NSM Archive - Aluminium Nitride (AlN) - Mechanical Properties, Elastic Constants, Lattice Vibrations
Mechanical Properties, Elastic Constants, Lattice Vibrations
Basic ParametersElastic Constants
Acoustic Wave Speeds
Phonon Frequencies
Frequencies and Symmetries of the Strongest Modes
Basic Parameters
| Remarks | Referens | ||
| Density | 3.255 g cm-3 3.23 g cm-3 |
X-ray |
Slack (1973) Goldberg (2001) |
| Surface microhardness on basal plane (0001) |
800 kg mm-2 | 300 K, using Knoop's pyramid test | Nikolaev et al. (1998) see also Drory et al. (1996) |
Elastic constants at 300 K.
Wurtzite AlN. Elastic constants at 300 K.| C11 | 410 ± 10 GPa | McNeil (1993) see also Wright (1997) |
| C12 | 149 ± 10 GPa | |
| C13 | 99 ± 4 GPa | |
| C33 | 389 ± 10 GPa | |
| C44 | 125 ± 5 GPa |
| Wurtzite AlN. Bulk modulus (compressibility-1) | For T = 300 K |
| Bs = [ C33(C11 + C11) - 2(C13)2] x [C11+ C12-4C13+ 2C33 ]-1 | Bs = 210 GPa |
| Young modulus, Y0 | 308 GPa | Gerlich et al. (1986) |
Poisson ratio, σ0 along the different crystallographic directions |
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| {0001}, c-plane | 0.287 | Thokala & Chaudhuri (1995) |
| {1120}, r-plane (l = <0001>, m = <1100>) | 0 | |
| {1120}, r-plane (l = <1100>, m = <0001>) | 0.216 | |
The sound velocities and related elastic module (experimental data) |
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| The velocity of the longitudinal waves, vl | 10,127 m s-1 | Gerlich et al. (1986) |
| The velocity of the shear waves, vs | 6,333 m s-1 | |
| The longitudinal elastic modulus, CL | 334 GPa | |
| The shear elastic modulus, Cs | 131 GPa |
Temperature derivatives of the elastic module
dlnCL / dT = -0.37 x 10-4 K-1;
dlnCs / dT = -0.57 x 10-4 K-1;
dlnBs / dT = -0.43 x 10-4 K-1
Acoustic Wave Speeds
Wurtzite crystal structure
| Wave propagation direction | Wave character | Expression for wave speed | Wave speed (in units of 105 cm/s) |
| [100] | VL (longitudinal) | (C11/ρ )1/2 | 11.27 |
| VT (transverse, polarization along [001]) | (C44/ρ )1/2 | 6.22 | |
| VT (transverse, polarization along [010]) | ((C11-C12)/2ρ )1/2 | 6.36 | |
| [001] | VL (longitudinal) | (C33/ρ )1/2 | 10.97 |
| VT(transverse ) | (C44/ρ )1/2 | 6.22 |
Wurtzite crystal structure
The cristalografic direction you can see Band structurePhonon frequencies
Wurtzite crystal structure
| phonon wavenumbers: | Remarks | Referens | |
| νTO(E1) | 895(2) cm-1 |
RT. Raman scattering | Sanjurjo et al. (1983) |
| νLO(E1) | 671.6(8) cm-1 | ||
| νTO(A1) | 888(2) cm-1 | ||
| νLO(A1) | 659.3(6) cm-1 | ||
| ν(E2) | 303 cm-1 | Raman scattering, tentative assignment | Carlone, et al. (1984) |
| ν(E2) | 426 cm-1 | ||
| νTO(A1) | 514 cm-1 | ||
| νTO(E1) | 614 cm-1 | ||
| νLO(A1) | 663 cm-1 | ||
| νLO(E1) | 821 cm-1 | ||
| νLO(E1) | 821 cm-1 | ||
| nTO (E1) | 657-673 cm-1 | Collins et al. (1967); Collins et al. (1967); MacMillan et al. (1993); Perlin et al. (1993); Meng (1994) |
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| nTO (A1) | 607-614 cm-1 or 659-667 cm-1 |
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| nLO (E1) | 895-924 cm-1 | ||
| nLO (A1) | 888-910 cm-1 | ||
| n(1) (E2) | 241-252 cm-1 | ||
| n(2) (E2) | 655-660 cm-1 |
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AlN, Wurtzite. Pressure dependences
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