Physical behavior of germanium under shock wave compression

Graham, R. A.; Jones, O. E.; Holland, J. R.

doi:10.1016/0022-3697(66)90147-8

Cited by 38 publications

(3 citation statements)

References 24 publications

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“…Alternatively, it has been shown that application of pressure leads to amorphization of materials whose melting point displays a negative Clapeyron slope (dT/dP < 0) (5-9); germanium (Ge) falls into this category (10). However, instead of pressure-induced amorphization, numerous studies, under both static (11,12) and dynamic conditions (13)(14)(15), have shown that Ge undergoes a polymorphic transition at elevated pressures. Consequently, amorphization was not unambiguously identified in Ge until Clarke et al (16) observed the indentation-induced crystalline-to-amorphous transition.…”

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confidence: 99%

Generating gradient germanium nanostructures by shock-induced amorphization and crystallization

Zhao

Kad

Wehrenberg

et al. 2017

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

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Gradient nanostructures are attracting considerable interest due to their potential to obtain superior structural and functional properties of materials. Applying powerful laser-driven shocks (stresses of up to one-third million atmospheres, or 33 gigapascals) to germanium, we report here a complex gradient nanostructure consisting of, near the surface, nanocrystals with high density of nanotwins. Beyond there, the structure exhibits arrays of amorphous bands which are preceded by planar defects such as stacking faults generated by partial dislocations. At a lower shock stress, the surface region of the recovered target is completely amorphous. We propose that germanium undergoes amorphization above a threshold stress and that the deformation-generated heat leads to nanocrystallization. These experiments are corroborated by molecular dynamics simulations which show that supersonic partial dislocation bursts play a role in triggering the crystalline-to-amorphous transition.amorphization | laser shock | nanocrystallization | germanium | gradient materials A morphous and gradient nanostructures are drawing intense attention due to their superior functional and mechanical properties (1, 2). Since they are thermodynamically metastable, amorphous materials can transform into nanocrystalline ones if appropriate treatments are applied (3). One of the most common methods to achieve amorphization is to quench a liquid at ultrafast cooling rates, which is extremely difficult for most pure elements (4). Alternatively, it has been shown that application of pressure leads to amorphization of materials whose melting point displays a negative Clapeyron slope (dT/dP < 0) (5-9); germanium (Ge) falls into this category (10). However, instead of pressure-induced amorphization, numerous studies, under both static (11, 12) and dynamic conditions (13-15), have shown that Ge undergoes a polymorphic transition at elevated pressures. Consequently, amorphization was not unambiguously identified in Ge until Clarke et al. (16) observed the indentation-induced crystalline-to-amorphous transition. More recently, a high-speed nanodroplet test also showed surface amorphization of Ge in an extremely localized manner (17).Despite being widely studied, the underlying microstructural mechanisms of pressure-induced amorphization remain vague. This is due to the notorious brittleness of germanium at room temperature which renders its recovery from pressurization extremely challenging. The deposition of high-power pulsed-laser energy onto a millimeter-scale target generates transient states of extreme stresses that promptly build up and decay rapidly as the pulse propagates. The short duration of the stress pulse and impedancematched encapsulation preserves the integrity of the target by suppressing the full development of cracks and enables postshock microstructure characterization. Using this methodology, we have previously reported shock-induced amorphization in silicon (18) and boron carbide (19). Before that, Jeanloz et al. (20) discovered this ...

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confidence: 99%

Generating gradient germanium nanostructures by shock-induced amorphization and crystallization

Zhao

Kad

Wehrenberg

et al. 2017

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

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“…Ge was chosen as the crystal of study as it exhibits a complex multi-wave response following dynamic loading, which would display clear signatures in both imaging and diffraction. [14][15][16] We achieve the simultaneous imaging and diffraction by using a)…”

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“…We observe, consistent with previous studies, a strong elastic response, beginning at 27 ns, reaching a peak velocity of $0.5 km/s, corresponding to a Hugoniot Elastic Limit (HEL) of 5 GPa. [14][15][16] Following the strong elastic wave, a second wave emerges, and the material is compressed up to a peakpressure state of 12 GPa.…”

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confidence: 99%

Simultaneous 8.2 keV phase-contrast imaging and 24.6 keV X-ray diffraction from shock-compressed matter at the LCLS

Seiboth

Fletcher

McGonegle

et al. 2018

Applied Physics Letters

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Equation of state under high pressure for metallic Si and Ge

Soma

1979

Physica Status Solidi (b)

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Equation of State under High P r e s s u r e for Metallic Si and Ge Akita University PP B Y T. SOMARecently studies of physical properties under high p r e s s u r e became m o r e interesting because of the development of the measuring technique. It has been wellknown as the typical pattern of the covalent-metallic phase transition that Si and Ge were transformed to the metallic phase with f3-Sn-type structure exceeding 100 kbar (for example, see Minomura and Drickamer /l/). Then, when, after the phase transition, the p r e s s w e was removed, new phases such as complicated b.c.c. /2/ and hexagonal /3/ for Si and tetragonal /4/ for Ce were produced. However, few detailed studies under higher p r e s s u r e after the phase transition have been done (f. i. see Bundy /5/ and Pavlovskii /6/). Previously, we /7/ reported the equation of state under p r e s s u r e for Si andCe with the diamond-type structure. In the background of our work, we / 8 / have applied the self-consistent local Heine-Abarenkov model potential and the perturbational treatment in the Jones zone scheme by Heine-Jones, and obtained the calculated cohesive energy, bulk modulus, and phonon dispersion curves for Si, Ce, and a-Sn in good agreement with the experimental data. In the PfkborJ-P ( h W -t7g.l ry.2

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Physical behavior of germanium under shock wave compression

Cited by 38 publications

References 24 publications

Generating gradient germanium nanostructures by shock-induced amorphization and crystallization

Generating gradient germanium nanostructures by shock-induced amorphization and crystallization

Simultaneous 8.2 keV phase-contrast imaging and 24.6 keV X-ray diffraction from shock-compressed matter at the LCLS

Equation of state under high pressure for metallic Si and Ge

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