Amorphization and Molecular Dissociation of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>Sn</mml:mi><mml:mrow><mml:msub><mml:mrow><mml:mi>I</mml:mi></mml:mrow><mml:mrow><mml:mn>4</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>at High Pressure

Hamaya, Nozomu; Sato, K.; Usui-Watanabe, K.; Fuchizaki, Kazuhiro; Fujii, Yasuhiko; Ohishi, Yasuo

doi:10.1103/physrevlett.79.4597

Cited by 56 publications

(34 citation statements)

References 20 publications

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“…13 Furthermore, another amorphous state ͑Am-II͒ was found during decompression from Am-I. 13 More precise investigation revealed that the transition between the low-pressure amorphous state, Am-II, and the high-pressure modification, Am-I, 14 is reversible, and the existence limits of Am-II and Am-I are 7 GPa ͑open square in Fig.…”

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confidence: 99%

Polyamorphism in tin tetraiodide

Fuchizaki

Hase

Yamada

et al. 2009

The Journal of Chemical Physics

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The discovery of a first-order phase transition in fluid phosphorus aroused renewed interest in polyamorphism in liquids with a locally tetrahedral molecular structure. We have performed in situ synchrotron x-ray diffraction measurements on tin tetraiodide, which consists of SnI4 tetrahedral molecules at ambient pressure, and established that the liquid forms existing above and below 1.5 GPa, where the slope of the melting curve of the solid phase changes abruptly, have different structures. This discovery offers evidence of thermodynamically stable polyamorphism in general compounds as well as in elements. A possible phase diagram that includes the two amorphous states already found is proposed based on the pseudobinary regular solution model. The vertex-to-face orientation between the nearest molecules plays a key role in the transition from the low-pressure to the high-pressure liquid phase.

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confidence: 99%

Polyamorphism in tin tetraiodide

Fuchizaki

Hase

Yamada

et al. 2009

The Journal of Chemical Physics

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“…A simple first-shell model accounting for the first peak of the radial distribution was used to fit the experimental data. We considered only two-body first-neighbor signals (γ (2) ), due to the single scattering between the Ge-Ge and SiGe pairs, assuming a Gaussian bond-length distribution (upper green curves in Fig. 7).…”

Section: B Xas Analysis: Edge Shift and Local Structurementioning

confidence: 99%

“…Disordered matter under extreme conditions of pressure and temperature can exhibit structural changes whose nature is not completely understood. An external pressurization can result in the atomic rearrangement into crystalline and nano-crystalline structures (pressure-induced crystallization, [1][2][3][4] ), thus opening the way to the study of new phases and metastable states. Compressed amorphous materials also show complex transformation during the pressure release, including the stabilization of new crystalline structures as well as the recover of the initial amorphous one [5][6][7][8] .…”

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confidence: 99%

Pressure-induced transformations in amorphous Si-Ge alloy

et al. 2012

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The pressure behavior of an amorphous Si-rich SiGe alloy (a-SixGe1−x, x=0.75) has been investigated up to about 30 GPa, by a combination of Raman spectroscopy, x-ray absorption spectroscopy and x-ray diffraction measurements. The trends of microscopic structural properties and of the Raman-active phonon modes are presented in the whole pressure range. Nucleation of nanocrystalline alloy particles and metallization have been observed above 12 GPa, with a range of about 2 GPa of coexistence of amorphous and crystalline phases. Transformations from the amorphous tetrahedral, to the crystalline tetragonal (β-Sn) and to the simple hexagonal structures have been observed around 13.8 GPa and 21.8 GPa. The recovered sample upon depressurization, below about 4 GPa, shows a local structure similar to the as-deposited one. Inhomogeneities of the amorphous texture at the nanometric scale, probed by high resolution transmission electron microscopy, indicate that the recovered amorphous sample has a different ordering at this scale, and therefore the transformations can not be considered fully reversible. The role of disordered grain boundaries at high pressure and the possible presence of a high-density amorphous phase are discussed.

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“…1 A phase diagram was proposed on the basis of the pseudo-binary regular-solution (pBRS) model. 2 That is, among four possible scenarios, 3 the liquid-liquid critical point (LLCP) scenario, 4 which could quite naturally explain the relation between the two liquid states and the low-density amorphous (LDA) and high-density amorphous (HDA) states discovered earlier, 5 was chosen. In constructing the phase diagram, we assumed that the critical-point (CP) pressure, p c , is 0.5 GPa.…”

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confidence: 99%

“…The extra input was the melting temperature, 417 K, of CP-I at ambient pressure, and the point, 5.22 GPa and 932 K, on the melting curve of CP-I, the point being assumed as another triple point at which Liq-I, CP-I, and another crystalline phase meet. The third one might be CP-II, 5 or its high-temperature modification, not yet identified. 15 We also assumed that the slope of the melting curve of this latter crystalline phase is ∼40 K GPa −1 .…”

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confidence: 99%

Communication: Probable scenario of the liquid–liquid phase transition of SnI4

Fuchizaki

Hamaya

Hase³

et al. 2011

The Journal of Chemical Physics

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We have shown from in situ synchrotron x-ray diffraction measurements that there are two thermodynamically stable liquid forms of SnI4, depending on the pressure. Based on the liquid–liquid critical point scenario, our recent measurements suggest that the second critical point, if it exists, may be located in a region close to the point at which the melting curve of the crystalline phase abruptly breaks. This region is, unlike that of water, experimentally accessible with relative ease.

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Amorphization and Molecular Dissociation ofSnI4at High Pressure

Cited by 56 publications

References 20 publications

Polyamorphism in tin tetraiodide

Polyamorphism in tin tetraiodide

Pressure-induced transformations in amorphous Si-Ge alloy

Communication: Probable scenario of the liquid–liquid phase transition of SnI4

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