The Rate of Evaporation of Tantalum

Langmuir, David B.; Malter, L.

doi:10.1103/physrev.55.748

Cited by 24 publications

(3 citation statements)

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“…[27] The data presented for Ta evaporation in Figure 6 are from the measurements performed by Langmuir and Malter [30] at high temperatures and high vacuum conditions and below the melting point of Ta. At very low pressures, higher Ta evaporation rates than the theoretic rates are observed.…”

Section: Evaporation Rate Of Pure Metalsmentioning

confidence: 99%

Vacuum Evaporation of Pure Metals

Safarian

Engh

2012

Metall Mater Trans A

114

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Theories on the evaporation of pure substances are reviewed and applied to study vacuum evaporation of pure metals. It is shown that there is good agreement between different theories for weak evaporation, whereas there are differences under intensive evaporation conditions. For weak evaporation, the evaporation coefficient in Hertz-Knudsen equation is 1.66. Vapor velocity as a function of the pressure is calculated applying several theories. If a condensing surface is less than one collision length from the evaporating surface, the Hertz-Knudsen equation applies. For a case where the condensing surface is not close to the evaporating surface, a pressure criterion for intensive evaporation is introduced, called the effective vacuum pressure, p eff . It is a fraction of the vapor pressure of the pure metal. The vacuum evaporation rate should not be affected by pressure changes below p eff , so that in lower pressures below p eff , the evaporation flux is constant and equal to a fraction of the maximum evaporation flux given by Hertz-Knudsen equation as 0.844 _ n Max . Experimental data on the evaporation of liquid and solid metals are included.

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Section: Evaporation Rate Of Pure Metalsmentioning

confidence: 99%

Vacuum Evaporation of Pure Metals

Safarian

Engh

2012

Metall Mater Trans A

114

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“…This indicated that the silicon melted and evaporated before the Ta could melt. As the vapor pressure of Si ( P v (Si) = 4.07 × 10 6 atm at T = 1623 K [ 14 ]) is higher than that of Ta ( P v (Ta) = 6.66 × 10 −6 atm at T = 3269 K [ 15 ]) and has a much lower melting ( T m (Si) = 1687 K, T m (Ta) = 3293 K [ 5 ]) and boiling ( T b (Si) = 3538 K, T b (Ta) = 5731 K) point, Si was placed at the bottom of the graphite crucible and Ta on top prior to evaporation in the reported experiment ( Figure 5 a).…”

Section: Resultsmentioning

confidence: 99%

“…By the end of the melting phase, the homogeneous Ta-Si liquid will have filled the crucible. During the evaporation phase, the evaporation rates of Ta and Si in the Ta-Si liquid would be expected to be higher and lower, respectively, to some degree compared to pure Ta ( R exap (Ta) = 6.80 × 10 −5 g·cm −2 ·s −1 at T = 3269 K [ 15 ]) and Si ( R exap (Si) = 14.1 × 10 7 g·cm −2 ·s −1 at T = 1623 K [ 14 ]). However, it is still expected that the evaporation rate of Si would still be significantly higher than that of Ta and thus the Si concentration in the vapour would be much higher than that of Ta.…”

Section: Discussionmentioning

confidence: 99%

Synthesis, Characterization, and Mechanism of Formation of Janus-Like Nanoparticles of Tantalum Silicide-Silicon (TaSi2/Si)

et al. 2014

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Metal-semiconductor Janus-like nanoparticles with the composition tantalum silicide-silicon (TaSi2/Si) were synthesized for the first time by means of an evaporation method utilizing a high-power electron beam. The composition of the synthesized particles were characterized using high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), selective area electron diffraction (SAED), and energy dispersive X-ray fluorescence (EDX) analysis. The system is compared to previously synthesized core-shell type particles in order to show possible differences responsible for the Janus-like structure forming instead of a core-shell architecture. It is proposed that the production of Janus-like as opposed to core-shell or monophase particles occurs due to the ability of Ta and Si to form compounds and the relative content of Ta and Si atoms in the produced vapour. Based on the results, a potential mechanism of formation for the TaSi2/Si nanoparticles is discussed.

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Getters and Getter Processes

Knoll

1959

Materials and Processes of Electron Devices

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The Rate of Evaporation of Tantalum

Cited by 24 publications

References 1 publication

Vacuum Evaporation of Pure Metals

Vacuum Evaporation of Pure Metals

Synthesis, Characterization, and Mechanism of Formation of Janus-Like Nanoparticles of Tantalum Silicide-Silicon (TaSi2/Si)

Getters and Getter Processes

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