Effects of lattice parameters on piezoelectric constants in wurtzite materials: A theoretical study using first-principles and statistical-learning methods

This is the authors' abstract. We don't add key points for this paper.

Longitudinal piezoelectric constant ( e 33 ) values of wurtzite materials, which are listed in a structure database, are calculated and analyzed by using first-principles and statistical learning methods. It is theoretically shown that wurtzite materials with high e 33 generally have small lattice constant ratios ( c / a ) almost independent of constituent elements, and approximately expressed as e 33 ∝ c / a − ( c / a ) 0 with ideal lattice constant ratio ( c / a ) 0 . This relation also holds for highly-piezoelectric ternary materials such as Sc x Al 1− x N. We conducted a search for high-piezoelectric wurtzite materials by identifying materials with smaller c / a values. It is proposed that the piezoelectricity of ZnO can be significantly enhanced by substitutions of Zn with Ca.