Controlled Growth of Oriented Systems of Whisker Crystals

Givargizov, E. I.; Kostyuk, Yu. G.

doi:10.1007/978-1-4684-1689-3_60

Cited by 3 publications

(8 citation statements)

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“…But with increasing thickness of the Ni coatings to about 3.75 and 5 m, the nucleation density decreased to about the same value of 10 9 /m 2 . In a similar case for the preparation of Si whiskers on Si(111) substrate catalyzed by Au particles from the hydrogen reduction of silicon tetrachloride, Givargizov and Kostyuk 15 reported that the nucleation density was found to be about 10 10 /m 2 . However, Sugiyama and co-workers 9 reported the growth of TiP whiskers catalyzed by Au particles exhibiting an opposite trend to that of ours.…”

Section: Resultsmentioning

confidence: 94%

Chemical Vapor Deposition of Silicon Carbide Whiskers Activated by Elemental Nickel

Leu

Hon

1999

J. Electrochem. Soc.

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Monolithic components based on metals, ceramics, and polymers are commonly reinforced by second-phase reinforcements with the aim of improving their mechanical properties. Silicon carbide (SiC) whiskers exhibiting high strength, high elastic modulus, low density, and high thermal and chemical stability have long been an attractive fibrous reinforcement for various composite materials. Historically SiC whiskers have been prepared by numerous approaches, among which the vapor-phase reaction of silanes 1 and the carbothermal reduction of silica-containing materials 2 are the two major routes for their preparation.The demonstration of the vapor-liquid-solid (VLS) mechanism for the growth of whiskers was proposed in the 1960s by Wanger and co-workers, 3-5 and many attempts have been conducted for the growth of such highly anisotropic crystals ever since. The main feature that differentiates this mechanism from others is the presence of a liquid-phase intermediate between the vapor feed and the solid whisker being grown. This liquid surface acted as an ideally rough surface and is a preferred site for the condensation of constituents of whiskers from the vapor phase. Moreover, the presence of a liquid medium favors the precipitation of crystalline material from the solid-liquid interface as the liquid phase is supersaturated with the constituents. Both issues mentioned above characterize the VLS mechanism as an efficient way for whisker growth. As cooled from the deposition temperature, the liquid solution in the usual form of a solidified spherical droplet at the tip of the whisker is commonly considered to be evidence for the operation of the VLS mechanism.Since the presence of a liquid solution is essential for the effective operation of the VLS mechanism, the characteristics of the liquid-forming agent (also called liquid-forming impurity or liquidforming catalyst) on the growth of whiskers have long been a subject of great interest to scientists and engineers. In fact, the subject had been discussed in varying degrees of depth as described in almost all published results on the deposition of whisker crystals. Wagner and Ellis 4 and Tamari and Kato 6 had extensively investigated the effect of various liquid-forming agents on the growth characteristics of the VLS-grown silicon (Si) and titanium carbide (TiC) whiskers, respectively. Knippenberg and Verspui 7 and Motojima et al. 8 had surveyed the catalytic effect of various liquid-forming agents on the deposition of SiC whiskers from the vapor-phase reaction. Sugiyama et al. 9 had investigated the dependence of the nucleation behavior of TiP whiskers on the characteristics of the Au catalyst drops. Tian et al. 10 had briefly claimed that too much catalyst added would cause whisker kinking and branching during the carbothermal reduction of silica for preparing SiC whiskers; however, powder product would mix with whiskers if too little agent was added. Though the importance of the presence of a liquid phase on the growth of whiskers has been fully recognized, yet the e...

