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short communications
Precise lattice strains measured using high-resolution neutron diffraction from a solid polycrystalline sample are used to explore the single-crystal elastic constants of α-Al2O3 (corundum). The analysis confirms a recent suggestion that, contrary to the long-accepted view, the sign of s14 should be negative. It also indicates that the magnitude of s13 should be adjusted from −0.38 × 10−12 to −0.47 × 10−12 Pa−1. It is found that, micromechanically, the polycrystal responds to stress in a manner very close to the Reuss limit. The results confirm the applicability of the diffraction method, which could prove useful when other techniques give ambiguous results.