The thermodynamic properties of 4 f metal trifluorides
Abstract
The experimental lowtemperature heat capacities of some solid 4 f metal trifluorides were used to reveal the trends in the behavior of variable parameters in the equation that described the lattice heat capacity component in the quasiharmonic approximation for the whole series of LnF_{3} (Ln = La, … Lu) compounds. The results were used to describe the temperature dependences of heat capacity over the temperature range from 0 K to the melting point T _{m}. The measured hightemperature enthalpy increments were used to determine corrections to the quasiharmonic description of heat capacities at T > ∼0.5 T _{m}. The reduced Gibbs energies were calculated over the temperature range 298.15 2000 K. The thermodynamic functions of LnF_{3} in the gaseous state were determined over the same temperature range in the rigid rotatorharmonic oscillator approximation. All calculations were performed taking into account excited electronic states whose energies did not exceed 10000 cm^{1}. The reliability of the thermodynamic functions obtained was proved by the convergence of the enthalpies of sublimation calculated by the second and third laws of thermodynamics from the experimental data on saturated vapor pressures. The complete set of the consistent thermodynamic properties of these compounds is described.
 Publication:

Russian Journal of Physical Chemistry A
 Pub Date:
 October 2007
 DOI:
 10.1134/S0036024407100019
 Bibcode:
 2007RJPCA..81.1543C