Elastic Constants of GaS and GaSe Layered Crystals Determined by Brillouin Scattering

The five independent elastic constants of GaS and GaSe have been precisely determined at room temperature from high-resolution Brillouin spectra in various scattering geometries. The results are: c 11 =12.16, c 12 =3.52, c 13 =1.14, c 33 =3.79, c 44 =0.95, \(c₆₆{=}1/2(c₁₁-c₁₂){=}4.30\) for GaS, and c 11 =10.50, c 12 =2.97, c 13 =1.22, c 33 =3.51, c 44 =1.00, \(c₆₆{=}1/2(c₁₁-c₁₂){=}3.77\) for GaSe, in units of 10 10 Nm -2 . We found a relatively low elastic anisotropy, associating with the layered structure of GaS and GaSe crystals.