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  • 1
    Monographie ausleihbar
    Monographie ausleihbar
    Cambridge [u.a.] : Cambridge Univ. Press
    Signatur: 11/M 04.0513
    Beschreibung / Inhaltsverzeichnis: describes the interaction between geophysics and condensed matter physics. Condensed matter physics leads to a first-principles way of looking at crystals, enabling physicists and mineralogists to study the rich and sometimes unexpected behavior that minerals exhibit under the extreme conditions, such as high pressure and high temperature, found deep within the earth. Leading international researchers from both geosciences and condensed matter physics discuss the state-of-the-art of this interdisciplinary field. A summary for specialists and graduate students researching mineralogy and crystallography.
    Materialart: Monographie ausleihbar
    Seiten: XVIII, 397 S. , Ill., graph. Darst.
    ISBN: 0521643422
    Klassifikation:
    Mineralogie
    Standort: Kompaktmagazin oben
    Zweigbibliothek: GFZ Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Monographie ausleihbar
    Monographie ausleihbar
    Washington, D.C. : Mineralogical Society of America
    Dazugehörige Bände
    Signatur: 11/M 99.0430 ; 11/M 00.0102 ; 11/M 99.0037
    In: Reviews in mineralogy
    Beschreibung / Inhaltsverzeichnis: This volume was prepared for a short course by the same title, organized by Russell J. Hemley and Ho-kwang Mao and sponsored by the Mineralogical Society of America, December 4-6, 1998 on the campus of the University of California at Davis. High-pressure mineralogy has historically been a vital part of the geosciences, but it is only in the last few years that the field has emerged as a distinct discipline as a result of extraordinary recent developments in high-pressure techniques. The domain of mineralogy is now no less than the whole Earth, from the deep crust to the inner core-the entire range of pressures and temperatures under which the planet's constituents were formed or now exist. The primary goal of this field is to determine the physical and chemical properties of materials that underlie and control the structural and thermal state, processes, and evolution of the planet. New techniques that have come 'online' within the last couple of years make it possible to determine such properties under extreme pressures and temperatures with an accuracy and precision that rival measurements under ambient conditions. These investigations of the behavior of minerals under extreme conditions link the scale of electrons and nuclei with global processes of the Earth and other planets in the solar system. It is in this broad sense that the term 'Ultrahigh-Pressure Mineralogy' is used for the title of this volume of Reviews in Mineralogy. This volume sets out to summarize, in a tutorial fashion, knowledge in this rapidly developing area of physical science, the tools for obtaining that knowledge, and the prospects for future research. The book, divided into three sections, begins with an overview (Chapter 1) of the remarkable advances in the ability to subject minerals-not only as pristine single-crystal samples but also complex, natural mineral assemblages-to extreme pressure-temperature conditions in the laboratory. These advances parallel the development of an arsenal of analytical methods for measuring mineral behavior under those conditions. This sets the stage for section two (Chapters 2-8) which focuses on high-pressure minerals in their geological setting as a function of depth. This top-down approach begins with what we know from direct sampling of high-pressure minerals and rocks brought to the surface to detailed geophysical observations of the vast interior. The third section (Chapters 9-19) presents the material fundamentals, starting from properties of a chemical nature, such as crystal chemistry, thermochemistry, element partitioning, and melting, and moving toward the domain of mineral physics such as melt properties, equations of state, elasticity, rheology, vibrational dynamics, bonding, electronic structure, and magnetism. The Review thus moves from the complexity of rocks to their mineral components and finally to fundamental properties arising directly from the play of electrons and nuclei. The following themes crosscut its chapters. Composition of the mantle and core Our knowledge of the composition of the Earth in part is rooted in information on cosmochemical abundances of the elements and observations from the geological record. But an additional and essential part of this enterprise is the utilization of the growing information supplied by mineral physics and chemistry in detailed comparison with geophysical (e.g. seismological) observations for the bulk of the planet. There is now detailed information from a variety of sources concerning crust-mantle interactions in subduction (Liou et aI., Chapter 2; Mysen et aI., Chapter 3). Petrological, geochemical, and isotope studies indicate a mantle having significant lateral variability (McDonough and Rudnick, Chapter 4). The extent of chemical homogeneity versus layering with depth in the mantle, a