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Sodium Bromide

 

Crystal: NaBr

Structure: NaCl

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Lattice formation energy:

-7.53 eV.

Lattice parameter:

2.98 Å (2.954 at 0K.)

Density:

3.299 g/cm3 at 4K.

 

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

 

c11: 3.970 (4.800 at 4K.) (Ref.1)

c12: 1.001 (0.986 at 4K.)

c44: 0.998 (1.070 at 4K.)

 

Compressibility (in 1011 dynes/cm2): 0.5023 ??

Poisson ratio:

 

Debye temperature: 225 K

Melting temperature: K

 

Phonon spectrum discussed by:

J.S. Reid & T. Smith, Phonon frequencies in NaBr, Phys. Rev. B1, 1833 (1970)

 

Transverse optic phonon T0 (k=0): 134 or 146 cm-1

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

 

Gruneissen constant:

Ratio e*/e: 0.69

 

Photoelastic constants:

p11:

p12:

p44:

 

 

Band gap:

direct: 7.1 eV. at K

indirect: eV. at ° K

 

Plasmon energy: 14.2 eV.

Exciton energy:

7.7 eV. (Ref.2)

6.71 eV. (Ref.3)

 

Electronic band structure of the alkali halides. II: Critical survey of theoretical calculation, R.T. Poole, J. Liesegang, R.C.G. Leckey & J.G. Jenkin, Phys. Rev. B11, 5194 (1975) which gives:

Valence band width:

3.8 eV.

Gap:

7.5 eV.

Electron affinity:

0.4 eV.

 

Band structure discussed by:

A. B. Kunz, N. O. Lipari, Electronic structure of NaBr, Phys.Rev. B4, 1374 (1971)

 

Static dielectric constant: 5.78

Optic dielectric constant: 2.64

 

Electron mobility:

Hole mobility:

Polaron coupling constant: a = 5.0 ( for m*=1 )

Effective mass: conduction band:

valence band:

 

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

3.51, by Mott-Gurney, maybe 3eV. too high (Ref.4)

 

Spin-orbit coupling: 0.52 ( valence band) (Ref.5)

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Other information:

 

 

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References:

 

  1. J.T. Lewis, A. Lehoczky & C.V. Briscoe. Elastic constants of the Alkali Halides at 4.2K Phys.Rev. 161, 877 (1967)

    2.  

  2. Journal de Physique et le Radium, 28 (1981)

    3.  

  3. W.B. Fowler, "Physics of Color Centers", New York: Academic Press (1968)

    4.  

  4. N.F. Mott & R.W. Gurney, "Electronic processes in Ionic crystals", 2nd. Edition (1950)

    5.  

  5. J.E. Eby, K.J. Teegarden & D.B. Dutton, Ultraviolet absorption of alkali halides Phys.Rev. 116, 1099 (1959)

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