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Magnesium Oxide

Crystal: MgO

Structure: NaCl

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Mechanical and structural properties:

Cohesive energy:	-40.06 eV
Lattice parameter:	3.5761 g/cm³
Density:

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

c₁₁: 28.6 (Ref.1) or 29.2 (Ref.2) or 31.2 (Ref.3)

c₁₂: 8.7 or 9.1

c₄₄: 14.8 or 15.4

Third order elastic constants: (in 10¹¹ dynes/cm²) (Ref.4)

c₁₁₁: -489.5 c₁₁₂: -9.5 c₁₂₃: -6.9

c₁₄₄: +11.3 c₁₆₆: -65.9 c₄₅₅: +14.7

Compressibility (in 10¹¹ dynes/cm²): 0.0652 ??

Poisson ratio: 0.172 (Voigt)

Sound velocity: 9.15.10⁵ cm/sec. for L and 6.62.10⁵ cm/sec. for T

Debye temperature: 941 ° K (See Ref.5 for q (Debye) versus T)

Melting temperature: 2800 ° C

Phonon spectrum discussed by:

R.K. Singh and K.S. Upadhyaya, Crystal dynamics of Magnesium Oxide, Phys. Rev. B6, 1588 (1972)

M.J.L. Sangster, G. Peckham and D.H. Saunderson, Lattice dynamics of Magnesium Oxide, J.of Phys. C3, 1026 (1970)

Transverse optic phonon T0 (k=0): 400±2 cm^-1 (Ref.6)

Longitude optic phonon L0 (k=0): 721±4 cm^-1 (Ref.6)

Gruneissen constant:

Ratio e*/e:

Photoelastic constants:

p₁₁: -0.21 or -0.31 or -0.259 (Ref.7)

p₁₂: 0.04 or -0.07 or -0.011

p₄₄: -0.10 or -0.105

Electronic properties:

Band gap:

Direct: 8.7 eV. (7.77 later) (Henderson & Hughes cite 7.3, 7.8 or 8.7)

7.6-7.75 eV at the edge (Ref. 8)

Indirect gap: eV.

Surface plasmon: 14.7 eV (Ref.9)

Bulk plasmon: 22 eV (Ref.9)

Band Gap Eg: 7.16 eV (Ref.10)

First excitation: 7.69 or 7.76 eV (Ref.10)

Valence band width: 6.5 eV (Ref.11)

Valence band width, see, for summary:

S. Kowalczyk et al., The electronic structure of SrTiO3 and some simple related oxides (MgO, Al2O3, SrO, TiO2), Sol.St.Com. 23,163 (1977)

Also: F. Walch and D.E. Ellis, One-electron interpretation of optical absorption and soft-x-ray data in MgO, Phys. Rev. B8, 5920 (1973)

For UV reflectance data: see Phys. Rev. B7, 3810 (1973)

Band structure discussed by:

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

Also: S.T. Pantelides, D.J. Mickish and A.B. Kunz, Electronic structure and properties of magnesium oxide, Phys. Rev. B10, 5203 (1974)

More: MgO: Approximative self-consistent scheme:

I.V. Abarenkov, I.M. Antonova, The electronic structure of MgO. I. Calculation method, Phys. Stat. Sol. 92, 389 (1979)

And: Atomic change densities in MgO, CaO, SrO, BaO.

Charge deformation of O ion:

G. Vilda-Valat, J. Vidal, K. Kuri-Suonio, X-ray study of the atomic charge densities in MgO, CaO, SrO and BaO, Acta Cryst. A34, 594 (1978)

Charge distribution in O^2- anion in MgO, CaO:

J. Redinger and K. Schwartz, Electronic charge distribution of the polarizable O2- ion in MgO and CaO in contrast to the F- ion in NaF, Zeitschrift fur Phys. B40, 269 (1981)

Core levels, etc.:

XPS: N.C. Halders, J.Alonso and W.E. Swartz, Valence and core electron spectra of Mg in MgO in evaporated thin films; Z.fur Naturf. 30A, 1485 (1975)

Electron-loss: V.E. Henrich, G. Dresselhaus, Evidence for localised excitations in MgO from electron energy-loss spectroscopy, Sol. St. Com. 16, 1117 (1975)

Static dielectric constant: 9.8 or 9.65 (Ref. Henderson & Hughes) or 9.830 at 300K. (Ref.12)

Optic dielectric constant: 2.95 (Ref.Henderson & Hughes)

Temperature and pressure dependence:

R.A. Bartels and A. Smith, Pressure and temperature dependence of the static dielectric constants of KCl, NaCl, LiF and MgO, Phys.Rev. B7, 3885 (1973)

For more information:

K. Hishano and K. Toda, J.Phys. C15, 1115 (1982), Optic modes of MgO-Temperature dependence in thin films from thermal emission spectra.

