Excellent piezoelectric properties of (K, Na)(Nb, Sb)O3-CaZrO3-(Bi, Ag)ZrO3 lead-free piezoceramics

•The KNNS-0.01CZ-0.03BAZ piezoceramic has an ideal R-O-T multi-structure.•This piezoceramic exhibits nanodomains (3 nm × 20 nm) and relaxor properties.•Large d33 value of 680 ± 10 pC/N was observed from this piezoceramic.•High d33 is explained by the existence of the R-O-T multi-structure and nanodomains.