Thermodynamic properties of lanthanum and lanthanide halides: III. Thermodynamic functions of LnF2 (gas)

The molecular constants of LnF2 (Ln = La-Lu) have been estimated based on the available spectro-scopic characteristics of lanthanum and lanthanide difluorides. These constants have been used for calculating the reduced Gibbs energy −[G0(T) − H0(0)]/T of the compounds in the ideal gas state in the range 298.15–3000 K at the standard pressure p0 = 0.1 MPa. The electronic contribution to thermodynamic functions has been calculated taking into account the excitation energies of low-lying (<10 000 cm−1) electronic states of Ln2+ ions. The splitting of the ground state term of Ln2+ in the ligand field is estimated.