The structure of gold alloys in the liquid state

Rivlin, V. G.; Waghorne, R.M.; Williams, Geoffrey T.

doi:10.1007/bf03215410

Cited by 7 publications

(16 citation statements)

References 23 publications

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“…This lower kinetic barrier can be understood in terms of the liquid structure. As reported by Rivlin et al, 15 XRD studies of liquid Au−Ge show that the liquid structure resembles close-packing in the composition range between pure Au and the eutectic composition; i.e., it is much closer in atomic coordination and density to the metastable β alloy phase than it is to the two-phase equilibrium crystal system which includes the relatively open structure of diamond cubic Ge. Takeda et al 16 support Rivlin's findings of a close-packed liquid and further show that the Ge atoms substitute randomly for Au atoms in the nearest neighbor and second neighbor configurations.…”

Section: ■ Results and Discussionmentioning

confidence: 71%

“…However, when we rapidly quenched the liquid droplets in the Aduro holder, we were able to form the hcp metastable Au−Ge alloy structure, the β phase, that has previously been reported in conventional splat-cooling experiments performed on bulk-like Au−Ge liquid droplets. 15,17,18 The metastable β phase is reported to have a composition range of 17−25 atom % Ge, and to have lattice parameters similar to those expected for hcp Au (within 1%). 25 Figure 1 shows a nanoparticle quenched from the melted state to room temperature in the Aduro holder by setting the heating bias to zero from a starting state of 370°C.…”

Section: ■ Results and Discussionmentioning

confidence: 91%

“…These include the use of gold alloys as solders in the semiconductor industry; 13,14 studies of the metal−semiconductor liquid structure 15,16 and of metastable structures achieved by rapid quenching of the liquid, 15,17,18 and the growth of semiconductor nanowires. 19 We have previously reported the discovery of metastable hexagonal close-packed (hcp) Au nanoparticles that form following Ge nanowire growth when the Au−Ge liquid catalyst droplet crystallizes.…”

Section: ■ Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Crystallization Pathway for Metastable Hexagonal Close-Packed Gold in Germanium Nanowire Catalysts

Marshall

Thombare

McIntyre

2015

Crystal Growth & Design

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The recent discovery of hexagonal-close-packed (hcp) Au nanoparticles, crystallized at the tips of Ge nanowires following vapor−liquid−solid (VLS) growth, prompts interest in the mechanism of metastable phase formation in the Au catalyst. The equilibrium structure of Au is face-centered cubic, and observation of hexagonal close-packing in Au is very rare.Here we report on eutectic melting of Au nanocatalysts in the transmission electron microscope (TEM), followed by rapid quenching, and subsequent in situ annealing at intermediate temperatures. A metastable hexagonal Au−Ge alloy phase solidifies during quenching of the Au−Ge liquid in the TEM, and it is a likely precursor to formation of metastable hcp Au during nanowire post-VLS cooling. A novel aspect of the hcp Au phase formation is the rejection of quenched-in Ge from the alloy during low-temperature in situ TEM annealing, while maintaining the metastable hcp crystal structure, indicating that this is the likely pathway for hcp formation following nanowire growth. The kinetics of metastable phase formation are discussed in relation to the unique characteristics of VLS nanowire growth: Ge supersaturation during growth and undercooling of the nanoscale liquid catalyst prior to crystallization at the end of growth.

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Section: ■ Results and Discussionmentioning

confidence: 71%

Section: ■ Results and Discussionmentioning

confidence: 91%

Section: ■ Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Crystallization Pathway for Metastable Hexagonal Close-Packed Gold in Germanium Nanowire Catalysts

Marshall

Thombare

McIntyre

2015

Crystal Growth & Design

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“…Slow reduction of power was used to minimise stress cracking as the core material solidified. Although the metal component might be expected to shrink and ameliorate the expansion of the silicon upon cooling, in eutectic systems the attractive interaction in the liquid phase leads to expansion of several percent upon solidification 56 .…”

Section: Methodsmentioning

confidence: 99%

Localised structuring of metal-semiconductor cores in silica clad fibres using laser-driven thermal gradients

et al. 2022

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The molten core drawing method allows scalable fabrication of novel core fibres with kilometre lengths. With metal and semiconducting components combined in a glass-clad fibre, CO2 laser irradiation was used to write localised structures in the core materials. Thermal gradients in axial and transverse directions allowed the controlled introduction, segregation and chemical reaction of metal components within an initially pure silicon core, and restructuring of heterogeneous material. Gold and tin longitudinal electrode fabrication, segregation of GaSb and Si into parallel layers, and Al doping of a GaSb core were demonstrated. Gold was introduced into Si fibres to purify the core or weld an exposed fibre core to a Si wafer. Ga and Sb introduced from opposite ends of a silicon fibre reacted to form III-V GaSb within the Group IV Si host, as confirmed by structural and chemical analysis and room temperature photoluminescence.

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“…Although the metal component would be expected to shrink and ameliorate the expansion of the silicon on cooling, in eutectic systems, the attractive interaction in the liquid phase leads to expansion of several percent upon solidificatio. 37…”

Section: Traveling Melt Zone Recrystallizationmentioning

confidence: 99%

Thermal structuring of metal-semiconductor core fibres: toward optoelectronic device fabrication

Song

Laurell

Meehan

et al. 2021

Preprint

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Combining metal and semiconducting components in the core of a glass-clad fibre brings new breadth to the range of structures that can be fabricated using localized thermal gradients. Both axial and lateral structuring of fibres drawn withm ultiple components is demonstrated, as well as the introduction, segregation and chemical reaction of metal components within an initially pure silicon core. Gold and tin longitudinal electrodes fabrication, segregation of GaSb and Si in an initially inhomogeneous fiber into parallel axial layers and Al doping of a GaSb core were demonstrated. Gold was introduced into Si fibers to purify the core or weld an exposed core to a Si wafer. Ga and Sb introduced from opposite ends of a silicon fibre reacted to form III-V GaSb within the Group IV Si host, as confirmed by structural and chemical analysis and room temperature photoluminescence.

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The structure of gold alloys in the liquid state

Cited by 7 publications

References 23 publications

Crystallization Pathway for Metastable Hexagonal Close-Packed Gold in Germanium Nanowire Catalysts

Crystallization Pathway for Metastable Hexagonal Close-Packed Gold in Germanium Nanowire Catalysts

Localised structuring of metal-semiconductor cores in silica clad fibres using laser-driven thermal gradients

Thermal structuring of metal-semiconductor core fibres: toward optoelectronic device fabrication

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