Mass Spectrometric Investigations of Thermodynamic Properties of the RbCl/GdCl₃ System

Abstract

The vaporization of pure RbCl, GdCl3, and RbCl‐GdCl3 samples of different phase compositions was investigated in the temperature range between 666 K and 982 K by use of the Knudsen effusion mass spectrometry. The gaseous species RbCl, Rb2Cl2, GdCl3, and RbGdCl4 were identified in the equilibrium vapours and their partial pressures were determined. The enthalpy of dissociation of RbGdCl4(g), ΔdissH°(859 K) = 263.1 ± 7.7 kJ mol—1, was evaluated by second law treatment of the equilibrium partial pressures. The thermodynamic activities of RbCl and GdCl3 were obtained at 800 K in the two‐phase fields {Rb3GdCl6(s) + liquid} and {RbGd2Cl7(s) + GdCl3(s)}. The Gibbs free energies of formation of the pseudo‐binary phases Rb3GdCl6(s), ΔfG°(800 K) = —75.1 ± 2.5 kJ mol—1 and RbGd2Cl7(s), ΔfG°(800 K) = —40.6 ± 1.2 kJ mol—1, were evaluated from the thermodynamic activities of the components. The results are compared with the available literature data.

The NaDyBr4 complex; its molecular structure and thermodynamic properties

“…The growing interest in the NaBr-DyBr 3 system is illustrated by recent studies of their Z. Varga · M. Hargittai ( ) Structural Chemistry Research Group of the Hungarian Academy of Sciences at Eötvös University, P.O.Box 32, H-1518, Budapest, Hungary e-mail: hargitta@chem.elte.hu mass spectra [5] and phase diagrams [6]. Mass spectrometry has proved to be the major experimental tool to study these systems [4,5,[7][8][9][10][11][12][13][14][15][16][17], yielding information about the composition and thermochemical properties of the systems found in the vapor. Modeling the processes in the high-temperature lamp facilitates improving lamp designs.…”