question as old as the recognition of the mantle itself, is a first-order issue that threads its way throughout the book. Agee (Chapter 5) analyzes competing models in terms of mineral physics, focusing on the origin of seismic discontinuities in the upper mantle. Bina (Chapter 6) examines the constraints for the lower mantle, with particular emphasis given to the variation of the density and bulk sound velocity with depth through to the core-mantle boundary region (Jeanloz and Williams, Chapter 7). Stixrude and Brown (Chapter 8) examine bounds on the composition of the core. Mineral elasticity and the link to seismology The advent of new techniques is raising questions of the mineralogy and composition of the deep Interior to a new level. As a result of recent advances in seismology, the depth-dependence of seismic velocities and acoustic discontinuities have been determined with high precision, lateral heterogeneities in the planet have been resolved, and directional anisotropy has been determined (Chapters 6 and 7). The first-order problem of constraining the composition and temperature as a function of depth alone is being redefined by high-resolution velocity determinations that define lateral chemical or thermal variations. As discussed by Liebermann and Li (Chapter 15), measurements of acoustic velocities can now be carried out simultaneously at pressures that are an order of magnitude higher, and at temperatures that are a factor of two higher, than those possible just a few years ago. The tools are in hand to extend such studies to related properties of silicate melts (Dingwell, Chapter 13). Remarkably, the solid inner core is elastically anisotropic (Chapter 8); with developments in computational methods, condensed-matter theory now provides robust and surprising predictions for this effect (Stixrude et aI., Chapter 19), and with very recent experimental advances, elasticity measurements of core material at core pressures can be performed directly (Chapters 1 and 15). Mantle dynamics The Earth is a dynamic planet: the rheological properties of minerals define the dynamic flow and texture of material within the Earth. Measurement of rheological properties at mantle pressures is a significant challenge that can now be addressed (Weidner, Chapter 16). Deviatoric stresses down to 0.1 GPa to pressures approaching 300 GPa can be quantified in high-pressure cells using synchrotron radiation (Chapter 1). The stress levels are an appropriate scale for understanding earthquake genesis, including the nature of earthquakes that occur at great depth in subducted slabs (deep-focus earthquakes) as these slabs travel through the Earth's mantle. Newly developed high-pressure, high-precision x-ray tools such as monochromatic radiation with modern detectors with short time resolution and employing long duration times are now possible with third-generation synchrotron sources to study the rheology of deep Earth materials under pressure (Chapter 1). Fate of subducting slabs One of the principal interactions between the Earth's interior and surface is subduction of lithosphere into the mantle, resulting in arc volcanoes, chemical heterogeneity in the mantle, as well as deep-focus earthquakes (Chapters 2 and 3). Among the key chemical processes associated with subduction is the role of water in the recycling process (Prewitt and Downs, Chapter 9), which at shallower levels is essential for understanding arc volcanism. Mass and energy transport processes govern global recycling of organic and inorganic materials, integration of these constituents in the Earth's interior, the evolution (chemically and physically) of descending slabs near convergent plate boundaries, and the fate of materials below and above the descending slab. Chapters 5 and 6 discuss the evidence for entrainment and passage of slabs through the 670 km discontinuity, and the possibility of remnant slabs in the anomalous D" region near the core-mantle boundary (Chapter 7). The ultimate fate of the materials cycled to such depths may affect interactions at the core-mantle boundary and may also hold clues to the initiation of diapiric rise. The evolution and fate of a subducting slab can now be addressed by experimental simulation of slab conditions, including in situ monitoring of a simulated slab in high-pressure apparatus in situ x-ray and spectroscopic techniques. The chemistry of volatiles changes appreciably under deep Earth conditions: they can be structurally bound under pressure (Prewitt and Downs, Chapter 9). Melting Understanding pressure-induced changes in viscosity and other physical properties of melts is crucial for chemical differentiation processes ranging from models of the magma ocean in the Earth's early history to the formation of magmatic ore deposits. (Chapter 13). Recent evidence suggests that melting may take place at great depth in the mantle. Seismic observations of a low-velocity zone and seismic anisotropy at the base of the mantle have given rise to debate about the existence of regions of partial melt deep in the mantle (Chapter 7). Deep melting is also important for mantle convection from subduction