Nano-architected GaN spinodoid metamaterials with tailorable anisotropic piezoelectric properties

) compared to bulk GaN. These enhancements in piezoelectric performance are strongly affected by their underlying nano-architecture, which is governed by the evolutionary time during spinodal decomposition. Due to the asymmetric topology designs, GaN spinodoid metamaterials can possess more independent non-zero piezoelectric stress/strain constants as well as elastic constants compared to the bulk piezoelectric GaN. Relative density is found to further modulate the piezoelectric properties and anisotropy of the nano-architected piezoelectric materials through the contribution of surface effects and tuning the surface-to-volume ratio. This work underscores the potential of topology engineering to overcome crystallographic constraints in piezoelectric nanomaterials, opening avenues for their applications in nano-energy harvesters and three-dimensional pressure mapping/sensing nano-devices.