Sean Shieh

Sean Shieh
The University of Western Ontario | UWO · Department of Earth Sciences

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127
Publications
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Publications

Publications (127)
Article
The Raman spectra of Ca2Fe2O5 were investigated up to 21.8 GPa at room temperature and up to 1073 K at ambient pressure, respectively. A phase transition begins around 13.6 GPa and it is reversible after decompression. No temperature-induced phase transition was observed due to the quality of Raman spectra at temperatures above 773 K. The effects o...
Preprint
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During planetary exploration mission operations, one of the key responsibilities of the instrument teams to determine data viability for subsequent analysis. During the 2019 CanMoon Lunar Sample Return Analogue Mission, the Lead Raman Specialist manually examined each spectra to provide quality assurance/validation. This non-trivial process require...
Article
The lunar Mg-suite magmatic rocks are commonly thought to represent mafic intrusions into the anorthositic flotation crust of the lunar magma ocean (LMO). Their geochronology is, therefore, important for constraining evolution models of the LMO. Petrogenetic models of the Mg-suite hold that their parent magmas were derived from primary LMO sources...
Article
The pressure-induced phase transitions in CoCrFeNi and CoCrFeMnNi high entropy alloys (HEAs) at ambient temperature at pressure up to 24.0(2) and 19.4(2) GPa, respectively, were investigated using angle-dispersive X-ray diffraction (ADXRD). Structurally at ambient pressure, both CoCrFeNi and CoCrFeMnNi HEAs consist of face-centered cubic (fcc) stru...
Article
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Earth’s moon is a primary exploration target for space agencies around the world. The Moon records and preserves key information about fundamental processes that shape planetary crusts such as impact cratering. Understanding shock effects in lunar anorthite (Ca-rich end-member of plagioclase feldspar), the principal component of anorthosite and mos...
Article
In situ U-Pb radiometric dating of zircons is regarded as one of the most widely used and reliable methods to acquire geochronologic ages. However, it has been recently reported that radiogenic Pb (Pb*) mobilization within zircon may, in some cases, cause inaccurate age determinations with no geological significance. Such Pb* mobilization can be ca...
Article
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Plagioclase feldspar is one of the most abundant minerals on the surface of the Earth, the Moon, and Mars, and is also commonly found in meteorites. Studying shock effects in feldspar thus provides us with fundamental information about impact cratering processes on planetary bodies. In this study, plagioclase from monomict and polymict breccias, im...
Article
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Synthetic Mg2TiO4 qandilite was investigated to 50 and 40.4 GPa at room temperature using Raman spectroscopy and X-ray diffraction, respectively. The Raman measurements showed that cubic Mg2TiO4 spinel transforms to a high pressure tetragonal (I41/amd, No.141) phase at 14.7 GPa. Owing to sluggish kinetics at room temperature, the spinel phase coexi...
Article
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The Apollo 17 poikilitic impact melt breccias were initially interpreted to be directly related to the Serenitatis basin formation. Here we present petrological, geochemical, and U‐Pb geochronological investigations of the poikilitic impact melt of Apollo 73155,69 which was sampled from the South Massif of the Taurus‐Littrow valley. Nanoscale secon...
Article
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An equiatomic CoCrFeMnNi high-entropy alloy under hydrostatic compression is investigated using in-situ angular-dispersive X-ray diffraction to explore the polymorphism in high entropy alloy systems. The metallic system is of face-centered-cubic structure at ambient condition and applied hydrostatic pressures up to 20 GPa via diamond anvil cell. Th...
Article
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Co2TiO4 spinel (Co2TiO4-Sp) was synthesized at 1573 K and room P by heating in an argon atmosphere for 72 h, and quasi-hydrostatically compressed to ~ 24 GPa using a diamond-anvil cell in conjunction with a synchrotron X-ray radiation (ambient T). We found that the Co2TiO4-Sp was stable up to ~ 21 GPa and transformed to a new phase at higher P. Wit...
Article
The behavior of Ca2AlFeO5 brownmillerite was studied by in situ synchrotron X-ray diffraction and Raman spectroscopy at 300 K with pressures up to 26.5 and 32.1 GPa, respectively. A reversible structural phase transition was observed. The P–V data were fitted by a third-order Birch–Murnaghan equation of state, and the isothermal bulk modulus was ob...
