Résumé
This article is devoted to the thermal expansion of ZnSb combining experiments (neutron and X-ray) andcalculations based on density functional theory. Related properties are also studied such as: the zone-center(Raman and infrared) phonon modes, the dielectric (electronic and static) tensors, the phonondensity-of-states, the specific heats and the isotropic atomic displacement parameters. Our experimentaldata show highly anisotropic thermal expansion with large values along the a-direction. Concomitantly,a large increase of the Zn–Zn intra-ring distances and of one of the intra-ring Zn–Sb distances isobserved, while other interatomic distances do not significantly change. In agreement with ourcalculations, the thermal expansion has positive values along the three crystal directions except around30 K where it has weak negative values along the b and c-directions. This anomalous expansion is moreimportant along the c-direction and it is mainly due to phonon modes with frequencies up to 75 cm1.These modes are located in the S–Y–G (resp. G–Z) q-point range along the b (resp. c) direction. Phononmodes located in the G–X and in the Y–G–Z q-point range with frequencies up to 175 cm1 areresponsible for the positive large thermal expansion at room temperature along the a-direction. Themuch reduced anisotropy of the thermal conductivity is related to the lower Debye temperatures alongthe b and c-directions and mainly to the small transverse sound velocity between these directions.