Specific features of mass and heat transfer in microparticles and nanoparticles formed upon electrocrystallization of copper

Викарчук, А. А.; Yasnikov, I. S.

doi:10.1134/s1063783406030267

Cited by 7 publications

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“…Reports are available [30][31][32][33] in which the emergence of quasicrystals with pentagonal symmetry and variety of structural types (amorphous or perfect crystalline) in an electrodeposited metal are explained by the metal's attaining of a high-temperature "liquid phase" state and subsequently cooling down during its electrodeposition. For example, some papers [30][31][32] on phase formation in electrodeposited copper show that "... the temperature in the growing islet, if its size is within a certain range, rises abruptly due to peculiarities of heat exchange in electrocrystallization (and can thus exceed copper melting point) and then drops down to the substrate temperature..." [32]. Assuming that a metals being electrodeposited from water solutions indeed solidifies from a molten state due to some growing islets reaching the metal's melting point, one should contemplate islet growth stoppage at above 100 °C because of a film of vapour which will emerge around the islet surface.…”

Section: Resultsmentioning

confidence: 99%

“…Furthermore, if metals pass a high-temperature liquid state stage during electrodeposition, they will, during solidification in the absence of a high supercooling, assume dendritic, rather than spherulitic forms and produce no pentagonal quasicrystals. In this context, the mechanism of phase formation in metals being electrodeposited as suggested in [30][31][32][33] appears unlikely.…”

Section: Resultsmentioning

confidence: 99%

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Structural Features of Electrodeposited Metals as a Result of Ultra-Rapid Solidification of a Highly Supercooled Liquid Metal Phase

Girin¹

2015

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With a view to validating the existence of the phenomenon of phase formation via a liquid state stage in metals being electrodeposited, experiments were carried out to reveal electrodeposited metal's structural features typical of metals produced by solidification at ultra-high rates under high supercooling, and to establish consistent changes in metal structural characteristics with increasing degree of supercooling in electrodeposition. Following experimental facts in favour of the existence of the phenomenon in point were found: (1) occurrence of spherulites and pentagonal quasicrystals in electrodeposit layers adjoining the cathode, the occurrence being typical of metals produced by ultra-rapid solidification of a highly supercooled liquid metal phase; (2) emergence of the electrodeposited metals solely in a spherulitic form when transition of spherulitic growth to drusy growth with increasing deposit thickness was prevented; and (3) regular change in characteristics of point, linear and planar defects in the crystalline lattice with increasing degree of supercooling in electrodeposition of metals.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Structural Features of Electrodeposited Metals as a Result of Ultra-Rapid Solidification of a Highly Supercooled Liquid Metal Phase

Girin¹

2015

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“…Ранее, в процессе анализа экспериментальных данных по электроосаждению меди, в работе [1] была предложена модель, которая основывалась на предположении, что строение, размеры и форма ГЦК-кристаллов определяются особенностью процессов массо-и теплообмена, протекающими в островках роста, образующихся на начальных стадиях электрокристаллизации металлов. Данная модель впоследствии получила три независимых экспериментальных подтверждения [2][3][4].…”

Section: Introductionunclassified

“…Данная модель впоследствии получила три независимых экспериментальных подтверждения [2][3][4]. На основе предложенной модели варьированием условий электроосаждения и типом подложки были реализованы сценарии превращения островков роста меди в кристаллы и кристаллические образования различного габитуса и внутреннего строения [1], в том числе и в кристаллы с пентагональной симметрией. Многообразие форм роста и особенности строения пентагональных микрокристаллов меди были отражены в монографии [5].…”

Section: Introductionunclassified

Microcrystals with pentagonal symmetry formed during electrodeposition of silver

Yasnikov¹

2011

LoM

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В работе обсуждаются морфологические особенности строения микрокристаллов серебра с пентагональной симметрией, формирующихся в процессе электроосаждения при варьировании технологических параметров (плотность тока, перенапряжение на катоде, время осаждения) и приводятся соответствующие экспериментальные данные. Ключевые слова: электроосаждение, серебро, пентагональная симметрия, дефект дисклинационного типа. The morphology of silver single crystals with pentagonal symmetry obtained by electrodeposition with varying parameters such as the current density, cathode overvoltage, and deposition time is discussed and respective experimental data are presented.