Article
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A natural chromian spinel with the composition (Mg0.48(3)Fe0.52(3))(Fe0.06(1)Al0.28(1)Cr0.66(2))2O4 was investigated up to 15 GPa via synchrotron X-ray diffraction with a diamond-anvil cell at room temperature. No phase transition was clearly observed up to the maximum experimental pressure. The pressure–volume data fitted to the third-order Birch–...
Article
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The acidic sulfate-rich waters of the Meridiani Planum region were potentially a habitable environment for iron-oxidizing bacteria on ancient Mars. If life existed in this ancient martian environment, jarosite minerals precipitating in these waters may record evidence of this biological activity. Since the Meridiani jarosite is thermodynamically st...
Article
Twins in zircon are increasingly being used as an indicator of shock metamorphism on Earth and other planetary bodies, yet the conditions of their formation have not been quantified. We modeled the shear stress involved with homogeneous nucleation of the most common zircon twin(112) (Formula presented.). This stress is between 1.7 to 2.6 GPa for th...
Article
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In this study, nitrogen-doped carbon nanotubes (CNx-NTs) with a 8.4% nitrogen content were investigated under high pressure using Raman spectroscopy as well as X ray diffraction (XRD) with synchrotron radiation. For comparison purpose, high pressure behaviors of carbon nanotubes (CNTs) without nitrogen were studied as well. Two phase transformation...
Article
We present Raman patterns of enstatite in different classes of enstatite‐rich chondrites and achondrites of various shock levels as previously reported from petrographic observations and X‐ray diffraction analyses. Thin sections or mineral separates of four enstatite chondrites (LaPaz Icefield [LAP] 02225, MacAlpine Hills [MAC] 02837, Pecora Escarp...
Article
The strength and texture of sodium chloride in the B1 (rocksalt) and B2 (cesium chloride) phases were investigated in a diamond anvil cell using synchrotron X-ray diffraction in a radial geometry to 56 GPa. The measured differential stresses within the Reuss limit are in the range of 0.2 GPa for the B1 phase at pressure of 24 GPa and 1.6 GPa for th...
Article
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The pressure-dependent Raman spectra of synthetic alforsite, Ba5(PO4)3Cl, were investigated up to 34.9 GPa using a DAC at room temperature. During compression to greater than 20 GPa, new Raman active peaks of Ba5(PO4)3Cl were observed. The Raman frequencies of all observed bands for Ba5(PO4)3Cl alforsite increase continuously with increasing pressu...
Chapter
Strength and deformation microstructure of zircon were investigated to 32 GPa at room temperature using a diamond anvil cell (DAC). The obtained X-ray diffraction data were analyzed using the lattice strain theory. The high-pressure quenched samples were analyzed by electron backscatter diffraction (EBSD). Our results show a bulk modulus of 203 ± 1...
Article
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An equal-molar CoCrFeMnNi, face-centered-cubic high-entropy alloy system is investigated using in-situ angular-dispersive X-ray diffraction under hydrostatic compression up to 20 GPa via diamond anvil cell. The evolutions of multiple diffraction peaks are collected simultaneously to elucidate the phase stability field. The results indicated that an...
Article
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The vibrational properties of synthetic galaxite, MnAl2O4, were investigated at various pressures (0–29.7 GPa) and temperatures (80–973 K), respectively. The Raman frequencies of all observed bands for galaxite continuously increase with increasing pressure and decrease with increasing temperature, respectively. The quantitative analysis shows that...
Article
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Zn2TiO4 spinel (Zn2TiO4-Sp) was synthesized by a solid-state reaction method (1573 K, room P and 72 h) and quasi-hydrostatically compressed to ~24 GPa using a DAC coupled with a synchrotron X-ray radiation (ambient T). We found that the Zn2TiO4-Sp was stable up to ~21 GPa and transformed to another phase at higher P. With some theoretical simulatio...
Article
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The isothermal bulk moduli of anhydrous Mg2SiO4-ringwoodite (Rw) and Fe2SiO4-Rw, and other 4-2 oxide spinels at ambient P-T condition have been evaluated, and empirically fitted to a model as KT0 = 270.8(300) + 0.343(59)*V0 + 23.04(269)*EN-total, where KT0 is the isothermal bulk modulus in GPa, V0 the unit-cell volume in Å3 and EN-total the electro...
