Microstructural Observations of α-Quartz Amorphization

Kingma, Kathleen J.; Meade, Charles; Hemley, Russell J.; Mao, Ho‐kwang; Veblen, David R.

doi:10.1126/science.259.5095.666

Cited by 230 publications

(146 citation statements)

References 33 publications

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“…Hemley (1987) reported first the occurrence of a crystal to crystal phase transition for coesite at around 25GPa before the onset of pressure induced amorphization. Kingma et al (1993a; found a similar crystal to crystal transition in a-quartz metastably compressed to 21 GPa, preceding or accompanying pressure-induced amorphization (Figs. 8 and 9).…”

Section: New Polymorphsmentioning

confidence: 90%

New experimental developments in Raman spectroscopy at high pressures and temperatures on crystalline and amorphous phases

Gillet

1997

Phase Transitions

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Recent developments in Raman spectroscopy at high pressure, high temperature and combined high pressure and variable temperature are presented. The instrumental and technical aspects of Raman spectroscopy, and coupling 'of diamond anvil cells and miniature furnaces to Raman microspectrometers are discussed. Several pitfalls are discussed: (1) the generation of shear stresses on the sample during room temperature compression and their effects on phase transitions; (2) thermal radiation during hightemperature measurements; (3) thermal pressure in laser heated diamond anvil cells. The application of in-situ Raman spectroscopy to the study of phase transitions occurring at extreme pressures is illustrated & the new recently discovered phase transformations in the SiOz system: quartz I + quartz I1 or pressure-induced amorphization of quartz. Finally, it is shown how vibrational mode anharmonicity can be obtained from the pressure-and temperature-induced shifts of Raman modes. Accurate determination of these shifts in conjunction with well-defined equation of states permits a separation of the temperature dependence of a phonon frequency into its two components: the implicit volume-driven (quasi-harmonic) contribution produced by thermal expansion and the explicit phonon-excitation (intrinsic anharmonicity) contribution or phonon-phonon interaction. This last point is illustrated by the example of the hard Raman modes of MgzSiO4-forsterite and Si02-quartz.

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Section: New Polymorphsmentioning

confidence: 90%

New experimental developments in Raman spectroscopy at high pressures and temperatures on crystalline and amorphous phases

Gillet

1997

Phase Transitions

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“…The resulting structure exhibited a degree of anisotropy, as observed by McNeil and Grimsditch [50], whereas a quenched melt is isotropic. Kingma et al [40,41] observed that pressure-amorphized samples from 22 to 30 GPa had a phase transformation prior to amorphization, at around 21 GPa, and a return to a quartz-like structure on unloading, suggesting memory effects on quartz. Beyond 30 GPa, the crystal had fully amorphized into an anisotropic phase.…”

Section: Strain-controlled Deformationmentioning

confidence: 97%

Atomic Scale Chemo-mechanics of Silica: Nano-rod Deformation and Water Reaction

Silva

Liao

et al. 2006

J Computer-Aided Mater Des

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The notion of bond rupture as the initiation event leading to mechanical failure in a material system is well known. Less recognized but no less valid is that bond strain also fundamentally affects the chemical reactivity of the atoms involved in the bonding. This dual role of bond strain is clearly brought out in the present simulations. Stress-strain response of dry silica to the point of structural instability is studied using a classical inter-atomic potential model, whereas transition-state pathway sampling of water-silica reaction is performed using molecular orbital theory. Although not as accurate as possible from the standpoint of existing methods of simulation, the results nevertheless illustrate the physical insights into chemo-mechanical processes one can extract through multi-scale modeling and simulation.

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“…It has been later observed by transmission electron microscopy [100] that the first step of amorphization occurs by the formation of planar defects, followed by the formation of the amorphous phase on the defect sites. Indeed, these planar defects are due to the formation of one crystalline phase at 21 GPa [101].…”

Section: Examplesmentioning

confidence: 99%

Optical Spectroscopy Methods and High‐Pressure–High‐Temperature Studies

Polian

Simon

Pagès³

2010

Thermodynamic Properties of Solids

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This chapter aims to show how optical spectroscopies contribute to the study of vibrational properties under extreme conditions. Now, what do we mean by extreme conditions? We can take it in the other way and mention that ambient conditions have nothing more special as to permit life on earth -that is already not bad! From the point of view of physics, no particular property occurs at ambient conditions. On the contrary, most of the matter in the universe is under extreme pressure (P) and temperature (T), as it is in planets, stars, and more exotic objects. Studies at high pressure and high temperature are hence only the study of matter in its normal conditions. The reason why geoscientists are much interested in such studies is self-explanatory, but other fields are widely studied. The application of high pressure and high temperature enables to explore the repulsive part of the potential energy (fundamental physics), to provoke phase transformations thereby leading to new structures eventually metastable at ambient conditions (materials sciences), to orient chemical reactions in requested directions (chemistry), and even to crystallize proteins, that otherwise would not happen by using other techniques (biology). Another interest to work under variable conditions is that, obviously, more insight is given into the considered phenomenon, in that the pressure and/or temperature derivatives of the phenomenon become available, thus offering a more complete picture to achieve optimum understanding and/or modeling.There are mainly five experimental methods to probe the vibrational properties of matter: optical spectroscopies (of main interest here), ultrasonics (US), inelastic neutron scattering (INS, cf. Chapter 3), more recently inelastic X-ray scattering (IXS, cf. Chapter 4) -that was made possible due to the introduction of third generation synchrotron radiation facilities -and picosecond (PS) acoustics.INS and IXS are used to determine the dispersion of vibration modes, that is, acoustical as well as optical ones, over the whole Brillouin zone (BZ). The most stringent limitations are the needed sources (national-size ones, i.e., a nuclear reactor for INS and a monochromatized X-ray beam as delivered by a synchrotron for IXS), and a limitation to small momentum transfer (q < 0.1q BZB , where q is the magnitude of the wavevector and BZB is the BZ boundary). An additional limitation for INS is

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Microstructural Observations of α-Quartz Amorphization

Cited by 230 publications

References 33 publications

New experimental developments in Raman spectroscopy at high pressures and temperatures on crystalline and amorphous phases

New experimental developments in Raman spectroscopy at high pressures and temperatures on crystalline and amorphous phases

Atomic Scale Chemo-mechanics of Silica: Nano-rod Deformation and Water Reaction

Optical Spectroscopy Methods and High‐Pressure–High‐Temperature Studies

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