Electronic, Structural, and Mechanical Properties of 
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 Glass at High Pressure Inferred from its Refractive Index

Lobanov, Sergey S.; Speziale, S.; Winkler, Björn; Milman, Victor; Refson, Keith; Schifferle, Lukas

doi:10.1103/physrevlett.128.077403

Cited by 7 publications

(13 citation statements)

References 85 publications

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“…The flat tips of diamond anvils form an interferometer; thus, the distance between the anvils can be measured directly by analyzing the interference pattern in the spectrum of a reflected (or transmitted) white light if the refractive index of the sample is known (Dewaele et al., 2003; Kim et al., 2021). Here we apply a recently developed approach (Lobanov et al., 2022) to measure the diamond‐to‐diamond separation upon compression up to ∼135 GPa ( P at the CMB) and subsequent decompression. Briefly, our approach involves reflecting a broadband laser probe from the diamond‐sample‐diamond assemblage and recording the reflected signal on a charge‐coupled device.…”

Section: Methodsmentioning

confidence: 99%

“…The sample thickness ( l ) is then obtained from the spectral separation of the observed extrema which yields the optical path length ( n 600nm l ) under the assumption that index dispersion in the measured spectral range is small. The overall uncertainty in l is ∼1% (Lobanov et al., 2022).…”

Section: Methodsmentioning

confidence: 99%

“…See Lobanov et al. (2022) for graphical definitions of the measured quantities. The gray box depicts the spectral range used for averaging the signal to obtain the refractive index at 600 nm ( n 600nm ).…”

Section: Methodsmentioning

confidence: 99%

“…Here we apply a recently developed approach (Lobanov et al, 2022) to measure the diamond-to-diamond separation upon compression up to ∼135 GPa (P at the CMB) and subsequent decompression. Briefly, our approach involves reflecting a broadband laser probe from the diamond-sample-diamond assemblage and recording the reflected signal on a charge-coupled device.…”

Section: Methodsmentioning

confidence: 99%

“…Intensity ratio spectra ((I 1 + I 2 )/I 0 ) measured in KCl at 84.5 GPa at the center of the diamond anvil cell (DAC) cavity and ∼5 μm off the center. See Lobanov et al (2022) for graphical definitions of the measured quantities. The gray box depicts the spectral range used for averaging the signal to obtain the refractive index at 600 nm (n 600nm ).…”

Section: Methodsmentioning

confidence: 99%

See 4 more Smart Citations

Non‐Isotropic Contraction and Expansion of Samples in Diamond Anvil Cells: Implications for Thermal Conductivity at the Core‐Mantle Boundary

Lobanov

Geballe

2022

Geophysical Research Letters

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The thermal conductivities of mantle and core materials have a major impact on planetary evolution, but their experimental determination requires precise knowledge of sample thickness at high pressure. Despite its importance, thickness in most diamond anvil cell (DAC) experiments is not measured but inferred from equations of state, assuming isotropic contraction upon compression or assuming isotropic expansion upon decompression. Here we provide evidence that in DAC experiments both assumptions are invalid for a range of mechanically diverse materials (KCl, NaCl, Ar, MgO, silica glass, Al2O3). Upon compression, these samples are ∼30–50% thinner than expected from isotropic contraction. Most surprisingly, all the studied samples continue to thin upon decompression to 10–20 GPa. Our results partially explain some discrepancies among the highly controversial thermal conductivity values of iron at Earth's core conditions. More generally, we suggest that in situ characterization of sample geometry is essential for conductivity measurements at high pressure.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 3 more Smart Citations

Non‐Isotropic Contraction and Expansion of Samples in Diamond Anvil Cells: Implications for Thermal Conductivity at the Core‐Mantle Boundary

Lobanov

Geballe

2022

Geophysical Research Letters

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Pathway for a martensitic quartz–coesite transition

Schaffrinna,

Milman,

Winkler

2024

Sci Rep

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An atomistic pathway for a strain-induced subsolidus martensitic transition between quartz and coesite was found by computing the set of the smallest atomic displacements required to transform a quartz structure into a coesite structure. A minimal transformation cell with 24 $${\hbox {SiO}_{2}}$$ SiO 2 formula units is sufficient to describe the diffusionless martensitic transition from quartz to coesite. We identified two families of invariant shear planes during the martensitic transition, near the {10$${\bar{1}}$$ 1 ¯ 1} and {12$${\bar{3}}$$ 3 ¯ 2} set of planes, in agreement with the orientation of planar defect structures observed in quartz samples which experienced hypervelocity impacts. We calculated the reaction barrier using density functional theory and found that the barrier of 150 meV/atom is pressure invariant from ambient pressure up to 5 GPa, while the mean principal stress limiting the stability of strained quartz is $$\approx$$ ≈ 2 GPa. The model calculations quantitatively confirm that coesite can be formed in strained quartz at pressures significantly below the hydrostatic equilibrium transition pressure.

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High-pressure evolution of the refractive index of MgO up to 140 GPa

Schifferle

Speziale

Lobanov

2022

Journal of Applied Physics

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Refractive index provides fundamental insights into the electronic structure of materials. At high pressure, however, the determination of refractive index and its wavelength dispersion is challenging, which limits our understanding of how physical properties of even simple materials, such as MgO, evolve with pressure. Here, we report on the measurement of room-temperature refractive index of MgO up to ∼140 GPa. The refractive index of MgO at 600 nm decreases by ∼2.4% from ∼1.737 at 1 atm to ∼1.696 (±0.017) at ∼140 GPa. Despite the index at 600 nm is essentially pressure independent, the absolute wavelength dispersion of the refractive index at 550–870 nm decreases by ∼28% from ∼0.015 at 1 atm to ∼0.011 (±8.04 × 10−4) at ∼103 GPa. Single-effective-oscillator analysis of our refractive index data suggests that the bandgap of MgO increases by ∼1.1 eV from 7.4 eV at 1 atm to ∼8.5 (±0.6) eV at ∼103 GPa.

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Electronic, Structural, and Mechanical Properties of SiO2 Glass at High Pressure Inferred from its Refractive Index

Cited by 7 publications

References 85 publications

Non‐Isotropic Contraction and Expansion of Samples in Diamond Anvil Cells: Implications for Thermal Conductivity at the Core‐Mantle Boundary

Non‐Isotropic Contraction and Expansion of Samples in Diamond Anvil Cells: Implications for Thermal Conductivity at the Core‐Mantle Boundary

Pathway for a martensitic quartz–coesite transition

High-pressure evolution of the refractive index of MgO up to 140 GPa

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