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“…As was shown theoretically [6] and experimentally [7][8][9], the structure, the size, and the scenario of the development of crystalline aggregates depend on the heat and mass transfer processes that occur in the growth islands having formed at the early stages of metal electrocrystallization. In this case, the final habit of a small particle with pentagonal symmetry is Abstract-A technique is proposed for producing nanostructured materials saturated with twin boundaries by compacting (pressing) small pentagonal electrolytic particles.…”

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confidence: 97%

Production of materials saturated with twin boundaries by compacting electrolytic microparticles

Yasnikov

Denisova

2012

Tech. Phys.

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The creation of new materials with unusual proper ties, which are determined by the "technology (tech nique) structure properties" chain, is one of the challenging problems in physics and engineering. In particular, compacting (pressing) small metallic particles is one of the methods for producing new functional and nanostructured materials [1]. The choice of the structure of small metallic particles for the subsequent production of a compound determines its structure and, hence, properties.From this standpoint, a twin boundary is of partic ular interest as a planar lattice defect and a structural element of a small particle, since it can impart unique properties to a micro object. For example, a high con centration of twin boundaries in electrodeposited metals increases their thermal stability and micro hardness and decreases their plasticity [2]. When a metal exhibiting a superconducting transition has a twin boundary, specific conditions for Cooper pairing, which are favorable near a twin boundary as compared to the volume, can appear near this boundary [3]. Cor respondingly, the superconducting transition temper ature in the twinning plane can be higher than this temperature in the crystal structure around the twin boundary [3].Therefore, the purpose of this work is to propose a technique for producing nanostructured materials sat urated by twin boundaries using the compacting of small electrolytic particles as an example.As the microparticles forming the basis of a future compound, we chose small metallic copper electrode posited particles. A technique for the formation of small metallic copper particles with a given structure has been developed and tested [4]. Experimental investigations demonstrate that small particles with pentagonal symmetry are the main carrier of twin boundaries. According to the classification in [5], they have the following three basic habits: small decahedral particles (Fig. 1a), needle like particles (Fig. 1b), and small icosahedral particles (Fig. 1c).Particles of the first two types have one fivefold symmetry axis and five twin boundaries. The third type of particles, namely, small icosahedral particles, have six fivefold symmetry axes and 30 twin boundaries per particle [5]. Small icosahedral particles consist of 20 weakly distorted single crystal tetrahedral regions, and each tetrahedron is a close packed element of the fcc structure. Tetrahedra connect with each other along {111} boundaries, which transform into twin boundaries inside a small particle [5]. Obviously, these small icosahedral particles are the best candidates for compacting followed by the formation of a material saturated by twin boundaries.The choice of the electrodeposition parameters that results in predominant formation of small icosa hedral particles was a challenging problem, and we solved this problem using the trial and error method. As was shown theoretically [6] and experimentally [7][8][9], the structure, the size, and the scenario of the development of crystalline aggregates depend on the heat and m...

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Specific features of mass and heat transfer in microparticles and nanoparticles formed upon electrocrystallization of copper

Cited by 7 publications

References 0 publications

Structural Features of Electrodeposited Metals as a Result of Ultra-Rapid Solidification of a Highly Supercooled Liquid Metal Phase

Structural Features of Electrodeposited Metals as a Result of Ultra-Rapid Solidification of a Highly Supercooled Liquid Metal Phase

Microcrystals with pentagonal symmetry formed during electrodeposition of silver

Production of materials saturated with twin boundaries by compacting electrolytic microparticles

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