of the lithosphere to the rising of hot mantle plumes. Very recent advances in determination of melting relations of mantle and core materials with laser-heating techniques are beginning to provide accurate constraints (Shen and Heinz, Chapter 12). Sometimes lost in the debate on melting curves is the fact that a decade ago, there simply were no data for most Earth materials, only guesses and (at best) approximate models. Moreover, it is now possible to carry out in situ melting studies on multi-component systems, including natural assemblages, to deep mantle conditions. These results address whether or not partial melting is responsible for the observed seismic anomalies at the base of the mantle and provide constraints for mantle convection models (Chapter 7). The enigma of the Earth's core The composition, structure, formation, evolution, and current dynamic state of the Earth's core is an area of tremendous excitement (Chapter 8). The keys to understanding the available geophysical data are the material properties of liquid and crystalline iron under core conditions. New synchrotron-based methods and new developments in theory are being applied to determine all of the pertinent physical properties, and in conjunction with seismological and geodynamic data, to develop a full understanding of the core and its interactions with the mantle (Chapter 7). There has been considerable progress in determining the melting and phase relations of iron into the megabar range with new techniques (Chapter 12). Constraints are also obtained from theory (Chapter 19). These results feed into geophysical models for the outer and inner core flow, structural state, evolution, and the geodynamo. Moreover, there is remarkable evidence that the Earth's inner core rotates at a different rate than the rest of the Earth. This evidence in turn rests on the observation that the inner core is elastically anisotropic, a subject of current experimental and theoretical study from the standpoint of mineral physics, as described above. The thermodynamic framework Whole Earth processes must be grounded in accurate thermodynamic descriptions of phase equilibria in multi-component systems, as discussed by Navrotsky (Chapter 10). New developments in this area include increasingly accurate equations of state (Duffy and Wang, Chapter 14) required for modeling of phase equilibria as well as for direct comparison with seismic density profiles through the planet. Recent developments in in situ vibrational spectroscopy and theoretical models provide a means for independently testing available thermochemical data and a means for extending those data to high pressures and temperatures (Gillet et aI., Chapter 17). Accurate determinations of crystal structures provide a basis for understanding thermochemical trends (Chapter 9). Systematics for understanding solid-solution behavior and element partitioning are now available, at least to the uppermost regions of the lower mantle (Fei, Chapter 11). New measurements for dense hydrous phases are beginning to provide answers to fundamental questions regarding their stability of hydrous phases in the mantle (Chapters 3 and 9) and the partitioning of hydrogen and oxygen between the mantle and core (Chapter 8). Novel physical phenomena at ultrahigh pressures One of the key recent findings in high-pressure research is the remarkable effect of pressure on the chemistry of the elements, at conditions ranging from deep metamorphism of crustal minerals (Chapter 2) to "contact metamorphism" at the core-mantle boundary (Chapter 7). Pressure-induced changes in Earth materials represent forefront problems in condensed-matter physics. New crystal structures appear and the chemistry of volatiles changes (Chapter 9). Pressure-induced electronic transitions and magnetic collapse in transition metal ions strongly affect mineral properties and partitioning of major, minor, and trace elements (Chapter 11). Evidence for these transitions from experiment (Chapter 18) and theory (Chapter 19) is important for developing models for Earth formation and chemical differentiation. The conventional view of structurally and chemically complex minerals of the crust giving way to simple, close-packed structures of the deep mantle and a simple iron core is being replaced by a new chemical picture wherein dense silicates, oxides, and metals exhibit unusual electronic and magnetic properties and chemistry. In the end, this framework must dovetail with seismological observations indicating an interior of considerable regional variability, both radially and laterally depending on depth (e.g. Chapters 6 and 7). New classes of global models Information concerning the chemical and physical properties of Earth materials at high pressures and temperatures is being integrated with geophysical and geochemical data to create a more comprehensive global view of the state, processes, and history of the Earth. In particular, models of the Earth's interior are being developed that reflect the details contained in the seismic record but are bounded by laboratory information on the physics and chemistry of the constituent