_____________________________________________________________________

 

Silver Bromide

 

Crystal: AgBr

Structure: NaCl

_____________________________________________________________________

 

 

Lattice formation energy:

-8.56 eV. (theory, Mayer and al.) (Ref.1)
 

-8.77 eV. (experimental) (Ref.1)

Lattice parameter:

2.884 Å (Ref.2)

Density:

6.47 g/cm3 (Ref.2)

 

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

 

c11: 5.62 (Ref.2)

c12: 3.28

c44: 0.73

Compressibility (in 1011 dynes/cm2): 0.246 ??

Poisson ratio:

 

Mixed AgCl/AgBr elastic constants:

The elastic constants & their temperature and pressure derivatives of AgBr-AgCl mixed crystals, L.S. Cain, J.Phys.Chem.Solids 38, 73 (1977)

 

Debye temperature: K

Melting temperature: K

 

Phonon spectrum discussed by:

K. Fischer, H. Biltz, R. Haberkorn & W. Weber, Covalency & deformability of Ag+ ions in the lattice dynamics of Silver halides, Phys.Stat.Sol. 54, 285 1972)

(Includes covalency & shell model)

Also: Y. Fujii, S. Hoshino, S. Sakuragi & H. Kanzaki, Neutron scattering study of the lattice dynamics of AgBr at 4.4K., Phys. Rev. B15, 358 (1977)

Also: See Bloch thesis for earlier work

Phonons studies:

Excitons & phonons in mixed Silver halides studied by resonant Raman scattering, A. Fujii, H. Stolz & W. von der Osten, J.Phys. C16, 1713 (1983)

Note: for Cl/Br, inversion of at L point

 

Transverse optic phonon T0 (k=0): ~140 cm-1 (Not the 119 cm-1 assumed by Brandt & Brown)

Longitude optic phonon L0 (k=0): 132 cm-1 (Hodby)

Gruneissen constant:

Ratio e*/e: 0.73

 

Photoelastic constants:

p11:

p12:

p44:

 

 

Band gap:

direct: 4.25 eV. (L) , 6.14 eV. (Gamma)

indirect: 2.68 eV. at ° K

 

Plasmon energy: eV.

Exciton energy: 4.25 eV. (Gamma) at 20K. (Ref.3), 6.1 eV. (L) at 20K.

Stolz & Wassmuth give also:

g(c)= 1.46 eV

g(v)= 2.61 eV

 

Exchange : 0.17 meV.

Indirect exciton B.E.: 32 meV.

Indirect Gap: 2.8 eV. (Cond. band at zone centre, Valence band at L point)

Direct Gap: 4.29 eV.

 

Band structure discussed by:

H. Stolz, W. Wassmuth, W. von der Osten & C. Uihlein, Resonant Raman scattering at the indirect triplet exciton in AgBr in high magnetic fields, J. Phys. C16, 955 (1983)

 

Photoemission:

Silver-halide valence & conduction states: temperature-dependence ultraviolet emission studies, R.S. Bauer & W.E. Spicer, Phys.Rev. B14, 4539 (1976)

 

Static dielectric constant: 10.60 (Hodby) or 10.64 at 2K. and 12.64 at 255K. (Ref.4)

Optic dielectric constant: 4.68 (Ref.3)

 

Electron mobility:

Hole mobility:

Polaron coupling constant: a = 1.60 ( for m*=1 ) (Hodby) a = 1.57 (Latev)

Effective mass:

conduction band: m*(e): 0.288 (ref 5)

valence band: m*(h): 1.123 (ref 5)

 

Exciton mass: 0.229 (Ref.5)

Polaron radius: 17 Å

Deformation potential: ~2 eV.

 

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

 

Spin-orbit coupling: 0.6 eV. ( valence band)

_____________________________________________________________________

 

References:

 

  1. C. Kittel, "Introduction to Solid State Physics", 2nd. Edition, New York: Wiley (1956)

    2.  

  2. Ted R. Musgrave, "Understanding problems for chemical principles", Philadelphia: Saunders (1978)

    3.  

  3. A. Marchetti & G. L. Bottger, Optical absorption spectrum of AgF, Phys.Rev. B3, 2604 (1971)

    4.  

  4. Digest of literature on Dielectrics. 2. Tables of Dielectric constants. 37, 18 (1973)

    5.  

  5. H. Stolz, W. Wassmuth, W. von der Osten & C. Uihlein, Resonant Raman scattering at the indirect triplet exciton in AgBr in high magnetic fields, J.of Phys. C16, 955 (1983)

_____________________________________________________________________