Structure of amorphous<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mtext>Ge</mml:mtext></mml:mrow><mml:mn>8</mml:mn></mml:msub><mml:msub><mml:mrow><mml:mtext>Sb</mml:mtext></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mrow><mml:mtext>Te</mml:mtext></mml:mrow><mml:mrow><mml:mn>11</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>:<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><

Akola, Jaakko; Jones, R.

doi:10.1103/physrevb.79.134118

Cited by 69 publications

(63 citation statements)

References 33 publications

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“…While at high density, the bonding of the In atoms is mostly octahedrallike, at low density a sizable fraction of tetrahedral-like geometries had been observed. This variability originates from a close competition between tetrahedral-like and octahedral-like sites, as previously found in related amorphous tellurides [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] . Nevertheless, this immediately suggests that in the presence of nanovoids in the amorphous/liquid phase, the inclusion of van der Waals interactions might be particularly important and may result is a somewhat higher density 46 .…”

Section: Application To Amorphous Insbmentioning

confidence: 65%

Inverse simulated annealing: Improvements and application to amorphous InSb

Los

Gabardi

Bernasconi

et al. 2016

Computational Materials Science

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An improved inverse simulated annealing method is presented to determine the structure of complex disordered systems from first principles in agreement with available experimental data or desired predetermined target properties. The effectiveness of this method is demonstrated by revisiting the structure of amorphous InSb. The resulting network is mostly tetrahedral and in excellent agreement with available experimental data.

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Section: Application To Amorphous Insbmentioning

confidence: 65%

Inverse simulated annealing: Improvements and application to amorphous InSb

Los

Gabardi

Bernasconi

et al. 2016

Computational Materials Science

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“…The frequency distribution of a-Te at 300 K shows two broad peaks reminiscent of the power spectra in Te-rich Ge/Sb/Te alloys. 31,77 The high-frequency …”

Section: Dynamicsmentioning

confidence: 99%

Structure and dynamics in amorphous tellurium and Tenclusters: A density functional study

Akola

Jones

2012

Phys. Rev. B

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Density functional/molecular dynamics simulations have been performed on amorphous tellurium (a meltquenched sample of 343 atoms at 300 K) and on Te clusters with up to 16 atoms. The former extend our calculations on liquid Te at 560, 625, 722, and 970 K [Phys. Rev. B 81, 094202 (2010)]. We discuss trends in structures (including those of other group-16 elements), electronic densities of states, and vibration frequencies. Chain structures are common in S and Se, but the chains in amorphous Te are short, and branching sites with threefold-coordinated atoms are common. The energy difference between two-and threefold local coordination depends sensitively on the exchange-correlation functional used. Cavities are characteristic of amorphous Te (37% of total volume), but are absent in crystalline (trigonal) Te.

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“…The size distribution of cavities (Fig. 5) shows periodic peaks at multiples of ∼ 35Å 3 , approximately the size of a single vacancy in the GST rock salt lattice with our definition of a cavity.…”

Section: Cavitiesmentioning

confidence: 99%

“…The rate limiting process in the write/erase cycle is the recrystallization of the amorphous bit, and demands for increasingly rapid transfer have focused much attention on this process. Two families of chalcogenide alloys dominate practical applications: (GeTe) 1−x (Sb 2 Te 3 ) x pseudobinary alloys [3], and doped alloys of Sb and Te near the eutectic composition Sb 70 Te 30 . The digital versatile disc (DVD)-RAM and Blu-ray Disc are examples of the first family, where Ge 2 Sb 2 Te 5 (GST, x = 1/3) is often taken as a prototype, and DVD-rewritable discs provide examples of the second [4].…”

Section: Introductionmentioning

confidence: 99%

Simulation of crystallization inGe2Sb2Te5: A memory effect in the canonical phase-change material

2014

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Crystallization of amorphous Ge 2 Sb 2 Te 5 (GST) has been studied using four extensive (460 atoms, up to 4 ns) density functional/molecular dynamics simulations at 600 K. This phase change material is a rare system where crystallization can be simulated without adjustable parameters over the physical time scale, and the results could provide insight into order-disorder processes in general. Crystallization is accompanied by an increase in the number of ABAB squares (A: Ge, Sb; B: Te), percolation, and the occurrence of low-frequency localized vibration modes. A sample with a history of order crystallizes completely in 1.2 ns, but ordering in others was less complete, even after 4 ns. The amorphous starting structures without memory display phases (>1 ns) with subcritical nuclei (10-50 atoms) ranging from nearly cubical blocks to stringlike configurations of ABAB squares and AB bonds extending across the cell. Percolation initiates the rapid phase of crystallization and is coupled to the directional p-type bonding in metastable GST. Cavities play a crucial role, and the final ordered structure is distorted rock salt with a face-centered cubic sublattice containing predominantly Te atoms. We comment on earlier models based on smaller and much shorter simulations.

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Structure of amorphousGe8Sb2Te11:<

Cited by 69 publications

References 33 publications

Inverse simulated annealing: Improvements and application to amorphous InSb

Inverse simulated annealing: Improvements and application to amorphous InSb

Structure and dynamics in amorphous tellurium and Tenclusters: A density functional study

Simulation of crystallization inGe2Sb2Te5: A memory effect in the canonical phase-change material

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