AlN - Inllium Nitride

Mechanical Properties, Elastic Constants, Lattice Vibrations

Basic Parameters
Elastic 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
   
    {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)
   
    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 structure

Phonon 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)
nTO (A1) 607-614 cm-1
  or 659-667 cm-1
   
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    
AlN, Wurtzite. Pressure dependences  of the phonon frequencies.
Perlin et al. (1993)
AlN. Calculated phonon dispersion curves and phonon DOS function for bulk AlN.
The solid and dashed lines correspond to the Λ1 (or T1) and Λ2 (or T2) irreps, respectively.
Davydov et al. (1998)