A large d33 of ∼415 pC/N for (1−x)(K0.40Na0.60)(Nb0.96Sb0.04)NbO3-x(Bi0.5Na0.5)0.9Cu0.1ZrO3 ceramics. R-O&O-T multiphase coexistence developed by controlling BNZC contents. Strain∼0.21% and d33∗∼538 pm/V for x = 0.04. Illuminating physical origin for the enhanced electrical properties.