No abstract

Measurements of the vapor density in equilibrium with molybdenum trioxide and uranium oxide (U,Os) have been performed by means of the transpiration method with oxygen employed as a carrier gas. The standard free energy of sublimation in calories per mole of gas for molybdenum trioxide is given over the temperature range 980 to 1060°K. by the equation AF°, = (87.8 ± 1.0) 10* -(73.0 ± 1.0) T cal. mole-1, in which the polymeric species in the vapor are recognized. In the case of uranium oxide variation of the oxygen pressure in the carrier gas establishes the oxygen-to-uranium ratio equal to three for the volatile uranium oxide molecule. By a comparison with the entropies of sublimation of molybdenum and tungsten trioxides it is inferred that gaseous monomeric uranium trioxide is the principal species produced by the reaction of U«0« with oxygen. Although the vapor may not consist entirely of monomer, the standard free energy of formation in calories per mole of this gas over the temperature range 1230-1700°K. can be expressed by the equation AF°t = -198,500 + 19.0T cal. mole-1.

This report waa prepared as an account of Government Bponaored work. Neither the United States, nor the Commission, nor any person acting on behalf of the Commission A Makes any warranty or representation, expressed or implied, with respect to the accuracy, completeness, or usefulness of the information contained in this report, or that the use of any information, apparatus, method, or process disclosed in this report may not infringe privately owned rights, or B Assumes any liabilities with respect to the use of, or for damages resulting from the use of any Information, apparatus, method, or process disclosed in this report. As used in the above, "person acting on behalf of the Commission" includes any employee or contractor of the Commission, or employee of such contractor, to the extent that such employee or contractor of the Commission, ot employee of such contractor prepares, disseminates, or provides access to. any informatloti pursuant to his employment or contract with the Commission, or his employment with such contractor AEC Contract No. W 7405-eng-92 Report No. BMI-1789 UC-25 Metals, Ceramics and Materials CFS« nsCBA ac. »

No abstract

The thermal diffusivity of plutonium metal has been measured from room temperature to 822K by the laser-flash method, and the thermal conductivity has been calculated using literature data for the other parameters. Linear fits of the conductivity to temperature have been provided for all the phases with the exception of δ′. A simple quadratic fit, suitable for rough estimates, for all the higher-temperature phases other than δ′ is also given. The results are compared with measurements of the electrical resistivity in the same region, and are discussed in terms of contemporary theories of the electronic structure of the material in its various phases.