Article
The compressibility of the spinel solid solutions, (Mg1−xMnx)Cr2O4 with x = 0.00 (0), 0.20 (0), 0.44 (2), 0.61 (2), 0.77 (2) and 1.00 (0), has been investigated by using a diamond-anvil cell coupled with synchrotron X-ray radiation up to ∼10 GPa (ambient T). The second-order Birch–Murnaghan equation of state was used to fit the P[single bond]V data...
Conference Paper
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Introduction: Meteorite impact craters are the dominant surface feature on most terrestrial planets and provide fundamental information about planetary evolution [1]. Many terrestrial impact stuctures have been eroded to such a degree that only the underlying autochthonous target rocks are preserved or the crater structure has been infilled by late...
Article
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Using a diamond-anvil cell and synchrotron X-ray diffraction, the compressional behavior of a synthetic qandilite Mg2.00(1)Ti1.00(1)O4 has been investigated up to about 14.9 GPa at 300 K. The pressure–volume data fitted to the third-order Birch–Murnaghan equation of state yield an isothermal bulk modulus (K T0) of 175(5) GPa, with its first derivat...
Article
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In situ high-pressure synchrotron X-ray diffraction and Raman spectroscopic studies of orthorhombic CaFe2O4-type β-CaCr2O4 chromite were carried out up to 16.2 and 32.0 GPa at room temperature using multi-anvil apparatus and diamond anvil cell, respectively. No phase transition was observed in this study. Fitting a third-order Birch–Murnaghan equat...
Article
Pure larnite (β-Ca2SiO4; Lrn) was synthesized at 6 GPa and 1473 K for 6 h by using a cubic press, its thermal expansivity was investigated up to 923 K by using an X-ray powder diffraction technique (ambient P), and its compressibility was investigated up to ~16 GPa by using a diamond-anvil cell coupled with synchrotron X-ray radiation (ambient T)....
Article
The electronic structure of thallium rhenium oxide (TlReO4) at room temperature is explored as a function of applied pressure using a diamond-anvil cell and high-resolution x-ray absorption spectroscopy. We show possible evidence of charge transfer from the thallium to the rhenium atom in the high-pressure phase of this compound, thus suggesting a...
Article
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The Raman spectra of synthetic stronadelphite, Sr5(PO4)3F, were investigated up to 21.1 GPa using a diamond anvil cell at room temperature. The new splittings of the PO4 asymmetric stretching ν3b(Ag) and bending ν4b(Ag) vibrations were observed during compression. The Raman frequencies of all observed bands for stronadelphite continuously increase...
Article
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Angle-and energy-dispersive X-ray diffraction experiments in a radial geometry were performed in the diamond anvil cell on polycrystalline platinum samples at pressures up to 63 GPa. Observed yield strength and texture depend on grain size. For samples with 70-300-nm particle size, the yield strength is 5-6 GPa at ~60 GPa. Coarse-grained (~2-µm par...
Conference Paper
Spinel (AB2O4) commonly showed as a solid-solution where A is Mg, Fe or Mn and B is Cr and Al. The high-pressure chromium spinel discovered from the shocked veins of the Suizhou meteorite showed two high-pressure polymorphs with CaFe2O4 and CaTi2O4 structures that may be stable at above 12.5 and 20 GPa, respectively (Chen et al., 2003). These high-...
Article
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Sound velocities and elastic moduli of solid single-crystal CO2 were measured at pressures up to 11.7(3) GPa by Brillouin spectroscopy. The aggregate adiabatic bulk modulus (KS), shear modulus (G), and their pressure derivatives for CO2 Phase I are KS0 = 3.4(6) GPa, G0 = 1.8(2) GPa, (dKS/dP)0 = 7.8(3), (dG/dP)0 = 2.5(1), (d2KS/dP2)0 = −0.23(3) GPa−...
Article
Using a diamond-anvil cell and synchrotron X-ray diffraction, the compressional behavior of a synthetic ulvöspinel (Fe1.94Ti0.03)Ti1.00O4.00 has been investigated up to about 7.05 GPa at 300 K. The pressure–volume data fitted to the second-order Birch–Murnaghan equation of state yield an isothermal bulk modulus (K T ) of 147(4) GPa (K′ T fixed as 4...
