Using first-principles calculations, we investigate piezoelectricity in a wide range of binary wurtzite semiconductors. We find that piezoelectricity is intimately related to the bond character, e.g. the negative longitudinal piezoelectric effect (NLPE) tends to occur in covalent compounds. We further find a universal sign rule (negative clamped-ion term and positive internal-strain term) for piezoelectricity, and the NLPE occurs as a result of the domination of the former over the latter. Moreover, there exists an inverse linear correlation between the longitudinal and transverse piezoelectric coefficients. This work may offer a simple criterion for efficient computational screening of materials exhibiting the NLPE.

Hexagonal ABC semiconductors with a polar structure are potential candidates for piezoelectric applications. The intriguing negative longitudinal piezoelectric effect (NLPE) and electric auxetic effect (EAE) may exist in these materials,...