THERMOPHYSICAL PROPERTIES OF THE LANTHANIDE OXIDES. II. HEAT CAPACITIES, THERMODYNAMIC PROPERTIES, AND SOME ENERGY LEVELS OF SAMARIUM(III), GADOLINIUM(III), AND YTTERBIUM(III) OXIDES FROM 10 TO 350°K.¹

Abstract

Thermophysical Properties of Lanthanide Oxides 345 cal. (g.f.w. °K.)-1. Goldstein, et oZ.,4 5have estimated 36.92 cal. (g.f.w. °K.)-1 for this value by assuming the "spin-only" value (2R In 4) is achieved at 100°K. These authors based their estimate on their measured values of the entropy from 20 to 298.15°K. for lanthanum oxide of 30.28 cal .(g.f.w. °K.)-1 and for neodymium oxide of 33.12 cal. (g.f.w. °K.)~1. This investigation yielded 30.22 and 33.03, respectively, over the same range.Extension of thermal data on neodymium(III) oxide to lower temperatures together with magnetic susceptibility determinations at low temperatures are ob-

Heat capacity and entropy of monoclinic Gd2O3

“…Justice and Westrum [2] measured the heat capacity of this modification from T = (7 to 346) K, and Stewart et al [12] from T = (1.4 to 18) K, the results being in acceptable agreement in the overlapping temperature range. The low-temperature results for the cubic modifications also show an anomaly below 10 K, but it does not exhibit the lambda-type shape as was observed for monoclinic Gd 2 O 3 .…”

“…The interpretation of the systematics of the heat capacity and entropy of the lanthanide sesquioxide series presented in the preceding paragraph can be considered a refinement of the one presented earlier [7], which served as a basis for estimating the standard entropies of Pu 2 [7], that the lattice entropy in the actinide series is parallel to that in the lanthanide series, and can be scaled on the basis of the lattice entropy derived from the experimental value for Pu 2 O 3 [21], we obtain the values listed in table 3. The excess entropies for Am 2 O 3 and Cm 2 O 3 were simply calculated from S exs = Rln (g 0 ).…”

“…The low-temperature heat capacity of the lanthanide sesquioxides has been studied in great detail by Westrum and co-workers [1][2][3][4][5][6]. These authors reported measurements for twelve of the fifteen Ln 2 O 3 compounds, four having the triclinic A-type structure (La, Ce, Pr, and Nd), one the monoclinic B-type structure (Sm) and seven the C-type cubic structure (Gd, Er, Ho, Dy, Tm, Yb, and Lu).…”

“…The heat capacity of this 4f 7 compound does not contain an electronic component, except for the very low-temperature range (<20 K), and thus represents the lattice heat capacity (and entropy calorimetry from T = (5 to 400) K, of which the results will be reported here. Since the heat capacity of cubic Gd 2 O 3 has been measured by Justice and Westrum [2] a direct comparison of C lat for the monoclinic and cubic modifications is now possible.…”

Investigation on thermophysical properties of RE6UO12(s) (RE=La, Pr, Nd, Sm)

“…The accuracy in various energy levels can be verified from the measured and calculated Schottky heat capacity. This type of correlation of heat capacity with spectroscopy data is largely studied for compounds like RE2O3 [33][34][35][36][37][38][39][40][41], RE2S3 [42][43][44][45][46][47], RE (OH)3 [48][49][50][51][52] and REPO4 [53][54][55][56][57][58][59][60][61][62][63][64]. …”