Article
Full-text available
Knowledge of the high-pressure behavior of carbon dioxide (CO2), an important planetary material found in Venus, Earth, and Mars, is vital to the study of the evolution and dynamics of the planetary interiors as well as to the fundamental understanding of the C-O bonding and interaction between the molecules. Recent studies have revealed a number o...
Article
Natural and synthetic pyrope–almandine compositions from 38 to 100 mol% almandine (Alm38–Alm100) were studied by synchrotron X-ray diffraction in the laser-heated diamond anvil cell to 177 GPa. Single-phase orthorhombic GdFeO3-type perovskites were synthesized across the entire examined compositional range at deep lower mantle pressures, with highe...
Article
The influence of Mn content on the stability of the high-pressure CaCO3 phases CaCO3-I, CaCO3-II, and CaCO3-III at 300 K has been investigated up to 40 mol% MnCO3 using Raman spectroscopy recorded in situ with a diamond-anvil cell at pressures up to 14 GPa. Beyond about 5 mol% MnCO3, there is a progressive linear upward shift in the pressure of the...
Article
The formation and properties of the post-perovskite (CaIrO3-type) phase were studied in Fe-rich compositions along the pyrope–almandine ((Mg,Fe)3Al2Si3O12) join. Natural and synthetic garnet starting materials with almandine fractions from 38 to 90 mol% were studied using synchrotron X-ray diffraction in the laser-heated diamond anvil cell. Single-...
Article
Carbon dioxide (CO2) is one of the greenhouse gases that can be readily found in the Earth's atmosphere and possibly inside the Earth. The strength and elasticity study of carbon dioxide (CO2) under high pressures is important to understand the rheological behavior of CO2 that may be relevant to the CO2 storage issue within the Earth and also the e...
Article
Carbon dioxide (CO2) is an important planetary gas phase found in the Venus, Earth and Mars. The high-pressure behavior of CO2 will have important implications for understanding the evolution and dynamics of planetary interiors. CO2 shows six solid phases and one amorphous phase at various pressure and temperature conditions. However, knowledge of...
Article
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Gd3Ga5O12 (GGG), which crystallizes in the garnet structure at ambient conditions, was observed to transform to a high-pressure phase at 88 GPa after laser heating at 1500 K. This new phase is stable at least up to 180 GPa, and can be preserved on decompression to 50 GPa. This phase is cubic and consistent with a perovskite structure of stoichiomet...
Article
The incorporation of the carbonate ion into the crystal structure of hydroxylapatite results in the creation of vacancies, oxygen-loss, and disorder, with consequent changes in physical and chemical properties. High-pressure experimental investigation up to 10 GPa of two synthetic carbonated hydroxylapatite samples with up to 11 wt% CO3, using a di...
Article
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We present a study of charge transfer in Na-intercalated FeOCl and polyaniline-intercalated FeOCl using high-resolution x-ray absorption spectroscopy and resonant x-ray emission spectroscopy at the Fe-K edge. By comparing the experimental data with ab-initio simulations, we are able to unambiguously distinguish the spectral changes which appear due...
Article
BaCrO4 was studied to 25 GPa in a diamond-anvil cell using both Raman spectroscopy and x-ray diffraction methods. Our results showed that BaCrO4 exhibits a phase transition near 9 GPa from both Raman and x-ray diffraction measurements. The new high-pressure phase (BaCrO4-II) is suggested as a monoclinic (P21/m) structure, different from other high-...
Article
Lead bromapatite [Pb10(PO4)6Br2] has been synthesized via solid-state reaction at pressures up to 1.0 GPa, and its structure determined by single-crystal X-ray diffraction at ambient temperature and pressure. The large bromide anion is accommodated in the c-axis channel by lateral displacements of structural elements, particularly of Pb2 cations an...
Article
The structure of lead fluorapatite [PbFAP; Pb10(PO4)6F2], crystallized from the melt in a platinum capsule at 1,000°C and 1 atm, has been investigated by single-crystal X-ray diffraction. Crystal data are a = 9.7638 (6), c = 7.2866 (4) Å, space group P63/m, R = 0.043, R w = 0.034. We have also studied the compressional behaviour of the c-axis chann...
