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Rubidium Iodide

Crystal: RbI

Structure: NaCl

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Mechanical and structural properties:

Lattice formation energy:	-6.28 eV.
Lattice parameter:	3.66 Å (3.628 at 0K.)
Density:	3.55 g/cm³

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

c₁₁: 2.56 (Ref.1) or 3.210

c₁₂: 0.31 or 0.36

c₄₄: 0.29 or 0.292

Compressibility (in 10¹¹ dynes/cm²): 0.943 ??

Poisson ratio:

Debye temperature: 105 K

Melting temperature: K

Phonon spectrum discussed by: Saunderson in MDD Report (~1969)

Transverse optic phonon T0 (k=0): 75 or 81.5 cm^-1

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

Gruneissen constant: 3.18 or 3.29 (Hodby)

Ratio e*/e: 0.89

Photoelastic constants:

p₁₁:

p₁₂:

p₄₄:

Electronic properties:

Band gap:

direct: 6.1 eV. at K

indirect: eV. at ° K

Plasmon energy: eV.

Exciton energy: 5.73 eV. (Ref.2)

Conduction band width: 1.2 eV. ### valence band width? ###

Band structure discussed by:

Static dielectric constant: 5.0 or 4.55 (Hodby)

Optic dielectric constant: 2.63 or 2.61 (Hodby)

Electron mobility:

Hole mobility:

Polaron coupling constant: a = 5.8 ( for m*=1 )

Effective mass: conduction band: 0.365 or 0.39 (Hodby)

polaron mass: 0.72

valence band:

Electron affinity: ( in eV., from bottom of conduction band under vacuum) 0.6 eV. (Ref.3)

Mott & Gurney estimate 3.20 eV. (Ref.4)

Spin-orbit coupling: 0.77 ( valence band) (Ref.5)

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Other information:

Ultraviolet electron spectra of Rubidium halides, C.S. Inouye & W. Pong, Phys.Rev. B15, 2265 (1977)

See also supplementary on RbI

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Supplementary information on RbI:

High-pressure optical absorption and x-ray diffraction studies in RbI and KI approaching the metallization transition.

K. Asaumi, T. Suzuki, and T. Mori. Phys.Rev. B28. 3529 (1983)

The pressure dependence of the fundamental optical absorption edges in RbI and KI crystals has been investigated up to 70 GPa at room temperature by using high-pressure apparatus of sapphire and diamond anvil types. The absorption edges in RbI and KI are found to show some complicated behaviors below ~5GPA within the uv region. Beyond ~5GPa, absorption edges ° monotonically, with increasing pressure up to 70 GPa. The x-ray diffraction study shows that the CsCl-type crystal structure remains stable up to 67 GPa after the NaCl- to CsCl-type phase transition at 0.4 GPa for RbI and at 1.9 GPa for KI, respectively. The metallization pressures of RbI and KI are estimated to be approximately 85 and 115 GPa, respectively.