materials. Such "Reference Earth Models" includes the development of reference data sets and modeling codes. Tools that produce seismological profiles from hypothesized mineralogies (Chapters 4 and 5) are now possible, as are tools for testing these models against 'reference' seismological data sets (Chapter 6). These models incorporate the known properties of the Earth, such as crust and lithosphere structure, and thus have both an Earth-materials and seismological orientation. Other planets The Earth cannot be understood without considering the rest of the solar system. The terrestrial planets of our solar system share a common origin, and our understanding of the formation of the Earth is tied to our understanding of the formation of its terrestrial neighbors, particularly with respect to evaluating the roles of homogeneous and heterogeneous processes during accretion. As a result of recent developments in space exploration, as well as in the scope of future planetary missions, we have new geophysical and geochemical data for the other terrestrial planets. Models for the accretion history of the Earth can now be reevaluated in relation to this new data. Experiments on known Earth materials provide the thermodynamic data necessary to calculate the high-pressure mineralogy of model compositions for the interior of Mars and Venus. Notably, the outer planets have the same volatile components as the Earth, just different abundances. Studies of the outer planets provide both an additional perspective on our own planet as well as a vast area of opportunity for application of these newly developed experimental techniques (Chapter 1 and 17). New techniques in the geosciences The utility of synchrotron radiation techniques in mineralogy has exceeded the expectations of even the most optimistic. New spectroscopic methods developed for high-pressure mineralogy are now available for characterizing small samples from other types of experiments. For example, the same techniques developed for in situ studies at high pressures and temperatures are being used to investigate microscopic inclusions such as coesite in high-pressure metamorphic rocks (Chapter 2) and deep-mantle samples as inclusions in diamond (Chapter 3). With the availability of a new generation of synchrotron radiation sources (Chapter 1) and spectroscopic techniques (Chapter 17), a systematic application of new methods, including micro tomographic x-ray analysis of whole rock samples, is now becoming routinely possible. Contributions in technology. Finally, there are implications beyond the geosciences. Mineralogy has historically has led many to conceptual and technical developments used in other fields, including metallurgy and materials science, and the new area of ultrahigh pressure mineralogy continues this tradition. As pointed out in Chapter 1, many highpressure techniques have their origins in geoscience laboratories, and in many respects, geoscience leads development of high-pressure techniques in physics, chemistry, and materials science. New developments include the application of synthetic diamond for new classes of 'large-volume' high-pressure cells. Interestingly, information on diamond stability, including its metastable growth, feeds back directly on efforts to grow large diamonds for the next generation of such high-pressure devices (Chapter 1). Microanalytical techniques, such as micro-spectroscopy and x-ray diffraction, developed for high-pressure research are now used outside of this field of research as well. The study of minerals and mineral analogs under pressure is leading to new materials. As in the synthesis of diamond itself, these same scientific approaches promise the development of novel, technological materials.
    Materialart: Monographie ausleihbar
    Seiten: xvi, 671 S.
    ISBN: 0-939950-48-0 , 978-0-939950-48-5
    ISSN: 1529-6466
    Serie: Reviews in Mineralogy 37
    Klassifikation:
    Mineralogie
    Sprache: Englisch
    Anmerkung: I. Overview Chapter 1. New Windows on the Earth's Deep Interior by Ho-kwang Mao and Russell J. Hemley, p. 1 - 32 II. Minerals in Context: The Earth's Deep Interior Chapter 2. High-pressure minerals from deeply subducted metamorphic rocks by J.G. Liou, R.Y. Zhang, W.G. Ernst, Douglas Rumble III, and Shigenori Maruyama, p. 33 - 96 Chapter 3. The Upper Mantle Near Convergent Plate Boundaries by Bjorn O. Mysen, Peter Ulmer, Juergen Konzett, and Max W. Schmidt, p. 97 - 138 Chapter 4. Mineralogy and Composition of the Upper Mantle by William F. McDonough and Roberta L. Rudnick, p. 139 - 164 Chapter 5. Phase Transformations and Siesmic Structure in the Upper Mantle and Transition Zone by Carl B. Agee, p. 165 - 204 Chapter 6. Lower Mantle Mineralogy and the Geophysical Perspective by Craig R. Bina, p. 205 - 240 Chapter 7. The Core-Mantle Boundary Region by Raymond Jeanloz and Quentin Williams, p. 241 - 260 Chapter 8. The Earth's Core by Lars Stixrude and J. Michael Brown, p. 261 - 282 Chapter 9. High-Pressure Crystal Chemistry by Charles T. Prewitt and Robert T. Downs, p. 283 - 318 III. Mineral Fundamentals: Physics and Chemistry Chapter 10. Thermodynamics of High-Pressure