Holmium heat capacity

Lanthanide (III) Oxides. The lanthanide(III) oxides will be used to illustrate the present breadth of our most extensive knowledge of the chemical thermodynamics of lanthanide compounds. Cryogenic heat capacities of hexagonal (III) lanthanum, neodymium, and samarium oxides, together with those of cubic (III) oxides of gadolinium, dysprosium, holmium, erbium, and ytterbium, have been reported (90, 91, 195). In addition, those of thulium, lutetium, and a composition approaching that of cerium (III) oxide have also been determined, and five well-characterized compositions between PrOi.714 and PrOi.833 are currently under study (J93). 

A complex of holmium perchlorate coordinated with 1-glutamic acid was prepared with a purity of 98.96%. The compound was characterized by chemical, elemental and thermal analysis. Molar heat capacities of the compound were determined by a high-precision automated adiabatic calorimeter from 78 to 370 K. The dehydration temperature, dehydration enthalpy, entropy and the standard enthalpy of formation were reported [183],... 

A Ho(PDC)3(o-phen) complex has been obtained and studied by Xie et al. [184] from the reaction of hydrated holmium chloride, ammonium pyrrolidinedithiocarbamate (APDC) and 1,10-phenanthroline (o-phen-H20) in absolute ethanol. The enthalpy of complex formation from a solution of the reagents and the molar heat capacity of fre complex were determined by using a heat conduction microcalorimeter. The enthalpy of complex formation from the reaction of the reagents in the solid phase, was calculated on the basis of an appropriate thermochemical cycle and other auxiliary thermodynamic data. The thermodynamics of formation of the complex were investigated by the reaction in solution at the temperature range of 292.15 - 301.15 K. The constant-volume combustion energy of the complex, Act/, was also determined. 

Even at 4 K the nuclear contribution dominates the heat capacity of holmium by about 85%. Thus Krusius et al. (1969) in measurements below 0.6 K were essentially looking at Cn only, and obtained the hyperfine interaction parameters given in table 5.2. These parameters agree fairly well with those of van Kempen et al. (1964), whose Cn results showed considerably more scatter, although Krusius et al. (1969) felt that the fit to their own results was not as good as for the other lanthanides they have measured. The results of NMR (Mackenzie et al. 1974) give slightly lower parameter values. 

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