PHYSICAL PROPERTIES OF UO$sub 2$ SINGLE CRYSTALS. Quarterly Report No. 6, March 1-June 30, 1963
Several runs have been made to prepare single crystals of UO/sub 2/ for studies of the physical properties. A new method has been developed allowing the preparation of single crystalline material with compositions between UO/sub 2/ and U/sub 4/O/sub 9/. Calculated amounts of UO/sub 2/ and U/sub 3/O/sub 8/ are held in oxygen equilibrium at 1400 deg C for 2 hours. Improvements of the experimental techniques allowed the observation of sintering above a temperature of 1700 deg C. Concerning the study of self-diffusion of U in UO/sub 2/, work has been done on the development of a method for the plane-parallel removal of layers of UO/sub 2/. Precipitates of U/sub 4/O/sub 9/ of various different shapes have been studied in crystals with O/U ratio of 2.006 to 2.01. Fission fragment damage in as grown crystals (O/U = 2.006) and in stoichiometric crystals was observed after slight irradiations (up to 10/sup 16/ nvt). The irradiations were carried out at 20 deg C and at higher temperatures. The thermoelectric power of a few crystals of diffeient excess oxygen content has been determined as a function of temperature (100 to 600 deg K). The electrical conductivity of single crystals of UO/sub 2/ with O/U ratios of 2.000 to 2.06 has been measured after successive periods of exposure (up to 1.6 x 10 /sup 7/ thermal neutrons/cm/ sup 2/). The conductivity of the oxidized crystals decreases markedly upon irradiation and reaches a saturation value at about 4 x 10/sup 15/ fissions per cm/sup 3/, whereas the conductivity of the stoichiometric specimen remained practically unchanged up to 1.6 x 10/sup 16/ fissions per cm/sup 3/. A study has been made of the validity of the Low, Lee, and Pine's method in the case of the interaction of an electron with a single lattice oscillator. The results of this study are reviewed. A few remarks are given about the conduction mechanism in uranium dioxide. Measurements of the thermal conductivity from liquid helium temperature to about 200 deg K and at 290 deg K indicate the existence of a minimum value at about 180 deg K. (auth)
- Research Organization:
- Centre d'Etude de l'Energie Nucleaire, Mol, Belgium
- NSA Number:
- NSA-18-008719
- OSTI ID:
- 4096754
- Report Number(s):
- EURAEC-746
- Country of Publication:
- United States
- Language:
- English
Similar Records
THE DEPENDENCE OF THE THERMAL CONDUCTIVITY OF URANIUM DIOXIDE ON DENSITY, MICROSTRUCTURE, STOICHIOMETRY AND THERMAL-NEUTRON IRRADIATION
PHYSICAL PROPERTIES OF UO$sub 2$ SINGLE CRYSTALS. Quarterly Report No. 5, October 1, and December 31, 1962
Related Subjects
CRYSTALS
DIFFUSION
ELECTRIC CONDUCTIVITY
FISSION PRODUCTS
HIGH TEMPERATURE
LAYERS
LOW TEMPERATURE
MEASURED VALUES
METALS, CERAMICS, AND OTHER MATERIALS
MONOCRYSTALS
OXYGEN
PREPARATION
QUANTITATIVE ANALYSIS
QUANTITY RATIO
RADIATION DOSES
RADIATION EFFECTS
REACTION KINETICS
SINTERING
TEMPERATURE
THERMAL NEUTRONS
THERMOELECTRICITY
URANIUM
URANIUM DIOXIDE
URANIUM OXIDES