Phases by Alexandra Navrotsky, p. 319 - 342 Chapter 11. Solid Solutions and Element Partitioning at High Pressures and Temperatures by Yingwei Fei, p. 343 - 368 Chapter 12. High-Pressure Melting of Deep Mantle and Core Materials by Guoyin Shen and Dion L. Heinz, p. 369 - 396 in the 2002-02-07 print version, the first page of Chapter 12 (page 369) was switched with the first page of Chapter 13 (p. 397) Chapter 13. Melt Viscosity and Diffusion under Elevated Pressures by Donalds B. Dingwell, p. 397 - 424 in the 2002-02-07 print version, the first page of Chapter 12 (page 369) was switched with the first page of Chapter 13 (p. 397) Chapter 14. Pressure-Volume-Temperature Equations of State by Thomas S. Duffy and Yanbin Wang, p. 425 - 458 Chapter 15. Elasticity at High Pressures and Temperatures by Robert C. Liebermann and Baosheng Li, p. 459 - 492 Chapter 16. Rheological Studies at High Pressure by Donald J. Weidner, p. 493 - 524 Chapter 17. Vibrational Properties at High Pressures and Temperatures by Philippe Gillet, Russell J. Hemley, and Paul F. McMillan, p. 525 - 590 Chapter 18. High-Pressure Electronic and Magnetic Properties by Russell J. Hemley, Ho-kwang Mao, and Ronald E. Cohen, p. 591 - 538 Chapter 19. Theory of Minerals at High Pressure by Lars Stixrude, Ronald E. Cohen, and Russell J. Hemley, p. 639 - 671
    Standort: Lesesaal
    Standort: Lesesaal
    Standort: Lesesaal
    Zweigbibliothek: GFZ Bibliothek
    Zweigbibliothek: GFZ Bibliothek
    Zweigbibliothek: GFZ Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 10876-10882 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: The Raman-active vibron modes of solid nitrogen have been investigated by coherent anti-Stokes Raman scattering (CARS) spectroscopy to 22 GPa at room temperature. Frequencies and linewidths were measured with an accuracy of 0.1 to 0.2 cm−1. From the pressure dependence of the linewidths a dynamical model for the transitions between the δ, δloc, and ε phases has been developed. These phase transitions are characterized by different degrees of ordering of the N2 molecules. The processes can be described by an increase in the orientational order with increasing pressure and a decrease in number in the rotational degrees of freedom at the phase transitions coupled with changes in crystal structure. A structural model for the δloc phase is given, in which the δ–δloc–ε transition sequence arises from a group/subgroup relationship and can therefore be considered ferroelastic in nature. Sample annealing was found to have a significant effect on the results. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 72 (2001), S. 1302-1305 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Diffraction studies at extreme pressure-temperature conditions encounter intrinsic difficulties due to the small access angle of the diamond anvil cell and the high background of the diffraction peaks. Energy-dispersive x-ray diffraction is ideal for overcoming these difficulties and allows the collection and display of diffracted signals on the order of seconds, but is limited to one-dimensional information. Materials at high pressures in diamond anvil cells, particularly during simultaneous laser heating to temperatures greater than 3000 K often form coarse crystals and develop preferred orientation, and thus require information in a second dimension for complete analysis. We have developed and applied a diamond cell rotation method for in situ energy-dispersive x-ray diffraction at high pressures and temperatures in solving this problem. With this method, we can record the x-ray diffraction as a function of χ angle over 360°, and we can acquire sufficient information for the determination of high P–T phase diagrams, structural properties, and equations of state. Technical details are presented along with experimental results for iron and boron. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 5369-5373 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: Equation of state properties of ice VII and fluid H2O at high pressures and temperatures have been studied experimentally from 6 to 20 GPa and 300–700 K. The techniques involve direct measurements of the unit-cell volume of the solid using synchrotron x-ray diffraction with an externally heated diamond–anvil cell. The pressure dependencies of the volume and bulk modulus of ice VII at room temperature are in good agreement with previous synchrotron x-ray studies. The thermal expansivity was determined as a function of pressure and the results fit to a newly proposed phenomenological relation and to a Mie–Grüneisen equation of state formalism. The onset of melting of ice VII was determined directly by x-ray diffraction at a series of pressures and found to be in accord with previous volumetric determinations. Thermodynamic calculations based on the new data are performed to evaluate the range of validity of previously proposed equations of state for fluid water derived from static and shock-wave compression experiments and from simulations.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 656-658 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Finite-element modeling calculations reveal the origin of the remarkably large elastic strains in diamond observed in recent experiments at multimegabar pressures. This approach provides a means to determine the pressure dependence of the yield strength of strong materials used in the gasket, and allows us to examine quantities that are not accessible experimentally such as the stress and strain relations in diamond. Stress tensor elements are obtained near the tip where large modifications in the optical properties of diamond have been observed. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Earth and Planetary Sciences 29 (2001), S. 365-418 
