_____________________________________________________________________

 

Silver Chloride

Crystal: AgCl

Structure: NaCl

_____________________________________________________________________

 

 

Lattice formation energy:

-8.82 eV. (theory, Mayer and al.) (Ref.1)
 

-8.93 eV. (experimental) (Ref.1)

Lattice parameter:

2.775 Å

Density:

g/cm3

 

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

 

c11: 7.590 or 6.01 (Ref.2)

c12: 3.908 or 3.62

c44: 0.6894 or 0.63

Compressibility (in 1011 dynes/cm2): 0.194 ??

Mixed AgCl-AgBr: elastic constants:

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

Elastic constants of Silver Chloride from 4.2 to 300K., W. Hidshaw, J.T. Lewis & C.V. Briscoe, Phys.Rev. 163, 876 (1967)

 

Poisson ratio:

 

Debye temperature: 215 K (Ref.3) or 161.3 K (Ref.4)

Melting temperature: K

 

Phonon spectrum discussed by:

C-K. Chang & M.V. Klein, Phonon scattering from substitutional impurities & lattice defects in Silver Chloride, Phys. Rev. B1, 2650 (1970)

See also Ref.5, 6, 7, 8

 

Transverse optic phonon T0 (k=0): 103 cm-1 (Ref.1)

Longitude optic phonon L0 (k=0): 181 cm-1 or 197 cm-1 (Hodby)

Gruneissen constant:

Ratio e*/e:

Polaron radius: 12.5 Å

 

Photoelastic constants:

p11:

p12:

p44:

 

 

Band gap:

direct: eV. at K

indirect: 3.25 eV. at ° K

 

Plasmon energy: eV.

Exciton energy: 3.2468 eV. (L) and 3.2640 eV.(Delta) (Ref.10)

or 5.10 eV. (Gamma) and 6.25 eV.(L) (Ref.11)

 

Band structure discussed by: See Other Information, below

 

Static dielectric constant: 9.50 (Hodby)

or 9.55 at 2K. and 11.05 at 255K. (Ref.12)

 

Optic dielectric constant: 3.97 (Hodby) or 4.29 or 3.92 (Ref.11)

 

Electron mobility:

Hole mobility:

Polaron coupling constant: a = 1.91 ( for m*=1 )

 

Effective mass:

conduction band: polaron band: 0.431 (Hodby) (parallel), 0.303 (perpendicular)

valence band:

 

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

 

Spin-orbit coupling: ( valence band)

_____________________________________________________________________

 

Other information:

 

 

_____________________________________________________________________

 

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. R.M. Niclow & R.A. Young, Thermal expansion of AgCl, Phys.Rev. 129, 1936 (1963)

    4.  

  4. W.T. Berg, Low temperature heat capacities of Silver Chloride & Lithium Iodide, Phys.Rev. B13, 2641 (1976)

    5.  

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

    6.  

  6. G.O. Jones, D.H. Martin, A. Mawer & C.H. Perry, Spectroscopy at extreme infra-red wavelengths. II: the lattice resonances of ionic crystals, Proceeding Roy.Soc. A261, 10 (1961)

    7.  

  7. Phys.Rev. ViJapyaraghavan, R.M. Niclow, H.G. Smith & M.K. Wilkinson, Lattice dynamics of Silver Chloride, Phys. Rev. B1, 4819 (1970)

    8.  

  8. G.L. Bottger & A.L. Geddes, Infrared lattice vibrational spectra of AgCl, AgBr & AgI, J. Chem .Phys. 46, 3000 (1967)

    9.  

  9. R.H. Stulen & G. Ascarelli, Temperature dependence in the indirect absorption edge in AgCl: Evidence of a new source of non-polarisability in the indirect exciton dispersion, Phys. Rev. B13, 5501 (1976)

    10.  

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

    11.  

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

_____________________________________________________________________

 

Additional information on AgCl:

Second-order elastic constants of AgCl from 20 to 430 ° C.

C. Hughes and L.S. Cain, Phys. Rev. B (1984)

 

The three independent adiabatic second-order elastic constants of AgCl have been measured from 20 to 430 ° C using the McSkimin pulse-superposition technique. Two single crystals with (110) and (001) axes were used in the measurements. Measurements on the (110) crystal gave the complete set of constants and showed that the Longitude optic phonon elastic constant C’11 = (C11 + C12 + 2C44)/2 ° by 37%, the shear constant C44 ° by 15%, and the shear constant C’ +(C11-C12)/2 ° by 65% over this temperature range. The Longitude optic phonon elastic constant C11 ° by 45%, the elastic constant C12 ° by 31% and the Bulk modulus Bs= (C11+2C12)/3 ° by 37%. The (001) crystal was used as a check on the consistency of the measurements. The ° in the elastic constants are linear, as expected, until approximately 320 ° C, whereupon C’11, C44, C11, C12, and Bs begin to ° more rapidly than linearly and are 6.8, 0.8, 6.0, 9.2, and 8.0 %, respectively, below the expected linearity at 430 ° C. By contrast, the shear constant C’ ° linearly over the entire temperature range. The elastic constant behavior thus becomes anomalous near the melting point, just like many of the other physical properties of the silver halides. This anomalous behavior may be attributed to the unusually high defect concentration near the melting point. Similar changes in elastic constants are seen in superionic conductors near the transition into the superionic state: a large ° in C11, but only small changes in C44. This may indicate that the silver halides are just starting the transition to the superionic state when the halide sublattice melts and the transition is frustrated.

_____________________________________________________________________