Pressure-induced amorphization of minerals: a review

Richet, Pascal; Gillet, Philippe

doi:10.1127/ejm/9/5/0907

Cited by 169 publications

(130 citation statements)

References 109 publications

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“…At high pressure many materials exhibit structural phase transitions, while some become amorphous [1][2][3][4][5][6][7]. Although it is widely believed that the phenomenon of pressure-induced amorphization (PIA) arises due to kinetic hindrance of equilibrium phase transitions, the structure of the equilibrium high-pressure phase, which the compound should have ideally evolved to, has remained speculative or unknown in most cases.…”

Section: Introductionmentioning

confidence: 99%

The pressure-amorphized state in zirconium tungstate: a precursor to decomposition

Arora¹,

Sastry²,

Sahu³

et al. 2004

J. Phys.: Condens. Matter

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In contrast to widely accepted view that pressure-induced amorphization arises due to kinetic hindrance of equilibrium phase transitions, here we provide evidence that the metastable pressure-amorphized state in zirconium tungstate is a precursor to decomposition of the compound into a mixture of simple oxides. This is from the volume collapse V across amorphization, which is obtained for the first time by measuring linear dimensions of irreversibly amorphized samples during their recovery to the original cubic phase upon isochronal annealing up to 1000 K. The anomalously large V of 25.7 ± 1.2% being the same as that expected for the decomposition indicates that this amorphous state is probably a precursor to kinetically hindered decomposition. A P-T diagram of the compound is also proposed.

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Section: Introductionmentioning

confidence: 99%

The pressure-amorphized state in zirconium tungstate: a precursor to decomposition

Arora¹,

Sastry²,

Sahu³

et al. 2004

J. Phys.: Condens. Matter

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“…The compression of zeolites using non-penetrating media has also been exploited to induce the so-called ''pressureinduced amorphization'' (PIA). [26][27][28][29][30][31][32][33][34][35][36][37][38] PIA is observed for a wide range of silicate structures and is accompanied by significant volume reductions, resulting in a new denser material. For some zeolites, PIA is irreversible in the presence of small extraframework cations (e.g.…”

Section: Introductionmentioning

confidence: 99%

Pressure-induced penetration of guest molecules in high-silica zeolites: the case of mordenite

Arletti

Leardini

Vezzalini

et al. 2015

Phys. Chem. Chem. Phys.

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A synthetic high-silica mordenite (HS-MOR) has been compressed in both non-penetrating (silicone oil, s.o.) and penetrating [methanol : ethanol : water (16 : 3 : 1) (m.e.w.), water : ethanol (3 : 1) (w.e.), and ethylene glycol (e.gl.)] pressure transmitting media (PTM). In situ high-pressure (HP) synchrotron X-ray powder diffraction (XRPD) experiments allowed the unit cell parameters to be followed up to 1.6, 1.8, 8.4, and 6.7 GPa in s.o., w.e., m.e.w., and e.gl., respectively. Moreover, e.gl. was also used as a PTM in in situ HP Raman and ex situ IR experiments. The structural refinement of HS-MOR compressed in e.gl.at 0.1 GPa -the lowest investigated pressure -revealed the presence of 3.5 ethylene glycol molecules per unit cell. The infrared spectrum of the recovered sample, after compression to 1 GPa, is consistent with the insertion of ethylene glycol molecules in the pores. XRPD and Raman spectroscopy experiments performed under pressure indicated the insertion of a small number of guest molecules. Ethylene glycol is partially retained inside mordenite upon pressure release. A symmetry lowering was observed in s.o. above 0.8 GPa, while above 1.6 GPa the patterns indicated a rapid loss of long range order. From ambient pressure (P amb ) to 1.6 GPa, a high cell volume contraction (DV = À9.5%) was determined. The patterns collected with penetrating PTM suggested the penetration of guest molecules into the porous host matrix, starting from a very low P regime. The entrapment of PTM molecules inside micropores contributes to the stiffening of the structure and, as a consequence, to the decrease of the compressibility with respect to that measured in s.o. From the structural point of view, HS-MOR reacts to compression and to the penetration of different guest species with appropriate framework deformations. Interestingly, ethylene glycol is partially retained inside mordenite upon pressure release, which is of importance for potential application of this composite material.

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“…Many minerals can be turned amorphous by mere application of pressure, a phenomenon known as pressureinduced amorphization (PIA) [1]. Our understanding of PIA is only partial.…”

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confidence: 99%

Amorphization Induced by Pressure: Results for Zeolites and General Implications

Peral

Íñiguez

2006

Phys. Rev. Lett.

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We report an ab initio study of pressure-induced amorphization (PIA) in zeolites, which are model systems for this phenomenon. We confirm the occurrence of recently reported low-density amorphous phases that preserve the crystalline topology, and explain the role of the zeolite composition regarding PIA. Our results support the correctness of existing models for the basic PIA mechanism, but suggest that energetic, rather than kinetic, factors determine the irreversibility of the transition. In such a transition, domain nucleation would overwhelm growth and destroy the long-range order [5]. Cohen, Íñiguez, and Neaton [5] (CIN) further propose the PIA transition will be reversible (i.e., the long-range order will be recovered upon decompression) if the crystalline topology (i.e., the atomic coordination and bonding) is preserved in the amorphous phase.Recent work [6] on the nanoporous aluminosilicates known as zeolites has renewed the interest in PIA. It was shown that a zeolite may present two distinct PIA phases: a low-pressure ( 2 GPa) low-density amorphous phase (LDA), which might constitute a ''perfect'' glass with negligible configuration entropy, and a high-pressure ( 6 GPa) high-density amorphous phase (HDA). Further, the crystalline topology is found to be preserved in the LDA phase and lost in the HDA phase, which, according to the CIN picture, implies amorphization will be reversible in the former case and irreversible in the latter. These results, together with other studies [7,8] that, for example, show a striking dependence of the PIA reversibility on the zeolite composition, clearly point at these systems as ideal to test general PIA theories.Here we report an ab initio study that reveals the mechanisms controlling PIA in zeolites and provides important insights pertaining PIA phenomena at large.We used the generalized gradient approximation (GGA) to density functional theory [9] as implemented in the code SIESTA [10]. We wanted to study amorphization occurring in spite of negligible thermal activation and thus focused on low temperature simulations. We proceeded as follows: we started from the experimentally known zero-pressure phase and increased (or decreased) the pressure p by a p of 0.25 GPa. At each new pressure p p, we started from the structure obtained for the previous pressure p, performed a short (100 fs) molecular dynamics simulation at 100 K, with random initial velocities, and relaxed the resulting structure. In this way, we were able to compute the pressure dependence of a phase up to its (meta)stability limit, where it transforms into a new phase that is directly obtained from the calculation. Discontinuities in the calculated volume=enthalpy are indicative of first-order transitions; when the discontinuities appear only in the slope of the volume/enthalpy versus pressure curve, the transitions are of second-order.Zeolites have the general formula A n x=n Al x Si 1ÿx O 2 , where A is a charge-compensating cation. The Si=Al atoms are at the center of corner-sharing O 4 tetrahedra. A...

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Pressure-induced amorphization of minerals: a review

Cited by 169 publications

References 109 publications

The pressure-amorphized state in zirconium tungstate: a precursor to decomposition

The pressure-amorphized state in zirconium tungstate: a precursor to decomposition

Pressure-induced penetration of guest molecules in high-silica zeolites: the case of mordenite

Amorphization Induced by Pressure: Results for Zeolites and General Implications

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