Degree of Permanent Densification in Oxide Glasses upon Extreme Compression up to 24 GPa at Room Temperature

Lee, Sung Keun; Mun, Kwan Young; Kim, Yong-Hyun; Lhee, Juho; Okuchi, Takuo; Lin, Jung Fu

doi:10.1021/acs.jpclett.0c00709

Cited by 25 publications

(41 citation statements)

References 72 publications

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“…Note that it is difficult to determine the phase transition temperature under ºC, because the phase transformation in the low-temperature range can be kinetically broadened (e.g., Lee et al, 2020). Thus, further extensive study for kinetic nature of dehydration is necessary.…”

Section: Quantification Of Coexisting Phases In the Heat-treated Alummentioning

confidence: 99%

Probing the transformation paths from aluminum (oxy)hydroxides (boehmite, bayerite, and gibbsite) to metastable alumina: A view from high-resolution 27Al MAS NMR

Kim

Lee

2021

American Mineralogist

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Detailed knowledge of the structural evolution of diverse aluminum (oxy)hydroxides with varying temperatures up to ~300 °C provides insights into the dehydration processes involving transitions among metastable phases in Earth's surface and crust. Here, we report the high-resolution solid-state 27 Al NMR spectra for three different types of aluminum (oxy)hydroxides (i.e., boehmite, bayerite, and gibbsite) with varying annealing temperatures up to 300 °C, revealing the effect of distinct precursor minerals on the stability of metastable alumina. 27 Al MAS NMR results allow us to obtain the quantitative fractions and NMR parameters for each phase during transformation. The results demonstrate that each aluminum (oxy)hydroxide phase follows the unique transformation path to metastable alumina. The 27 Al MAS and 3QMAS NMR spectra of boehmite show that a minor but observable [4] Al signal (~2%) is detected at ~50 °C, and the [4] Al fraction gradually increases up to 300 °C (~16%), indicating that the phase transformation from boehmite to -/-Al 2 O 3 occurs at a temperature as low as ~50 °C, significantly lower than earlier estimations based on XRD. Together with the [4] Al fraction, the [5] Al fraction increases from < 1% at 50 °C to ~2.3% at 300 °C, whereas the NMR results of bayerite and gibbsite do not show the presence of [5] Al. In addition, the 27 Al 3QMAS NMR spectra resolved the [6] Al site in boehmite and that in -/-Al 2 O 3 , which could not be uniquely determined from 1D NMR spectra. The population of bayerite abruptly decreases from 100% (at 150 ºC), through ~47% (at 200 ºC), to 0% (at 250 ºC), indicating that the phase transition from bayerite to boehmite + -/-Al 2 O 3 occurs within a narrow temperature range. As for gibbsite, while [4] Al is not observed in the spectra up to 200 °C, the [4] Al fraction of ~2% is observed in the spectra for gibbsite annealed at 250 °C, and the [4] Al fraction increases rapidly to ~15% as the annealing temperature increases to 300 °C, suggesting that the phase transformation into -/-Al2O3 occurs at ~250 ºC. The results confirm that the phase transformation paths (gradual vs. dramatic) depend on the type of precursor minerals. Particularly, the threshold temperature at which the onset of the phase transformation from boehmite to metastable alumina (~50 ºC) is lower than those from other precursor minerals (>150 ºC). Furthermore, the phase transformation from boehmite to -/-Al 2 O 3 occurs gradually within broad temperature ranges from ~50 °C. This is due to This is the peer-reviewed, final accepted version for American Mineralogist, published by the Mineralogical Society of America. The published version is subject to change. Cite as Authors (Year) Title. American Mineralogist, in press.

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Section: Quantification Of Coexisting Phases In the Heat-treated Alummentioning

confidence: 99%

Probing the transformation paths from aluminum (oxy)hydroxides (boehmite, bayerite, and gibbsite) to metastable alumina: A view from high-resolution 27Al MAS NMR

Kim

Lee

2021

American Mineralogist

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“…Such manipulation of the ordering changes the glass properties, but unlike crystalline solids where symmetry rules, characterizing the nature of this order remains an open challenge. Consequently, there is a structure-versusproperties puzzle in need of a solution for understanding basic issues such as the structural precursors for crystallization in glass 2 and the mechanisms of densification [3][4][5] for guiding the development of new technological materials [6][7][8] .…”

Section: Introductionmentioning

confidence: 99%

Structure and properties of densified silica glass: characterizing the order within disorder

et al. 2020

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The broken symmetry in the atomic-scale ordering of glassy versus crystalline solids leads to a daunting challenge to provide suitable metrics for describing the order within disorder, especially on length scales beyond the nearest neighbor that are characterized by rich structural complexity. Here, we address this challenge for silica, a canonical network-forming glass, by using hot versus cold compression to (i) systematically increase the structural ordering after densification and (ii) prepare two glasses with the same high-density but contrasting structures. The structure was measured by high-energy X-ray and neutron diffraction, and atomistic models were generated that reproduce the experimental results. The vibrational and thermodynamic properties of the glasses were probed by using inelastic neutron scattering and calorimetry, respectively. Traditional measures of amorphous structures show relatively subtle changes upon compacting the glass. The method of persistent homology identifies, however, distinct features in the network topology that change as the initially open structure of the glass is collapsed. The results for the same high-density glasses show that the nature of structural disorder does impact the heat capacity and boson peak in the low-frequency dynamical spectra. Densification is discussed in terms of the loss of locally favored tetrahedral structures comprising oxygen-decorated SiSi4 tetrahedra.

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“…The network structure including highly coordinated cations (ie, Al 3+ and Si 4+ ) becomes flexible due to the increase in ionicity of the bonds. In actuality, softening of glass and melt induced by the coordination increase, which is more markedly observed in Mg‐aluminosilicate glasses, 18,19 has been reported in previous studies 14,15 . Highly coordinated Al in MAS may enhance the structural modification during deformation.…”

Section: Resultsmentioning

confidence: 63%

Transition in deformation mechanism of aluminosilicate glass at high pressure and room temperature

et al. 2020

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Deformation experiments for 20(MgO or Na 2 O)-20Al 2 O 3-60SiO 2 glasses were performed in simple shear geometry at 1.5-5 GPa and room temperature. An abrupt change in the thinning rate and the turning of the birefringence azimuth at a shear strain of γ = 1-2 indicate a transition of deformation mechanism from uniaxial compression aided by densification to shear flow in the glasses. The high-dense magne-How to cite this article: Osada K, Yamada A, Ohuchi T, Yoshida S, Matsuoka J. Transition in deformation mechanism of aluminosilicate glass at high pressure and room temperature.

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Degree of Permanent Densification in Oxide Glasses upon Extreme Compression up to 24 GPa at Room Temperature

Cited by 25 publications

References 72 publications

Probing the transformation paths from aluminum (oxy)hydroxides (boehmite, bayerite, and gibbsite) to metastable alumina: A view from high-resolution 27Al MAS NMR

Probing the transformation paths from aluminum (oxy)hydroxides (boehmite, bayerite, and gibbsite) to metastable alumina: A view from high-resolution 27Al MAS NMR

Structure and properties of densified silica glass: characterizing the order within disorder

Transition in deformation mechanism of aluminosilicate glass at high pressure and room temperature

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