High-pressure phases of group-IV, III–V, and II–VI compounds

Mújica, A.; Rubio, Ángel; Múñoz, A.; Needs, R. J.

doi:10.1103/revmodphys.75.863

Cited by 964 publications

(759 citation statements)

References 318 publications

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“…Our observation is different from that found in high-pressure experiments on c-Si, [36][37][38] where Si-I transforms to Si-II, or to many other crystalline forms, rather than to amorphous phase under high hydrostatic pressure. The absence of a-Si there indicates that plastic deformation is a more effective route to CAT in Si.…”

Section: Discussioncontrasting

confidence: 56%

In situ TEM study of deformation-induced crystalline-to-amorphous transition in silicon

et al. 2016

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The mechanism responsible for deformation-induced crystalline-to-amorphous transition (CAT) in silicon is still under considerable debate, owing to the absence of direct experimental evidence. Here we have devised a novel core/shell configuration to impose confinement on the sample to circumvent early cracking during uniaxial compression of submicron-sized Si pillars. This has enabled large plastic deformation and in situ monitoring of the CAT process inside a transmission electron microscope. We demonstrate that diamond cubic Si transforms into amorphous silicon through slip-mediated generation and storage of stacking faults (SFs), without involving any intermediate crystalline phases. By employing density functional theory simulations, we find that energetically unfavorable single-layer SFs create very strong antibonding interactions, which trigger the subsequent structural rearrangements. Our findings thus resolve the interrelationship between plastic deformation and amorphization in silicon, and shed light on the mechanism underlying deformation-induced CAT in general.

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Section: Discussioncontrasting

confidence: 56%

In situ TEM study of deformation-induced crystalline-to-amorphous transition in silicon

et al. 2016

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“…The R 3m, diamond, and Imma structures have fourfold coordination. The diamond structure is well known as occurring in carbon and also in silicon and germanium, while the Imma structure occurs in silicon and germanium [24]. We calculated the P4 1 32 sixfold coordinated structure proposed by Ma et al [9] to be roughly 100 meV per atom higher in enthalpy than our P4 2 =mbc structure over the range 200-600 GPa, and it is never the most stable structure.…”

Section: Prl 102 146401 (2009) P H Y S I C a L R E V I E W L E T T Ementioning

confidence: 99%

Dense Low-Coordination Phases of Lithium

Pickard

Needs²

2009

Phys. Rev. Lett.

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107

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Ab initio density-functional-theory calculations and a structure-searching technique are used to identify candidate high-pressure phases of lithium (Li). We predict threefold coordinated structures to be stable in the pressure range 40-450 GPa and fourfold structures at higher pressures. We describe these lowcoordination phases as elemental electrides. All of the stable phases are metallic but the Cmca-24 structure, and two distortions of it which are marginally the most stable in the pressure range 86-106 GPa, are nearly semiconducting with densities of electronic states at the Fermi energy of only a few percent of the free-electron value. DOI: 10.1103/PhysRevLett.102.146401 PACS numbers: 71.15.Nc, 61.66.Àf, 62.50.Àp In the close-packed structures adopted by Li at low pressures [1] the 2s electrons combine to form a half-filled nearly-free-electron band, consistent with the picture of a simple alkali metal. However, strong deviations from the canonical picture develop at higher pressures. Overlap of the Li 1s core electrons on neighboring atoms under strong compression has a profound effect upon the structures, which adopt lower coordination structures [2,3].The close-packed face-centered-cubic (fcc) phase of Li transforms to a structure of I 43d space group symmetry [4] at $40 GPa, via an intermediate phase of R 3m symmetry [3]. The R 3m phase has a distorted fcc structure, but the I 43d structure departs very substantially from close packing. I 43d has three short interatomic distances giving threefold coordination. Calculations show that the valence electronic density of states (e-DOS) dips around the Fermi energy (E F ) [3]. These features are consistent with the picture that reduced coordination numbers at high pressures arise from a Jahn-Teller-like distortion [2]. Calculations of the high-pressure phases also show an accumulation of electronic charge density within the interstitial region as the 2s electron density is pushed away from the atomic cores by Coulomb repulsion, Pauli exclusion, and the orthogonality of core and valence orbitals [2,3,5].Experiments suggest another phase transition at 60-70 GPa, although the new structure has not been determined [6,7]. A number of theoretical studies have sought to identify candidate phases at higher pressures [2,8,9]. A DFT study by Rousseau et al.[8] found a structure of Cmca symmetry to be more stable than I 43d above 88 GPa. This structure is named Cmca-24, appending the number of atoms in the conventional unit cell [8]. Cmca-24 consists of threefold coordinated atoms [8].Ma et al.[9] studied high-pressure phases of Li using a combination of ab initio DFT methods and an evolutionary search algorithm, finding a new structure of P4 1 32 symmetry which they calculated to be more stable than Cmca-24 above 300 GPa. This structure contains sixfold coordinated atoms. On the other hand, recent hightemperature DFT molecular dynamics simulations found fourfold coordinated Li atoms in the pressure range 150-810 GPa [10].Superconductivity has been observed in Li up...

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“…At each selected volume, the structures were fully relaxed to their equilibrium configuration through the calculation of the forces on atoms and the stress tensor. 26 In the relaxed equilibrium configuration, the forces are less than 0.004 eV/Å , and the deviation of the stress tensor from a diagonal hydrostatic form is less than 1-2 kbar.…”

Section: Ab Initio Calculationsmentioning

confidence: 99%

High-pressure optical and vibrational properties of CdGa2Se4: Order-disorder processes in adamantine compounds

Gomis

Vilaplana

Manjón

et al. 2012

Journal of Applied Physics

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High pressure structural stability of BaLiF3 J. Appl. Phys. 110, 123505 (2011) Pressure effects on the transitions between disordered phases in supercooled liquid silicon J. Chem. Phys. 135, 204508 (2011) Microfabrication of controlled-geometry samples for the laser-heated diamond-anvil cell using focused ion beam technology Rev. Sci. Instrum. 82, 115106 (2011) First-principles investigations of elastic stability and electronic structure of cubic platinum carbide under pressure J. Appl. Phys. 110, 103507 (2011) Additional information on J. Appl. Phys. High-pressure optical absorption and Raman scattering measurements have been performed in defect chalcopyrite (DC) CdGa 2 Se 4 up to 22 GPa during two pressure cycles to investigate the pressure-induced order-disorder phase transitions taking place in this ordered-vacancy compound. Our measurements reveal that on decreasing pressure from 22 GPa, the sample does not revert to the initial phase but likely to a disordered zinc blende (DZ) structure the direct bandgap and Raman-active modes of which have been measured during a second upstroke. Our measurements have been complemented with electronic structure and lattice dynamical ab initio calculations. Lattice dynamical calculations have helped us to discuss and assign the symmetries of the Raman modes of the DC phase. Additionally, our electronic band structure calculations have helped us in discussing the order-disorder effects taking place above 6-8 GPa during the first upstroke.

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High-pressure phases of group-IV, III–V, and II–VI compounds

Cited by 964 publications

References 318 publications

In situ TEM study of deformation-induced crystalline-to-amorphous transition in silicon

In situ TEM study of deformation-induced crystalline-to-amorphous transition in silicon

Dense Low-Coordination Phases of Lithium

High-pressure optical and vibrational properties of CdGa2Se4: Order-disorder processes in adamantine compounds

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