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Uranium Dioxide

Crystal: UO2

Structure: fluorite

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Lattice formation energy:

106.7 eV.

Lattice parameter:

2.734 Å (2.36 for nn distance)

Density:

11.1 g/cm3

 

Stiffness constants: in 1011 dynes/cm2, at room temperature

 

c11: 39.6

c12: 12.1

c44: 6.41

Compressibility (in 1011 dynes/cm2): 0.47*1012 dynes/cm2 ??

Poisson ratio:

Sound velocities:

Vl: ~6.0*105 cm/sec. along cube axes

Vt: ~2.4*105 cm/sec. along cube axes

 

Debye temperature: 377 K, or 242.16K. for U, q E=815K. for O

Melting temperature: 3040 ° C

Neel temperature: K

 

Phonon spectrum discussed by:

 

Transverse optic phonon T0 (k=0): 280 cm-1

Longitude optic phonon L0 (k=0): 450 cm-1 (Raman)

 

Gruneissen constant:

Ratio e*/e:

 

Photoelastic constants:

p11:

p12:

p44:

 

 

Band gap: direct: eV.

indirect: eV.

Gap: eV.

First exciton: eV.

Plasmon energy: 19.7 eV.

 

Difference between conductivity and bonding band: 6eV.

Difference between conductivity and SF: 2.7 eV.

Reference:

B.W. Veal, D.J. Lam, X-ray photoelectronic studies of Thorium, Uranium, and their dioxides, Phys. Rev. B10, 4902 (1974)

 

UO2 data - Characteristic energy loss:

Bulk plasmon at 23.3 eV.

Surface at 8.9 and 20.5 eV.

Plasmon energy: 19.7 eV.

Polarisability per ion radical: 2.2 Å*exp3 (correction to plasmon energy)

Interband transition: ~3.6 eV.

Ref.: E.A. Bakulin et al.; Characteristic losses of electron energy in UO2; Sov. Phys. Sol. St.16,1670 (1975)

 

Band structure discussed by:

 

XPS:

C. Klingshirn, E. Ostertag, R. Levy A new emission line in highly excited ZnO at low temperature, Sol. St. Comm. 33, 883 (1980)

which gives: p-d gap: 5 eV; Localised 5F electrons

Coulomb correlation energy: 4.6 eV.

 

Static dielectric constant: 24.0

Optic dielectric constant: 5.3

 

Electron mobility:

Hole mobility:

Polaron coupling constant: a = ( for m*=1 )

Effective mass: conduction band:

valence band:

 

Electron affinity: ( in eV., from bottom of conduction band under vacuum)

 

Spin-orbit coupling: ( valence band)

 

Cation polarisation: Å-3

Anion polarisation: Å-3

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Other information:

 

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