Le Système Gazeux Gallium–Chlore: Etude par Spectrométrie Raman. 2–Analyse Quantitative

Abstract

Procedures for the quantitative treatment of Raman spectra are proposed for the investigation of gallium+hlorine gaseous mixtures. They are based on correlations between pressures and Raman band intensities and require a knowledge of reliable entropy and heat capacity data for the main gaseous species. For the ratio CI/Ga = 3 and between 590 and 690 K, the pressure determinations from the band intensity evolution corresponding to the symmetric vibrational modes 'ul' of Ga,CI, and GaC13 confirm the starting consideration of the single equilibrium Ga,C16(g) 2GaCl,(g). They lead to an enthalpy of dissociation of Ga,C16 very close to the literature data. For CI/Ga< 3 and between 800 and 950 K, the treatment of the Raman spectra is performed by computation of the GaCl spectrum in order to discriminate between the GaCI, 'vl' band intensity and the GaCl 'us' branch intensity. This intensity difference and the GaCl 'uQ' branch intensity are used for pressure determinations. The results are consistent with the proposed equilibrium 2Ga(l) + GaC13(g) S 3GaCl(g). They lead to a calculated reaction enthalpy that allow one to select a reliable value for the enthalpy of formation of GaCI.

Gallium Trichloride Fluid: Dimer Dissociation Mechanism, Local Structure, and Atomic Dynamics

“…The Cl-Cl bonds are associated with molecular chlorine formed in the supercritical fluid resulting from the monomer disproportionation: GaCl 3 ⇌ GaCl + Cl 2 . Gallium monochloride is typically observed at high temperatures, becoming predominant above 1100 K [ 17 , 18 ]. In our case, GaCl remains elusive, either forming intermediate species via homopolar Ga-Ga and heteropolar Ga-Cl bonding or persisting as diatomic molecules (with a residual 50% occurrence in the latter two cases).…”