Size and temperature effects in wetting in island films

This paper is devoted to studies of wetting in metal island films on different substrates in the broad ranges of temperature (from 0.6 to 1.5 of the melting temperature), island size (from 3 nm to 10 mkm) and thickness of films serving as substrates (from 0 to 100 nm)

Effect of an electric field on coalescence in gallium island films

It was found that the external longitudinal electric field stimulates coalescence in gallium island films with different particle sizes on a poorly conducting carbon substrate, which can be considered as a manifestation of the particle mutual-charging effect. - - - - - - - - - - - - - - - Установлено, что внешнее продольное электрическое поле стимулирует процесс коалесценции в островковых пленках галлия с различным размером частиц на слабопроводящей углеродной подложке, что может рассматриваться как проявление эффекта взаимного заряжения частиц

Supercooling during metal crystallization under conditions close to weightlessness using island vacuum condensates

Островковые вакуумные конденсаты, свойства которых определяются поверхностными явлениями, а не силой тяжести, позволяют устранить эффект чужеродных примесей и собственных оксидов на переохлаждения ΔT в процессе кристаллизации. Их применение позволяет измерить зависимость ΔT от краевого угла смачивания между каплей жидкого металла и подложкой, на которой происходят конденсация и последующая кристаллизация. Для исследованных металлов (Au, In, Bi, Pb, Sn, Fe, Co, Ni) переохлаждение увеличивается с ростом краевого угла. Для углов смачивания больше 130° переохлаждение практически не зависит больше от материала подложки и приближается к значению несколько ниже 0,4 Ts, где Ts температура плавления массивного образца.Island vacuum condensates the properties of which are determined by surface phenomena rather than the force of gravity actually permit to eliminate the effect of alien impurities and own oxides on supercooling ΔT during crystallization. Their application also allows to measure the dependence of ΔT on the contact angle θ between a droplet of a liquid metal and the substrate on which condensation and subsequent crystallization occur. For the metals under study (Au, In, Bi, Pb, Sn, Fe, Co, Ni) the supercooling ΔT is shown to increase with the angle θ growing. With wetting angles θ > 130 ° the supercooling ΔT does not depend anymore on the substrate material and for θ → 180° it approaches a value somewhat below 0.4 Ts, where Ts is the bulk melting temperature

Effect of condensation conditions on phase formation in thin two-layer Ni/GaAs films

The temperature and structure state of substrate (NaCl poly- and single crystals) are shown to influence the structure of phases formed as a result of interaction between Ni and GaAs layers. In films on polycrystal substrates, polycrystal phases with structures similar to the γ-, γ'-, NiAs, Ni3Ga4 phases in Ni-Ga and Ni-As systems are formed besides the amorphous one. Single crystal substrate exerts an orienting influence resulting in the energetically favourable growth of the hexagonal phase of the triple system with parameters aγ''= aγ', cγ'' = 2cγ'. . . . . . . . . . . . . . . . . . . Показано, что температура и структурное состояние подложки (поли- и монокристаллов NaCl) оказывает влияние на структуру фаз, образующихся при взаимодействии слоев Ni и GaAs. На поликристаллических подложках в пленках, наряду с аморфной, образуются поликристаллические фазы, структура которых подобна фазам γ-, γ'-, NiAs, Ni3Ga4, в системах Ni-Ga, Ni-As. Монокристаллическая подложка оказывает ориентирующее действе и приводит к энергетически более выгодному росту гексагональной фазы тройной системы с параметрами aγ''= aγ', cγ'' = 2cγ'

Island size disrtibution under different substrate temperatures and film mass thickness

The technique of studying island size distribution versus different factors in films condensed via liquid phase has been developed. Distribution changes during growth of an island gallium film on amorphous carbon substrate have been examined. Temperature effects on microparticle size distribution in proximity of the maximum supercooling of tin condensates on carbon substrate have been investigated

Electronographic investigation of the temperature effect on the phase formation in thin double-layer Ni/GaAs films

The results of an electronographic investigation of the Ni—GaAs double-layer films phase composition depending on temperature at condensation of Ni at GaAs are presented. The structure and number of the phases being formed have been shown to depend both on ther-mal conditions at interaction of the Ni and GaAs layers and on the Ni to GaAs layer mass ratio: mNi//mGaAs = (0.5; 1.2)

Size Effect upon Solidification of Small Bismuth Particles

Electron microscopy was used to study the dependence of the crystallization temperature on the particle size upon solidification of small bismuth particles produced by vapor deposition on substrates of amorphous carbon. The crystallization temperature for particles 2–100 nm in diameter was found to decrease with decreasing diameter of the particles; and for particles 2–3 nm in diameter, supercooling was equal to zero. The results were analyzed within the classic theory of solidification; it was shown that, for the smallest particles, a size effect consisting in the change of the character of the liquid-crystal phase transition is observed

Size effects in wetting for highly dispersed systems

Wetting in systems with different dispersities of the solid and liquid phases and with different types of interfacial interaction was investigated. Studied were liq-uid metal-amorphous carbon and liquid metal-solid metal film-ionic crystal sys-tems in which the drop size and the thickness of film-substrates varied in the range 3x10^5–2x10^2 nm, respectively. It was found that for systems of the metal-amorphous carbon type a reduction in particle size and in thickness of carbon films brings about a size effect during wetting as a consequence of a decrease in the surface energy of the corresponding dispersed phase. For metal-metal-ionic crystal systems, a size effect during wetting is also observed but it is mainly caused by a changed nature of the interfacial interaction in the dispersed phases. Some parameters derived from the experimental data determine the dependence of the surface energy of small particles on their size

Lead wetting of thin nickel films deposited onto GaAs

The wetting of nickel films deposited onto (111) face of GaAs single crystals with island lead condensates has been studied. The wetting angle, θ, is found to depend on the Ni film thickness, t, and to change within the limits defined by wetting of pure GaAs (t = 0, θ ≈ 120°) and compact-state nickel wetting (t > 20 nm, θ ≈ 20°). The change of θ is explained as due to the surface heterogeneity arising as a result of chemical interaction between nickel film and gallium arsenide and of nickel dissolution in the liquid lead. - - - - - - - - - - - - - - - - Изучено смачивание островковыми конденсатами свинца пленок никеля, нанесенных на монокристалл арсенида галлия (грань (111)). Установлено, что краевой угол θ зависит от толщины t пленки Ni и изменяется в крайних пределах, соответствующих смачиванию чистого GaAs (t = 0, θ ≈ 120°) и смачиванию никеля в компактном состоянии (t > 20 nm, θ ≈ 20°). Изменение θ объясняется гетерогенностью смачиваемой поверхности, возникающей в результате химического взаимодействия пленки никеля с арсенидом галлия и растворения никеля в жидком свинце

Electronographic investigation of the temperature effect on the phase formation in thin double-layer Ni/GaAs films

The results of an electronographic investigation of the Ni—GaAs double-layer films phase composition depending on temperature at condensation of Ni at GaAs are presented. The structure and number of the phases being formed have been shown to depend both on ther-mal conditions at interaction of the Ni and GaAs layers and on the Ni to GaAs layer mass ratio: mNi//mGaAs = (0.5; 1.2)