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Calcium Oxide

Crystal: CaO

Structure: NaCl

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Mechanical and structural properties:

Cohesive energy:	eV
Lattice parameter:	2.40 Å

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

c₁₁: 20.2 (Ref.1), or 22(Ref.2), or 22.2(Ref.3), or 27.6(Ref.4), or 20.3(Ref.5)

c₁₂: 7.6 or 5 or 6 or 6.1

c₄₄: 6.1 or 8 or 8.2 or 7.6

or:

c₁₁: 22.62 at 298K. (Ref.6)

c₁₂: 6.24

c₄₄: 8.06

Compressibility (in 10¹¹ dynes/cm²): 0.0847 ??

Poisson ratio: 0.23 (Voigt)

Debye temperature: 648 ° K (Ref.5) (533 and 668 cited too)

Melting temperature: 2572 or 2590 ° C

Phonon spectrum discussed by: Peckham and Saunderson

Transverse optic phonon T0 (k=0):6.88*10exo13/sec., or 295 cm^-1 (Ref.7) Also 290 or 286 (Ref.8)

Longitude optic phonon L0 (k=0): 577 or 564 cm^-1 cited in Ref.7, 538 by LST (Ref.7), or 575, 577 or 568 cited by: Ref.8

Gruneissen constant:

Ratio e*/e:

Photoelastic constants:

p₁₁:

p₁₂:

p₄₄:

Electronic properties:

Band gap: Direct: 7.7 eV (Henderson & Hughes give 6-7 and 7.077 eV (Ref.9))

6.25 (Ref.10); First excitation: 6-8 eV (Ref.10)

Indirect: eV.

Band structure discussed by:

U. Seth and R. Chaney, Energy-band structure of calcium-oxide crystals by the method of tight binding, Phys. Rev. B12, 5923 (1975)

Also: N. Daude, C. Jouamin and C. Gouf, Electronic band structure of magnesium and calcium oxides, Phys. Rev. B15, 2399 (1977)

More information:

Some doubts about direct/indirect ga Predict about 9.5 eV in either case.

See L.F. Mattheiss, Electronic structure of the 3d transition-metal monoxides. I.Energy-band results, Phys.Rev. B5, 290 (1972)

Static dielectric constant: 11.8 or 11.1±0.3 (Ref.11)

Optic dielectric constant: 3.28 or 3.33±0.10

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)

0.7 (Ref.12)

Spin-orbit coupling: ( valence band)

Cation polarisation: 0.478 Å^-3

Anion polarisation: 2.362 Å^-3

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Other information:

R.A. Bartels et al. give:

(de o/dT)p /e o	(de o/dP)t /e o	(de o/dT)v
(in 10^-4/K.)	(in Mbar-1)	(in 10^-4/K.)
MgO 0.98	-1.8	+0.06
CaO 0.83	-2.1	-0.07
SrO 2.46	-2.9	+1.43

Ref.: R.A. Bartels et al., Phys. Stat. Sol. 52, K213 (1979)

Also results for alkali fluorides

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References:

1. Comptes Rendu. B269, 30 (1969)

2. J.A.G. Smith (ceramics)

3. R.A. Bartels and R. Son, CaO and SrO single crystal elastic constants and their pressure dependence, Bull. Am. Phys Soc. 16, 357 (1971)

4. A.J. Pointon, R.G.F. Taylor, Elastic constants of magnesia, calcia, and spinel at 16 GHz and 4.2K.Nature 219, 712 (1968)

5. H.E. Hite, R.J. Kearney, Elastic constants of CaO in the temperature range 80-270K., J. Appl. Phys. 38, 5424 (1967)

6. A.L. Drago and I.L. Spain

The elastic moduli and their pressure and temperature derivatives for Calcium Oxide, J. Phys. Chem. Soc. 38, 705, 1977)

7. J.L. Jacobson and E.R. Nixon, Infrared dielectric response and lattice vibrations of Calcium and Strontium Oxides, J. Phys. Chem. Soc. 29, 967 (1968)

8. J.Phys.Chem.Soc. 32, 2400

10. B. Ulrici, W. Ulrici, N.N. Kovalev, Optical absorption in SrO single crystals, Sov. Phys .Sol. St. 17, 2305 (1976)

11. J.L. Jacobson and E.R. Nixon, Infrared dielectric response and lattice vibrations of Calcium and Strontium Oxides, J. Phys. Chem. Sol. 29, 967 (1968)

12. K.Y. Tsou and E.B. Hensley, Electron affinities of the alkaline earth chalcogenides, J. Appl. Phys. 45, 47 (1979)

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