Marc M. Faktor

Modified entrainment method for measuring vapour pressures and heterogeneous equilibrium constants. Part 2.—Equilibria in the water/gallium system

The modified entrainment method is applied to the study of a heterogeneous equilibrium: water vapour/liquid gallium, in the temperature range 1200–1400 K. Two gaseous gallium species, Ga2O and GaOH, were observed. The theory of the modified entrainment method is extended to this more complex case involving two simultaneous reactions.The entropies and enthalpies of formation are: [graphic omitted]

Modified entrainment method for measuring vapour pressures and heterogeneous equilibrium constants. Part 1.—Theory, and validation of the method using water and lead

A method of evaluating vapour pressures and equilibrium constants for heterogeneous reactions is proposed. It replaces the usually indeterminate contribution of gaseous transport in the conventional entrainment method by a calculable amount. The method was successfully applied at around room temperature to the evaporation of water, and to the vaporisation of lead in the temperature range 900–1050°C.

Growth of crystals from the gas phase. Part 4.—Growth of gallium arsenide by chemical vapour transport, and the influence of compositional convection

An experimental system for crystal growth by chemical vapour transport has been devised, so as to be compatible with the model used in a theoretical treatment described previously. The correlation between the experimental and theoretical growth rates is discussed and the influences of compositional convection and surface barriers to growth are considered.

Modified entrainment method for measuring vapour pressures and heterogeneous equilibrium constants. Part 4.—The gallium arsenide/hydrogen chloride system

The modified entrainment method described earlier has been used to study the GaAs/HCl system. Above about 900 K, the principal gallium vapour species is the monochloride, for which ΔH°f298=–63.2 ± 3 kJ mol–1 and S°298= 247 ± 2 J mol–1K–1. Below this temperature, another gallium species thought to be GaCl2 becomes important.

Thermodynamic study of the chemical vapour transport system GaAs–HBr using a modified entrainment method

Gallium arsenide is an important semiconducting compound in the manufacture of opto-electronic and microwave electronic devices. The chemical vapour transport system GaAs–HBr was studied using a modified entrainment method. Thermochemical data were obtained for the principal reactions, which were shown to result in the formation of GaBr and GaBr2 vapour molecules in the temperature range 700–1400 K. There is some evidence of the presence of other gallium species in the vapour.

Modified entrainment method for measuring vapour pressures and heterogeneous equilibrium constants. Part 3.—Measurement of diffusivity of hydrogen chloride in hydrogen and extension of the method to multicomponent diffusion at 700–1300 K

The binary diffusion coefficient of HCl in H2 may be represented by 0.54(T/273 K)1.85 cm2 S–1 over the temperature range 700–1300 K. We present a useful second-order approximation to multicomponent diffusion, which permits calculation of effective diffusion coefficients in multicomponent gas mixtures.