    ISSN: 0084-6597
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The mechanisms of exchange of hydrogen between the deep interior and surface of Earth, as well as the means of retention and possible abundance of hydrogen deep within the Earth, are examined. The uppermost several hundred kilometers of Earth's suboceanic upper mantle appear to be largely degassed, but significant primordial hydrogen could be retained within the transition zone, lower mantle, or core. Regassing of the planet occurs via subduction: Cold slabs are likely particularly efficient at transporting hydrogen to depth within the planet. Marked changes in hydrogen cycling have taken place throughout Earth's history: Evidence of hydrated ultramafic melts in the Archean and probable hydrogen retention within a Hadean magma ocean indicate that early in its history, the deep Earth was substantially wetter. The largest enigma associated with hydrogen in the deep Earth lies in the core: This region could represent the dominant reservoir of hydrogen on the planet, with up to ~100 hydrospheres of hydrogen present as a high-pressure iron-alloy.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physical Chemistry 51 (2000), S. 763-800 
    ISSN: 0066-426X
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Chemie und Pharmazie , Physik
    Notizen: Abstract Recent high-pressure studies reveal a wealth of new information about the behavior of molecular materials subjected to pressures well into the multimegabar range (several hundred gigapascal), corresponding to compressions in excess of an order of magnitude. Under such conditions, bonding patterns established for molecular systems near ambient conditions change dramatically, causing profound effects on numerous physical and chemical properties and leading to the formation of new classes of materials. Representative systems are examined to illustrate key phenomena, including the evolution of structure and bonding with compression; pressure-induced phase transitions and chemical reactions; pressure-tuning of vibrational dynamics, quantum effects, and excited electronic states; and novel states of electronic and magnetic order. Examples are taken from simple elemental molecules (e.g. homonuclear diatomics), simple heteronuclear species, hydrogen-bonded systems (including H2O), simple molecular mixtures, and selected larger, more complex molecules. There are many implications that span the sciences.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Physics and chemistry of minerals 21 (1994), S. 481-488 
    ISSN: 1432-2021
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: Abstract The pressure dependence of the cristobalite Raman spectrum has been investigated to 22 GPa at room temperature, using single-crystal Raman spectroscopy with a diamond-anvil cell. We observe a rapid, first-order phase transition on increasing pressure, consistent with the cristobalite I↔II transition revealed in previous x-ray diffraction experiments. The phase transition has been bracketed at 1.2±0.1 GPa on increasing pressure and 0.2±0.1 GPa on decreasing pressure. The pressure shifts II) of 11 Raman bands in the high-pressure phase (cristobalite have been measured. Evidence for an unusual hybridization of modes at 490–500 cm−1 is found. Changes in the Raman spectra also reveal an additional phase transition to a new phase at P ≈ 11 GPa, which remains to be fully characterized.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Physics and chemistry of minerals 22 (1995), S. 277-281 
    ISSN: 1432-2021
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: Abstract Single-crystal brucite, Mg(OH)2, was studied to 14 GPa in a quasi-hydrostatic pressure medium using a diamond anvil cell and energy-dispersive synchrotron x-ray diffraction. The parameters of a third-order Birch-Murnaghan equation of state fit to the data are: K OT=42(2) GPa, and (∂K OT/∂P)T= 5.7(5). The bulk modulus is significantly lower than that obtained in recent shock compression and powder x-ray diffraction experiments under non-hydrostatic conditions. No evidence was found for a transition involving the Mg -O sub-structure over the pressure range of these experiments. This implies that the structural change previously identified at high pressure by Raman spectroscopy probably involves rearrangement of hydrogen atoms, leaving the Mg — O substructure largely unaffected.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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