Determination of the Specific Heat Capacity of RE(Et₂dtc)₃(phen) by Microcalorimetry

Abstract

A calculation formula for determining the specific heat capacity of solid compound with an improved RD496-III microcalorimeter was derived. The calorimetric constant and precision determined by the Joule effect were (63.901±0.030) µV/mW and 0.3% at 298.15 K, respectively, and the total disequilibrium heat has been measured by the Peltier effect. The specific heat capacities of two standard substances (benchmark benzoic acid and α-Al 2 O 3 ) were obtained with this microcalorimeter, and the differences between their calculated values and literature values were less than 0.4%. Similarly, the specific heat capacities of thirteen solid complexes, RE(Et 2 dtc) 3 (phen) (RE＝La, Pr, Nd, Sm-Lu, Et 2 dtc: diethyldithiocarbamate ion, phen: 1,10-phenanthroline) were gained, and their total deviations were within 1.0%. These values were plotted against the atomic numbers of rare-earth, which presents tripartite effect, suggesting a certain amount of covalent character in the bond of RE 3＋ and ligands, according to Nephelauxetic effect of 4f electrons of rare earth ions.

Thermochemical Study of the Solid Complexes Ln[(CH3)2NCS2)]3(C12H8N2) (Ln = Eu, Gd, Tb, Dy)

“…The molar specific heat capacities of the complexes were measured according to ref (measuring six times for each sample), and their molar specific heat capacities were calculated from the data in Table and presented in Table .…”