity measurements using microscale "detector on a chip" calorimetric technology that she pioneered. The overarching question of our work is "How does the free energy play out in nanoparticles?", or "How do differences in free energy affect overall nanoparticle behavior?" Because the free energy represents the temperature-dependent balance between the enthalpy of a system and its entropy, there are two separate, but related, components to the experimental investigations: Solution calorimetric measurements provide the energetics and two types of heat capacity measurements the entropy. We use materials that are well characterized in other ways (structurally, magnetically, and chemically), and samples are shared across the collaboration
Phase transformations in oxides above 2000°C: Experimental technique development
No full textOxidation of carbides-based ultra-high temperature ceramics is the main limiting factor for its use for aerodynamic surfaces. Experimental thermodynamic and structural data for refractory oxides above 2000 °C are mostly absent. The following techniques applied to fill this gap will be discussed: i) Commercial ultra-high temperature differential thermal analyzers (DTA) allow investigation of phase transformations and melting in inert environment to the temperatures up to 2500 °C; ii) Combination of laser heating with splittable nozzle aerodynamic levitator allow splat quenching and drop calorimetry from temperatures limited only by sample evaporation; iii) Synchrotron X-ray and neutron diffraction on laser heated aerodynamically levitated oxide samples allow in situ observation of phase transformations in variable atmosphere, refinement of high temperature structures and thermal expansion. The recent experimental findings include anomalous thermal expansion of defect fluorite structure of YSZ before melting [1] and measurement of fusion enthalpy of Y2O3, which can be used for sensitivity calibration for DTA at 2430 °C [2]. These methods provide temperatures, enthalpies and volume change on phase transformations above 2000 °C which are complementary experimental data for optimization of CalPhaD databases.
[1] Structure and Thermal Expansion of YSZ and La2Zr2O7 Above 1500 °C from Neutron Diffraction on Levitated Samples, S.V. Ushakov, A. Navrotsky, R.J.K. Weber, J.C. Neuefeind, Journal of the American Ceramic.Society 98(10), 3381 (2015)
[2] A combined experimental and theoretical study of enthalpy of phase transition and fusion of yttria above 2000 °C using “drop-n-catch” calorimetry and first-principles calculation, D. Kapush, S.V. Ushakov, A. Navrotsky, Q.-J. Hong, H. Liu, A. van de Walle, Acta Materialia 124, 204 (2017)
The work was supported by the National Science Foundation Award DMR-1506229
Author, Philosopher Alexandra Stoddard to Speak March 2 at Williams Library
No full textOXFORD, Miss. – Contemporary philosopher, author, interior designer and speaker Alexandra Stoddard gives an inspirational lecture and reading March 2 at the University of Mississippi
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