Seem to get w L and w T up to 1400 ° K. without problems.

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)

<~ 1.0 (Ref.13); ~ 1.0 (Ref.14) BUT: -4 to -2.5 eV (Ref.17, also some Japanese analysis)

MgO, c = +0.85 eV K.Y. Tsou and E.B. Hensley, Electron affinities of the alkaline earth chalcogenides, J.Appl.Phys.45,47 (1979)

MgO, c = +0.8 eV R.E. Thomas, J.W. Gibson, G.A. Haas

Spin-orbit coupling: ( valence band)

Cation polarisation: 0.096 Å^-3 Anion polarisation: 1.647 Å³

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Other information:

Pressure dependence: J. Am. Ceramics Soc. 49, 404 (1966)

Carbon in MgO:

F. Freund et al., Atomic carbon in magnesium oxide. Part I: Carbon analysis by the 12C(d, p)13C method, Mat.Res.Bulletin 15, 1011 (1980)

Also: F. Freund, G. Debras, G. Demortier, Carbon content of MgO single crystals grown by the arc fusion method, J.Cryst.Growth 38, 277 (1977)

Also: F. Freund, G. Debras, G. Demortier, Carbon content of High-Purity Alkaline Earth Oxide. Single crystal grown by arc fusion, J. Am. Ceram. Soc. 61, 429 (1978)

Radiation damage: Mg²⁺ displacement energy: 64±2 eV (Ref.15) O^2- displacement energy: 60±2 eV (Ref.16)

See also supplementary information about MgO and bandstructure of MgO, below

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References:

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

4. E.H. Bogardus. Third-order elastic constants of Ge, MgO, fused SiO2, J. Appl. Phys. 36, 2504 (1965)

5. T.H.K. Barron, W.T. Berg and J.A. Morrison On the heat capacity of crystalline magnesium oxide Proc .Royal Soc. 250A, 70 & 83 (1959)

6. J. Phys. Chem. Sol. 32, 2400

7. K.G. Aggaewal and B. Szigeti Photoelastic constants and the Clausius-Mossoti field in the alkali halides J.Phys. C3, 1097 (1970)

8. Sov.Phys.:JETP Letter 22, 36 (1975)

9. R.L. Hengehold, F.L. Pedrotti, Plasmon excitation energies in ZnO, CdO, MgO, J.Appl.Phys. 47, 287 (1976)

10. B. Ulrici, W. Ulrici, N.N. Kovalev, Optical absorption in SrO single crystals, Sov.Phys.Sol.St. 17, 2305 (1975)

11. S. Kowalczyk et al., The electronic structure of SrTiO3 and some simple related oxides (MgO, Al2O3, SrO, TiO2), Sol.StatesCom. 23, 163 (1977)

12. J. Fontanella, C. Andeen, and D. Schuele Low-frequency dielectric constants of alpha-quartz, sapphire, MgF2 and MgO .Appl.Phys. 45, 2852 (1974)

13. J. Yamashita, Oxygen band in Magnesium Oxide, Phys.Rev. 111, 733 (1958)

14. J.R. Stevenson, E.B. Hensley, Thermionic and photoelectric emission from MgO, J.Appl.Phys. 32,166 (1961)

15. Rad. Effects. 17, 65 (1973)

16. Y. Chen, D.L. Truebloods, O.E. Schow and H.T. Tohver, Colour centres in electron irradied MgO, J.of Phys. C3, 2501 (1970)

17. A.M.Stoneham, M.J.L.Sangster, Phil.Mag. B43, 609 (1980)

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Supplementary information on MgO

High-pressure behaviour of MgO: Structural and electronic properties.

K.J. Chang and M.L. Cohen

The high-pressure behaviour of the structural and electronic properties of MgO is examined with use of the pseudopotential method within local-density theory. At zero pressure, the rocksalt phase is found to be lower in energy than a hypothetical CsCl structure. However, we predict a phase transformation into an insulating CsCl structure at a very high hydrostatic pressure of about 10 Mbar. This result predicts that the CsCl phase for MgO is unlikely to exist even in the lower mantle of the Earth. The calculated ground-state properties such as lattice constant, bulk modulus, and cohesive energy for the rocksalt phase are in good agreement with experiment. The electronic band structures at normal and high pressures are also given.

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