Article
CO2 is an important material in our earth and other planets, studying its high pressure behavior therefore of fundamental significance in understanding planetary evolution and fundamental physics of molecular crystal. In this paper we investigate the high pressure phase transformations of solid CO2 by Raman spectroscopy, laser heating and X-ray dif...
Article
Fe and Al are important elements in Earth's mantle and they may be concentrated in lower mantle chemical heterogeneities associated with subducting slabs, mantle plumes, or core-mantle reaction products. We studied an almandine garnet composition to explore the stability and physical properties of phases in this system at high P-T. Previous multi-a...
Article
Carbon dioxide (CO2) is one of the important planetary materials that can be found in the Venus, Earth and Mars. Therefore, the behavior of CO2 under different pressure and temperature conditions is of great importance for understanding the evolution of these planets. Recent studies showed that there are six solid phases and one amorphous phase of...
Article
Full-text available
The compressional behaviour of a natural kyanite, (Al1.99Fe0.01)SiO5, has been investigated to about 17.5 GPa at 300 K using a diamond-anvil cell and synchrotron X-ray diffraction. The pressure–volume data fitted to the third-order Birch–Murnaghan equation of state (EoS) yield an isothermal bulk modulus (K0T) of 192 ± 6 GPa and pressure derivative...
Article
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The γ-tricalcium phosphate phase (γ-TCP), γ-Ca3(PO4)2, is a high-pressure polymorph of tricalcium phosphate with a potential important implication as the reservoir of rare-earth elements and very large lithophile elements in the deep mantle. In situ synchrotron X-ray diffraction measurements of the γ-TCP phase have been carried out using a diamond-...
Article
Phases D and E are hydrous magnesium silicates that are stable at high-pressure-temperature conditions and could serve as H2O carriers in the Earth's mantle, especially in subducting slabs. Using synchrotron infrared (IR) spectroscopy, we measured the infrared spectra of polycrystalline samples of phases D and E to 42 and 41 GPa, respectively. For...
Article
Earth consists of multiphase materials and therefore knowledge of the plastic and elastic properties of the multiphase aggregates under high pressures is of central importance for understanding dynamic processes within the Earth. Interpretation of static high-pressure experiments also requires knowledge of mixtures and composite materials. We have...
Article
To evaluate the iron and aluminum effects on the post-perovskite phase at deep mantle conditions, it is important to study the potential mantle silicates containing both iron and aluminum. In this study, three different compositions of natural garnet along pyrope-almandine join, Pyr21Alm73Gr5, Pyr43Alm54Gr2, Pyr58Alm38Gr3, were used as starting mat...
Article
Fe and Al are two of the most abundant minor elements in the lower mantle and may have significant effects on the stability and elastic properties of the region's dominant phase, MgSiO3 perovskite. In order to predict the chemical and physical behavior of lower mantle chemical heterogeneities enriched in Fe and Al, we investigated perovskites synth...
Article
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The pressure-induced valence transition in TmTe was investigated by resonant inelastic x-ray scattering at the Tm L3 edge, a powerful probe of the rare-earth valent state. The data are analyzed within the Anderson impurity model which yields key parameters such as the Tm 4f-5d hybridization. In addition to the general tendency of the f electrons to...
Article
The compressional behavior of a synthetic lead fluorapatite [Pb9.35(PO4)6F2] has been investigated in situ up to about 16.7 GPa at 300 K, using a diamond-anvil cell and synchrotron X-ray diffraction. We find that the compressibility of lead fluorapatite is significantly different from that of fluorapatite [Ca10(PO4)6F2], chlorapatite [Ca10(PO4)6Cl2...
Article
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The effect of iron on the post-perovskite phase transition has been controversial. We have performed direct chemical analyses of co-existing perovskite and post-perovskite that were synthesized from an (Mg{sub 0.91}Fe{sub 0.09})SiOâ bulk composition using a laser-heated diamond anvil cell at pressures above 100 GPa and temperatures of 1700-1800 K....
Article
The post-perovskite phase could be the dominant phase at the core-mantle boundary and may be responsible for the anomalous seismic discontinuities within and across the D" layer. However, the chemical complexity and extreme conditions near the core-mantle region may strongly affect the structure and stability field of post- perovskite phase. To und...