Thermodynamics of the lanthanide halides

The heat capacities of SmCl3, EuCl3, and GdCl3 have been measured from 5 to 350 K by adiabatic calorimetry. For SmCl3 and EuCl3, the calculated Schottky heat capacities may be compared with the difference in heat capacity between LaCl3 and the paramagnetic members, as before. For GdCl3 which lacks a Schottky contribution, the difference between the heat capacity of LaCl3 and GdCl3 may be discussed in terms of spectroscopic data on lattice vibration. Comparison between the measured entropies and the results of estimation schemes is presented. The values of (S0(298.15 K) - S0(0)) for SmCl3, EuCl3, and GdCl3 are 35.88, 34.43 and 36.19 calsub(th) K-1 mol-1, respectively. (author)