Mechanical and Thermophysical Properties of Cubic Rock-Salt
AlN Under High Pressure
and ABDELHAKIM LATRECHE
lectronique et Composants, Faculte
des Sciences, Universite
tif, Algeria. 2.—Faculte
des Sciences et de la Technologie, Universite
El Ibrahimi de Bordj Bou Arreridj, 34000 Bordj Bou Arreridj, Algeria. 3.—Laboratoire Mate
mes Electroniques (LMSE), Universite
Mohamed Elbachir El Ibrahimi de Bordj Bou
Arreridj, 34000 Bordj Bou Arreridj, Algeria. 4.—School of Mathematics and Physics, Lanzhou
Jiaotong University, Lanzhou 730070, People’s Republic of China. 5.—e-mail:
Density functional theory, density functional perturbation theory, and the
Debye model have been used to investigate the structural, elastic, sound
velocity, and thermodynamic properties of AlN with cubic rock-salt structure
under high pressure, yielding the equilibrium structural parameters, equation
of state, and elastic constants of this interesting material. The isotropic shear
modulus, Pugh ratio, and Poisson’s ratio were also investigated carefully. In
addition, the longitudinal, transverse, and average elastic wave velocities,
phonon contribution to the thermal conductivity, and interesting thermody-
namic properties were predicted and analyzed in detail. The results demon-
strate that the behavior of the elastic wave velocities under increasing
hydrostatic pressure explains the hardening of the corresponding phonons.
Based on the elastic stability criteria under pressure, it is found that AlN with
cubic rock-salt structure is mechanically stable, even at pressures up to
100 GPa. Analysis of the Pugh ratio and Poisson’s ratio revealed that AlN with
cubic rock-salt structure behaves in brittle manner.
Key words: AlN, elastic constants, sound velocity, thermodynamic
Aluminum nitride (AlN) is an important coordi-
nated III–V compound, in general having partially
ionic and partially covalent chemical bonds.
exhibits several remarkable physical properties,
such as high thermal conductivity, high melting
point, and large bulk modulus.
conditions, AlN crystallizes in wurtzite (B4) struc-
Under increasing pressure, x-ray diffraction
study indicates that the B4 phase transforms to
cubic rock-salt (B1) phase at around 14 GPa.
past as well as recently, other researchers have also
studied several other interesting physical properties
of AlN compound.
AlN material also occurs as two other poly-
morphs, i.e., cubic zincblende (B3, ZnS type)
rock-salt (B1, NaCl type) structures.
structure of AlN can be obtained under normal
conditions using two approaches. The ﬁrst is to
quench the B4 structure from 16.5 GPa and 1400°C
The second one is to depressurization of
B4 phase from high to ambient pressure.
ambient conditions, the lattice parameter of AlN
nanowires with NaCl-type structure was found to be
a = 4.064 A
larger than the value of 4.045 A
polycrystalline AlN with NaCl lattice structure.
We report herein a more detailed discussion on
the structural, mechanical, and thermodynamic
properties of AlN with rock-salt structure. The
(Received February 13, 2017; accepted February 22, 2018;
published online March 9, 2018)
Journal of ELECTRONIC MATERIALS, Vol. 47, No. 7, 2018
2018 The Minerals, Metals & Materials Society