M.B Kanoun A.E Merad G Merad J Cibert H Aourag 2004 Prediction study of elastic properties under pressure effect for zincblende BN AlN GaN and InN Solid-State Electronics vol. 48 no. 9 pp. 1601-1606
[] also employs full-potential linearized augmentedplane wave method (FP-LAPW) method
The elastic constants are obtained by calculating the total energy versus volume conserving strains using the Charpin model. From the elastic parameter, it is inferred that these compounds are elastically stable and brittle in nature.
constants are important in providing valuable information about the stability and stiffness of materials. In order to calculate them
we have used numerical first-principle calculations by computing the components of the stress tensor for small strains, using the
method developed by Charpin and integrated in WIEN2K code.
The computed values of the elastic constants for AB compounds are given in Table 2. To the best of our knowledge no experimental
value for the elastic constants of the AB compounds have been published, while only theoretical calculations on ScN, YB and LaSb
compounds have been performed.
can notice that the unidirectional elastic constant C 11 ,which is related to the unidirectional compression along the prin-
cipal crystallographic directions is much higher than C 44 , indicating that these compounds present a weaker resistance to the pure
shear deformation compared to the resistance to the unidirectional compression. The requirement of mechanical stability in a cubic
structure leads to the following restrictions on the elastic constants [45]: 13 ðC 11 þ 2C 12 Þ > 0 ; C 44 > 0 ; 12 ðC 11 À C 12 Þ > 0 ; C 12 < B <
C 11 . These criteria are satisfied, indicating that these compounds are elastically stable except ScSb and ScBi.
The crystal elastic anisotropy has an important implication in engineering science since it is vastly correlated with the possibility
to induce microcracks in materials [46]. To quantify this, we have computed the anisotropy factor A 0 1⁄4 2C 44 =ðC 11 À C 12 Þ from the
present values of the elastic constants. For isotropic material, A 0 is equal to 1, while any value smaller or larger than 1 indicates
anisotropy. The magnitude of the deviation from 1 is a measure of the degree of elastic anisotropy possessed by the crystal. From
the computed anisotropy values listed in Table 2, it is clear that the anisotropy factor value for all compounds deviates from unity,
meaning that they are characterized by a profound anisotropy. Our results are in fairly good agreement with those previously obtained
M. Shoaib, G. Murtaza, R. Khenata, M. Farooq, Roshan Ali, 2013, Structural, elastic, electronic and chemical bonding properties of AB (A=Sc,Y,La;B=N,P,As,Sb,Bi) from first principles, Computational Materials Science, vol. 79, pp. 239-246