Enhanced Piezoelectric Response of AlN via CrN Alloying

Currently, at the basis of all piezoelectric applications are just a handful of materials. Among these AlN is important, even though its piezoelectric response is not particularly large. To enhance the response of wurtzite AlN, we could alloy it with a rocksalt nitride, and density functional theory indicates that the piezoelectricity of (Cr,Al)N is very sensitive to composition. Experiments show that the wurtzite-to-rocksalt transition occurs at 30% Cr, where the alloy's response is about four times that of pure AlN. This viable, tunable system offers significant improvements in piezoelectric applications, such as resonators and acoustic-wave generators.