THE NATURE OF NONSTOICHIOMETRY IN URANIA-BASE SOLID SOLUTIONS

Technical Report · Wed Mar 01 04:00:00 EST 1961

OSTI ID:4805488

Aronson, S; Belle, J

Measurements of the electrical conductivity and thermoelectrie pow er of nonstoichiometric uranium dioxide confirm the ionic description of nonstoichiometry in urania-base fluorite structures suggested on the basis of thermodynamic measurements and lattice energy calculations. Nonstoiochiometric urania-base solid solutions appear to be relatixely simple ionic solids containing U/sup 5+/ ions and interstitial O/sup 2-/ ions. The U/sup 4+/, U/sup 5+/ and substitutional cations (Th/sup 4+/, Zr/sup 4+/, Y/sup 3+/) may be considered to be randomly distributed in the cationic lattice. The specific electrical conductance, sigma /sub 0/, of nonstoichiometric uranium dioxide is adequately described by the equation sigma /sub 0/ = (3.8 x 10/sup 6//T) exp (-- 0.30 + 0.03/kT) STAU/sup 5+/! STAU/sup 4+/! where STAU/sup 5+/! an d STAU/sup 4+! are the concentrations of U/sup 5+/ and U/sup 4+ ions, respectively. The thermoelectric power, Q, for nonstoichiometric uranium dioxide is approximately represented by the equation Q = (k/e) ln STAU/sup 4+!/STAU/sup 5+! where k is Boitzmann's constant aid e is the electronic charge. Both equations are consistent with a simple ionic description in which activated electronic transfer occurs between U/sup 4+/ and U/sup 5+/ ions in the lattice. Other properties of uranium dioxide which were measured, such as magnetic susceptibility and oxygen diffusion, are briefly discussed in the light of the ionic model for UO/sub 2/. (auth)

• Research Organization: Westinghouse Electric Corp. Bettis Atomic Power Lab., Pittsburgh
• DOE Contract Number: AT(11-1)-GEN-14
• NSA Number: NSA-16-005397
• OSTI ID: 4805488
• Report Number(s): WAPD-T-1294
• Country of Publication: United States
• Language: English

Related Subjects

ATOMIC MODELS
BOLTZMANN CONSTANT
CALCIUM FLUORIDES
CATIONS
CHEMICAL REACTIONS
CHEMISTRY
DIFFUSION
DISTRIBUTION
ELECTRIC CONDUCTIVITY
ELECTRONICS
EQUATIONS
FLUORITE
HYDROXIDES
IONS
LATTICES
MEASURED VALUES
MINERALS
NUMERICALS
OXYGEN
POWER
QUANTITY RATIO
SOLID SOLUTIONS
SUSCEPTIBILITY
THERMODYNAMICS
THERMOELECTRICITY
TRANSFER FUNCTIONS
URANIUM
URANIUM DIOXIDE
URANIUM OXIDES