Revisiting the thermophysical properties of the a-type hexagonal lanthanide sesquioxides between temperatures of 5 K and 1000 K

Abstract Thermal measurements of the heat capacities and sensible enthalpies of the hexagonal (A-type) lanthanide sesquioxides of La, Ce, Pr, and Nd are reviewed and re-evaluated in terms of the lattice heat-capacity parameters and the Schottky levels obtained from lattice-sum calculations and analyses of the optical spectra. Re-examination of all the data typically from about T  =  5 K to 1000 K leads to revised values for the thermodynamic functions over this temperature range. Of particular interest, the values of Δ 0 298 S m o  /  R at T  =  298.15 K are given as 15.31, 17.88, 18.37, and 18.99 for La, Ce, Pr, and Nd hexagonal sesquioxides, respectively.