Pressure-induced amorphous phases

Ponyatovsky, E.G.; Belash, I. T.; Barkalov, O. I.

doi:10.1016/0022-3093(90)90621-r

Cited by 50 publications

(34 citation statements)

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“…Here we report compression experiments on ®lms of porous Si, which contains nanometre-sized domains of diamondstructured material 7±9 . At pressures larger than 10 GPa we observed pressure-induced amorphization 10,11 . Furthermore, we ®nd from Raman spectroscopy measurements that the highdensity amorphous form obtained by this process transforms to low-density amorphous silicon upon decompression.…”

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confidence: 90%

“…Two-state models used to describe liquids that exhibit melting-curve maxima or negative melting slopes consider mixing of species with low and high coordination 16 . Application of regular solution thermodynamics to the mixing reveals a critical point, below which ®rst-order transitions occur between low-and high-density liquid (LDL and HDL) phases: that is, the liquid-state behaviour passes from twostate to two-phase 10 . A recent model considers bond-excitation processes rather than distinct structural species to describe the liquid structure 21 .…”

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confidence: 99%

“…liquid±liquid phase transitions 10,14,15 . Two-state models used to describe liquids that exhibit melting-curve maxima or negative melting slopes consider mixing of species with low and high coordination 16 .…”

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confidence: 99%

“…Our observations indicate that pressure-induced amorphization (PIA) of crystalline Si has occurred in the sample. PIA has been reported for many materials, including III-V semiconductorsÐbut not for Si, in which recrystallization is usually rapid even at ambient temperature 10,11 . We found no evidence for appearance of dense crystalline phases of Si on compression in excess of 10 GPa, unlike the behaviour observed for bulk material or surface-terminated nanocrystalline particles 5,6 .…”

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Pressure-induced amorphization and an amorphous–amorphous transition in densified porous silicon

Deb

Wilding

Somayazulu

et al. 2001

Nature

385

291

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Crystalline and amorphous forms of silicon are the principal materials used for solid-state electronics and photovoltaics technologies. Silicon is therefore a well-studied material, although new structures and properties are still being discovered. Compression of bulk silicon, which is tetrahedrally coordinated at atmospheric pressure, results in a transition to octahedrally coordinated metallic phases. In compressed nanocrystalline Si particles, the initial diamond structure persists to higher pressure than for bulk material, before transforming to high-density crystals. Here we report compression experiments on films of porous Si, which contains nanometre-sized domains of diamond-structured material. At pressures larger than 10 GPa we observed pressure-induced amorphization. Furthermore, we find from Raman spectroscopy measurements that the high-density amorphous form obtained by this process transforms to low-density amorphous silicon upon decompression. This amorphous-amorphous transition is remarkably similar to that reported previously for water, which suggests an underlying transition between a high-density and a low-density liquid phase in supercooled Si (refs 10, 14, 15). The Si melting temperature decreases with increasing pressure, and the crystalline semiconductor melts to a metallic liquid with average coordination approximately 5 (ref. 16).

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confidence: 99%

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Pressure-induced amorphization and an amorphous–amorphous transition in densified porous silicon

Deb

Wilding

Somayazulu

et al. 2001

Nature

385

291

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“…It has been extensively investigated because of the metastable phase during solidification. The phase has an excellent performance in superconductivity [1][2][3]. McAlister and Murray [4] collected a lot of research results at an earlier stage.…”

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Structure correlation of Al71.6Ge28.4 eutectic alloy between liquid and solid states

et al. 2010

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The liquid structure of Al 71.6 Ge 28.4 eutectic alloy was studied by X-ray diffractometer. For the liquid alloy Al 71.6 Ge 28.4 , the structure has no change while the order increases with the decreasing temperature from 1150°C to 550°C. Meanwhile, the correlation between liquid structure and solid structure has also been analyzed by "the nanocrystal model". It is shown that the melt consists of 72.8% α clusters and 27.2% β clusters, but the liquid structure and solid structure have striking difference, which is one of the reasons to obtain a large undercooling easily for this alloy. liquid structure, X-ray diffraction, nanocrystal model, liquid-solid correlation, undercooling Citation: Sun J J, Tian X L, Zhan C W, et al. Structure correlation of Al 71.6 Ge 28.4 eutectic alloy between liquid and solid state.The Al-Ge alloy is a simple eutectic system. It has been extensively investigated because of the metastable phase during solidification. The phase has an excellent performance in superconductivity [1-3]. McAlister and Murray [4] collected a lot of research results at an earlier stage. Based on these information, Srikanth et al. [5] observed the metastable phase diagram. Recently, Al-Ge alloy can obtain deep undercooling with an electromagnetic oscillating drop method [6,7], so more and more investigations have been performed on the metastable phase at a deep undercooling state.The liquid structure of Al-Ge alloy has also been investigated. The electronic density of states of this alloy has been measured by Gamppet et al. [8] both in the liquid and in the amorphous state. A decrease of density of states at the Fermi level has been measured for the amorphous state, a small one in the liquid state, vanishing with temperature. This feature has been explained as being induced by the atomic structure. Grosdidier and Gasser [9] obtained the structure factors by neutron scattering on liquid Al-Ge alloys. A characteristic peak was found on every curve of the structure factor. The peak decreased from aluminum-rich alloys to germanium-rich alloys. They pointed out that the particular shape of the alloy structure factor was mainly due to the germanium-germanium interaction.To sum up the above arguments, the investigations are a series of studies intended to focus on the fields of metastable phase and particularity of liquid structure. However, our understanding of liquid structures, including the structure correlation between liquid and solid states, is relatively imperfect although the investigations on the liquid structure have been carried out for a long time. It is still an important and unsolved problem in condensed state physics. In addition, the reason of undercooling state about Al-Ge alloy during solidification is hardly reported. So it is necessary to explore the cause of undercooling from the point of the structure correlation between liquid and solid states.In this paper, the scattering intensities of liquid Al 71.6 Ge 28.4 alloy were investigated by means of X-ray diffraction from the temperature above liqu...

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Gallium antimonide (GaSb) structure

Landolt-Börnstein - Group III Condensed Matter

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Pressure-induced amorphous phases

Cited by 50 publications

References 4 publications

Pressure-induced amorphization and an amorphous–amorphous transition in densified porous silicon

Pressure-induced amorphization and an amorphous–amorphous transition in densified porous silicon

Structure correlation of Al71.6Ge28.4 eutectic alloy between liquid and solid states

Gallium antimonide (GaSb) structure

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