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Section: Resultsmentioning

confidence: 94%

Chemical Vapor Deposition of Silicon Carbide Whiskers Activated by Elemental Nickel

Leu

Hon

1999

J. Electrochem. Soc.

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“…It is well-known that the formation of easy-melting-point eutectics needed for whiskers growth can be ensured by introducing some elements into the starting mixture . The additives of sodium tungstate and oxides of bivalent metals capable to form tungstates MWO 4 and eutectics MWO 4 + WO 3 have been used for preparation of the reaction mixes with NiWO 4 .…”

Section: Resultsmentioning

confidence: 99%

“…In the past few decades, there has been considerable research and technological interest in new commercially viable processes for the growth of whiskers of metals and their compounds and in the underlying growth mechanisms. − Particular attention has been paid to the preparation of single crystals no larger than 1 μm in cross-section size, as they possess the greatest perfection of structure and unique high mechanical strength, chemical stability, and unusual electrophysical characteristics. Some of the transition metals nanowires can find potential applications in gas sensors and as electron sources in electron microscopes.…”

Section: Introductionmentioning

confidence: 99%

“…Even though many studies were concerned with the growth of whiskers of various materials, processes for the preparation of hard-melting metal whiskers have been described in very few reports. There is limited information regarding the growth of tungsten whiskers, predominantly dendritic, through high-temperature halide vapor transport, and tungsten oxide whiskers in the presence of halides of other metals (Ni, Pt, Pd) in hydrogen atmosphere . The vapor−liquid−solid (VLS) method is very effective in preparing of nanoscale single crystals, but according to Givargizov it is rather difficult to use it for the growing of hard-melting metals whiskers because of the large difference between the formation temperatures of stable liquid phases and the decomposition temperatures of gaseous compounds of the metals.…”

Section: Introductionmentioning

confidence: 99%

“…There is limited information regarding the growth of tungsten whiskers, predominantly dendritic, through high-temperature halide vapor transport, and tungsten oxide whiskers in the presence of halides of other metals (Ni, Pt, Pd) in hydrogen atmosphere . The vapor−liquid−solid (VLS) method is very effective in preparing of nanoscale single crystals, but according to Givargizov it is rather difficult to use it for the growing of hard-melting metals whiskers because of the large difference between the formation temperatures of stable liquid phases and the decomposition temperatures of gaseous compounds of the metals. Recently, there are several reports about fabrication methods of tungsten nanowires with using chemical vapor deposition process and catalytic metal systems.…”

Section: Introductionmentioning

confidence: 99%

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Mechanism of the Single-Crystal Tungsten Whiskers Growth in the Process of the NiWO₄ Reduction by CO

et al. 2008

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Experimental evidence is presented that the growth of tungsten whiskers in the process of the NiWO 4 reduction by carbon oxide occurs in accordance with the vapor-liquid-solid mechanism. A liquid phase appears at 940 °C owing to the melting of the NiWO 4 -Na 2 WO 4 eutectic regions which are perhaps results of segregation of sodium impurities included in the reagents used. The presence of the liquid phase ensures for both Ni and W the comparable rates of allocation from the nickel tungstate crystal lattice leading to the formation of the R-W + NiW two-phase regions. The oriented growth of tungsten whiskers during the further reduction of the melt tungstate zones is associated with the W accumulation on the growth surfaces of the W single crystals in the two-phase regions. The result demonstrates that the reactivity of NiWO 4 increases with addition of CuO and Na 2 WO 4 which are capable to form easy-melting phases in the reactive system.

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Synthesis and Fabrication of Semiconductor Nanowires

Colinge¹,

Greer²

2016

Nanowire Transistors

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Controlled Growth of Oriented Systems of Whisker Crystals

Cited by 3 publications

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Chemical Vapor Deposition of Silicon Carbide Whiskers Activated by Elemental Nickel

Chemical Vapor Deposition of Silicon Carbide Whiskers Activated by Elemental Nickel

Mechanism of the Single-Crystal Tungsten Whiskers Growth in the Process of the NiWO₄ Reduction by CO

Synthesis and Fabrication of Semiconductor Nanowires

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Controlled Growth of Oriented Systems of Whisker Crystals

Cited by 3 publications

References 0 publications

Chemical Vapor Deposition of Silicon Carbide Whiskers Activated by Elemental Nickel

Chemical Vapor Deposition of Silicon Carbide Whiskers Activated by Elemental Nickel

Mechanism of the Single-Crystal Tungsten Whiskers Growth in the Process of the NiWO4 Reduction by CO

Synthesis and Fabrication of Semiconductor Nanowires

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Mechanism of the Single-Crystal Tungsten Whiskers Growth in the Process of the NiWO₄ Reduction by CO