Elements, Oxides, and Silicates. High-Pressure Phases with Implications for the Earth's Interior

Sclar, C. B.

doi:10.1016/0016-7037(88)90243-8

Cited by 13 publications

(31 citation statements)

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“…The main structural differences between the high-and low-density phases reflect the way that the different polyhedral structural units are clustered, both the simulation and diffraction studies indicating a shift to higher values of radial distance for the Y-Y correlation. Such subtle changes are consistent with more recent versions of the two-state model in which the two 'crystal-like' species are replaced by the broken and unbroken bonds in a quasi-crystalline lattice [24][25][26]. In these recent models, the non-ideal interaction parameter (W ) of the original Rapoport model [13] is viewed as a measure of cooperativity (clustering) of the excited and non-excited parts of this bond lattice.…”

Section: Discussionsupporting

confidence: 77%

“…The phenomenon of melting is also usually associated with an increase in volume (positive V m ) because of increased thermal motion and the liquid accessing additional degrees of structural freedom. However, many simple systems show a negative melting slope, at least within certain pressure intervals, and there can be one or more maxima in the melting curves [13,[25][26][27]. Examples of elements exhibiting such behaviour include the metals Ba (melting curve maximum at 2 GPa; perhaps also two others between 6 and 8 GPa), Cs (a double maximum separated by the bcc-fcc phase transition at 2.5 GPa), Ti (negative initial slope to 8 GPa; likely maximum near 1 atm), Eu (maximum at 3 GPa) and Pu (negative initial slope to 3 GPa); the semiconductors Si and Ge (negative initial slopes, with potential maxima at 'negative pressures') and Se and Te (maxima at 5 and 2 GPa, respectively).…”

Section: Introductionmentioning

confidence: 99%

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Polyamorphism in aluminate liquids

McMillan

Wilson

Wilding

2003

J. Phys.: Condens. Matter

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Supercooled liquids in the Y 2 O 3 -Al 2 O 3 system undergo a liquid-liquid phase transition between a high-temperature, high-density amorphous polymorph (HDA form), and one with lower density that is stable at lower temperature (LDA form). The two amorphous polymorphs have the same chemical composition, but they differ in their density (∼4% density difference), and in their heat content (enthalpy) and entropy determined by calorimetry. Here we present new results of structural studies using neutron and high-energy x-ray diffraction to study the structural differences between high-density amorphous (HDA) and low-density amorphous (LDA) polyamorphs. The combined data sets show no large differences in the average nearest-neighbour Al-O or Y-O bond lengths or coordination numbers between the low-and high-density liquids. However, the data indicate that changes occur among the packing geometries and clustering of the Al-O and Y-O coordination polyhedra, i.e., within the second-nearest-neighbour shell defined by the metalmetal (i.e., Y-Y, Y-Al and Al-Al) interactions. Polarizable ion molecular dynamics simulations of Y 2 O 3 -Al 2 O 3 liquids are used to help interpret the pair-correlation functions obtained from x-ray and neutron scattering data. Unexpectedly large density fluctuations are observed to occur during the simulation, that are interpreted as due to dynamic sampling of high-and low-density configurations within the single-phase liquid at temperatures above the critical point or phase transition line. Calculated partial radial distribution functions indicate that the primary differences between HDA and LDA configurations occur among the Y-Y correlations.

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Section: Discussionsupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Polyamorphism in aluminate liquids

McMillan

Wilson

Wilding

2003

J. Phys.: Condens. Matter

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“…The structural properties of quart are calculated in a pressure range from 0 to 5 GPa in this work. The quartz transforms into coesite at about 2 GPa, [41] then transform into stishovite at 8 GPa, [42] and then transform into CaCl2-structure phase at 51 GPa, [43] and then transform into α-PbO2-structure phase at 98 GPa. [44] Though the pressure up to 5 GPa, no phase transitions happen in this study because the simulated temperature is 0 K.…”

Section: Lattice Parameters and Pressurementioning

confidence: 99%

First-principles simulation of Raman spectra and structural properties of quartz up to 5 GPa

Liu

et al. 2015

Chinese Phys. B

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“…Si02 is one of the most abundant coumpounds on Earth. Because the high-pressure polymorphic transitions in Si02 might place significant constraints on the evolution of the interior of the Earth and of the other terrestrial planets, its P-T (temperature-pressure) phase diagram and the physical properties of the various polymorphs have been widely invesij ��ed (see Liu and Bassett, 1986 for a detailed description). Similarly, the nature of the pb;�)� behavior of several analogous dioxides at high pressures has also been exten sivelyJrstu _ died (Liu, 1982;Ming and Manghnani, 1982).…”

Section: Introduction 111mentioning

confidence: 99%

“…!fU)fHn� �L Detail�.SbBfoi se relationships of the various dioxides are described in Liu and Bassett (1986. )1 oodo-some of the important dioxides hace been studied by Ming and Manghnani (l 982:}ioH@Wever, their results are not consistent in terms of identifying the high-pressure phaserr(�u&libas Zr02) and predicting a post-rutile phase transition (such as Si02).…”

Section: Introduction 111mentioning

confidence: 99%

Compression Studies of Single-Crystal SnO2 and PbO2 in a Diamond Cell

Huang¹,

Li²,

Yu³

1992

Terr. Atmos. Ocean. Sci.

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Compression behaviors of two single-crystal rutile-structure dioxides, Sn02 (cassiterite) and Pb02 (plattnerite), were studied in a Merrill-Bassett type diamond cell at room temperature. The samples were compressed in a mixture of 4: 1 methanol ethenol solution with pressure measurements by the ruby scale. A four-circle diffractometer was used to obtain the diffraction patterns of these crystals at high pressures. Compression results on Sn02 did not show significant lattice distortion, with a slight increase inc/a up to 35 kbar. The compression data are in excellent agreement with Hazen and Finger (1981) and in reasonable agreement with Ming and Manghnani (1982). Fitting these data to the Birch-Mumaghan equation gives a bulk modulus (K0) of 2.24 ± 0.08 Mbar with K0'= 6.3. On the other hand, the rutile-type Pb02 was found to transform from a tetragonal to an orthorhombic phase above 5 kbar. The cell parameters a, b and c of this phase have different linear compressibility. This phase is different from the reported orthorhombic phases of lead dioxides (a-Pb02). It could represent an intermediate distorted phase which occurs during the transformation from the J3-Pb02 to the a-Pb02 phase. The bulk modulus of Pb02 was determined to be 1.34 ± 0.06 Mbar by fitting the data to the Birch-Mumaghan equation. A linear relationship was found to exist between the bulk sound velocity and mean atomic weight of the rutile-type diox ides.

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Elements, Oxides, and Silicates. High-Pressure Phases with Implications for the Earth's Interior

Cited by 13 publications

References 0 publications

Polyamorphism in aluminate liquids

Polyamorphism in aluminate liquids

First-principles simulation of Raman spectra and structural properties of quartz up to 5 GPa

Compression Studies of Single-Crystal SnO2 and PbO2 in a Diamond Cell

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