Application of scaled nucleation theory to metallic vapor condensation

Abstract

In this paper we report that scaled nucleation theory (SNT) can describe moderately well the observed nucleation behavior of a significant number of refractory materials if a more appropriate value of a quantity commonly referred to as the excess surface entropy is used. With the availability of more reliable critical point and liquid property data, we are better able to calculate this quantity and we find that for refractory materials it can be as small as one half to one third the quantity traditionally used in its approximation. As a result of using more accurate values, we find considerably better agreement between SNT and experiment than what was originally determined. We also explain why using surface tension slope information to determine the excess surface entropy can lead to substantial errors in the SNT supersaturation prediction.

Scaling of the Nucleation Rate and a Monte Carlo Discrete Sum Approach to Water Cluster Free Energies of Formation

“…17 Surprisingly, this scaling law agreed with data for a range of materials far better than would be justified by the form for J o,class . 19,[23][24][25][26] In fact, the toluene and nonane data over a range of nucleation rates above onset appeared to agree well with a simple scaled model, J scaled…”

Dust formation in winds of long-period variables

“…There was some hope that scaled nucleation theory (Hale 1986) might be a better way to describe the condensation of refractory vapors. The scaled nucleation theory is a generalization of classical nucleation theory by scaling the relevant parameters to those of the vapor at the critical temperature and pressure and the agreement with experimental data for various molecular fluids was rather good (Martinez et al 2001). As a result of this success scaled nucleation theory was subsequently applied to selected refractory nucleation data (Hale et al 1989) with some success.…”

Vapor Phase Homogeneous Nucleation of Higher Alkanes: Dodecane, Hexadecane, and Octadecane. 2. Corresponding States and Scaling Law Analysis

“…7,8,14 This scaled model has proven to be a powerful tool for correlating nucleation threshold behavior for diverse substances ranging from simple molecules 7,8 and nonpolar 9,19,20 and highly polar molecules 13,[21][22][23] to metallic vapors and vapors of refractory materials. [10][11][12] For a nucleation rate of 1 cm -3 s -1 , the scaling law is expressed as 14 where Ω is the excess surface entropy per molecule in the cluster. The corresponding bulk liquid value of Ω can be approximated by the Eötvös constant, 30,31 K e , which is defined as where M is the molecular weight, F is the liquid density, σ is the surface tension, and N A is Avogadro's number.…”

“…2 Scaled models for homogeneous nucleation provide useful ways of correlating the experimental data for a series of different materials with their molecular properties. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] In particular, scaling models deal with the correlation of critical supersaturations (S c (T)), supersaturations required for the onset of nucleation at a rate of 1 drop/cm 3 /s) and nucleation rates, J(S,T), of wide classes of substances over wide ranges of experimental conditions using reduced (nondimensional) thermodynamic parameters. These correlations lead to identifying universal temperature dependencies, which complicate the extraction of general patterns from the nucleation data of individual substances.…”

“…These correlations lead to identifying universal temperature dependencies, which complicate the extraction of general patterns from the nucleation data of individual substances. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Systematic studies of homogeneous nucleation of different classes of compounds with a variety of molecular properties are desirable in order to test nucleation theories. Such studies provide insight into the role of different molecular properties in the nucleation process.…”