Atomistic pathways of the pressure-induced densification of quartz

Liang, Yunfeng; Miranda, Caetano R.; Scandolo, Sandro

doi:10.1103/physrevb.92.134102

Cited by 6 publications

(10 citation statements)

References 43 publications

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“…The newly formed phase after lattice collapse has a C222 structure where anions form a close-packed b.c.c-like sublattice and one-third of cations occupy the tetrahedral sites of O atoms and two-thirds of the cations occupy the octahedral sites. This same post-quartz phase has been previously predicted to form [8,21,27,54], but our results reveal that this displacive phase transition occurred at a much higher pressure (above 48 GPa).…”

Section: Resultssupporting

confidence: 88%

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Stability limits and transformation pathways ofα-quartz under high pressure

Shu

Yang

et al. 2017

Phys. Rev. B

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Ubiquitous on Earth, α-quartz plays an important role in modern science and technology. However, despite extensive research in the past, the mechanism of the polymorphic transitions of α-quartz at high pressures remains poorly understood. Here, combining in situ single-crystal xray diffraction experiment and advanced ab initio modeling, we report two stability limits and competing transition pathways of α-quartz under high pressure. Under near-equilibrium compression conditions at room temperature, α-quartz transits to a new P2/c silica phase, via a structural intermediate. If the thermally activated transition is kinetically suppressed, the ultimate stability of α-quartz is controlled by its phonon instability and α-quartz collapses into a different crystalline phase. Our studies reveal that pressure-induced solid-state transformation of α-quartz undergoes a succession of structural stability limits due to thermodynamic and mechanical catastrophes, and exhibits a hierarchy of transition pathways contingent upon kinetic conditions.

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Section: Resultssupporting

confidence: 88%

“…Silica is among the most common materials in nature and possesses tremendous technological importance [1][2][3][4][5][6][7][8]. A plethora of crystal structures, including crystals and amorphous solids exist in the SiO 2 system at different pressure and temperature conditions [9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Stability limits and transformation pathways ofα-quartz under high pressure

Shu

Yang

et al. 2017

Phys. Rev. B

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“…The unusual pressure-induced amorphization phenomenon has been studied for about 30 y (16,43); however, recent experiments have added some insights (and doubts) on the amorphous structure by a conception on the basis of coexistence of the low-symmetry crystalline phases. However, as it is shown here and also in our previous work on quartz (32), a completely disordered phase can be obtained. The arrangement of O atoms in hcp sublattice is very important to describe the high-pressure silica polymorphs.…”

Section: Discussionsupporting

confidence: 83%

“…As pressure increases, both α-quartz and α-cristobalite transform into high-pressure structures with body-centered cubic (bcc) oxygen sublattice (27,32,40,41). However, as shown in SI Appendix, Fig.…”

Section: Discussionmentioning

confidence: 99%

Multiple pathways in pressure-induced phase transition of coesite

Liu

Liang

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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High-pressure single-crystal X-ray diffraction method with precise control of hydrostatic conditions, typically with helium or neon as the pressure-transmitting medium, has significantly changed our view on what happens with low-density silica phases under pressure. Coesite is a prototype material for pressure-induced amorphization. However, it was found to transform into a high-pressure octahedral (HPO) phase, or coesite-II and coesite-III. Given that the pressure is believed to be hydrostatic in two recent experiments, the different transformation pathways are striking. Based on molecular dynamic simulations with an ab initio parameterized potential, we reproduced all of the above experiments in three transformation pathways, including the one leading to an HPO phase. This octahedral phase has an oxygen hcp sublattice featuring 2 × 2 zigzag octahedral edge-sharing chains, however with some broken points (i.e., point defects). It transforms into α-PbO phase when it is relaxed under further compression. We show that the HPO phase forms through a continuous rearrangement of the oxygen sublattice toward hcp arrangement. The high-pressure amorphous phases can be described by an fcc and hcp sublattice mixture.

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“…The pathways between structures can be broken down into sets of transformations involving some combinations of displacive and ordering mechanisms. In recent years, new studies have revisited this subject with various phenomenological approaches including excited-state transition pathway calculations and ab initio molecular dynamics ( 9 , 10 , 30 ). These simulations suggest that under nonhydrostatic conditions, the quasi–body-centered cubic oxygen sublattice that describes α-quartz can transform via a martensitic mechanism (Burgers path) to an hcp oxygen lattice ( 9 , 38 ).…”

Section: Discussionmentioning

confidence: 99%

Structural response of α-quartz under plate-impact shock compression

2020

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Because of its far-reaching applications in geophysics and materials science, quartz has been one of the most extensively examined materials under dynamic compression. Despite 50 years of active research, questions remain concerning the structure and transformation of SiO2 under shock compression. Continuum gas-gun studies have established that under shock loading quartz transforms through an assumed mixed-phase region to a dense high-pressure phase. While it has often been assumed that this high-pressure phase corresponds to the stishovite structure observed in static experiments, there have been no crystal structure data confirming this. In this study, we use gas-gun shock compression coupled with in situ synchrotron x-ray diffraction to interrogate the crystal structure of shock-compressed α-quartz up to 65 GPa. Our results reveal that α-quartz undergoes a phase transformation to a disordered metastable phase as opposed to crystalline stishovite or an amorphous structure, challenging long-standing assumptions about the dynamic response of this fundamental material.

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Atomistic pathways of the pressure-induced densification of quartz

Cited by 6 publications

References 43 publications

Stability limits and transformation pathways ofα-quartz under high pressure

Stability limits and transformation pathways ofα-quartz under high pressure

Multiple pathways in pressure-induced phase transition of coesite

Structural response of α-quartz under plate-impact shock compression

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