Lutetium heat capacity

Abstract. One more method of study of the short-range order kinetics of H-atoms over tetrahedral interstices in lutetium (Lu) is proposed. It can be realized by the using of available data of measurements of heat capacity for h.c.p.-Lu-H interstitial solid solutions during the isothermal annealing. Comparison of estimated-parameters data from heat capacity and residual electrical-resistivity measurements is performed. It is shown that kinetics of heat capacity and residual resistivity at low temperatures is caused by the unique nature (short-range order relaxation) and can be described by two relaxation times at least. 

This work is concerned with a further analysis of the short-range order kinetics of hydrogen (H) atoms at tetrahedral interstices in h.c.p. lattice of lutetium (Lu). We compare the results obtained from independent investigation methods for different characteristics—residual electrical resistance [4,5] and heat capacity [6], and reveal the same nature of their conditionality. 

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). 

As shown in Table I, lanthanum and lutetium oxides have Sq ground states and consequently their heat capacities should be attributed to lattice vibration. Data on these substances may be used to represent the lattice contribution to a first approximation for neighboring isostructural (and nearly so) sesquioxides. Cubic gadolinium oxide provides a midseries lattice heat capacity approximation at relatively high temperatures... 

The effect of chemical pressure on YbPtBi single crystals was studied by heat-capacity measurements on yttrium- and lutetium-doped samples (Lacerda et al. 1993). According to these measurements, the heavy-fermion state of this compound seems to be imchangeable by a relatively large amoimt of nonmagnetic doping (yttrium or lutetium). Furthermore, the heat capacity measurements reveal only a small pressure dependence when compared with other heavy-fermion materials. 

In their analysis of the heavy lanthanides, Lounasmaa and Sundstrom (1966) used the heat capacity of lutetium as measured by Lounasmaa (1964a) and Culbert (1967) on the same sample. This gave y = 11.27 mJ/mole-K and do(0) = 210 K. The Debye temperature drops rapidly above 4K to a minimum of 158 K at approximately 25 K (Culbert, 1967). 

Feber and Herrick have used experimental, and in some instances predicted, energy-level data for the calculation of the free energy and enthalpy functions , entropy, and heat capacity of the gaseous monatomic lanthanide elements from cerium to lutetium and the gaseous monatomic actinide elements from thorium to curium over the temperature range 100 to 6000 K. 

The heat capacity from -267 to 27°C (60 to 300 K) of 9.65 at% Er-Lu alloy has been measured by Taylor et al. (1972) using an adiabatic calorimeter and a platinum resistance thermometer. The metals used in preparing the alloy were vacuum sublimed in tantalum at 10 torr and 1600°C for lutetium and 1400°C for erbium, then analyzed for impurities. The alloy was remelted several times to insure homogeneity, cast to a cylindrical shape and machined. After heat capacity measure-... 

In fact, the contribution of electronic conductivity can be ignored because it is quite small. The major contribution to Cp arises from the lattice (vibrational) component Cy, which varies linearly as a function of molar volume V in a series of isomorphous compounds. For the com-poimds imder study, Cy can therefore be estimated using volume-weighted interpolation (Westrum et al., 1989) and data on isomorphous diamagnetic substances as reference values. For instance, the Cy heat capacities measured for trivalent lanthanum, gadolinium, and lutetium compoimds were used as reference values. Subsequently, the Cm and Csch contributions were determined by subtracting the sum of the Cy and Cd contributions from the experimental Cp values. 

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