In the present study, Na$_{0.329}$Bi$_{0.329}$Ba$_{0.042}$Sr$_{0.30}$TiO$_3$ (NBBST) and its solid solutions with Nd(Mg$_{0.5}$Ti$_{0.5}$)O$_3$ (NMT), Nd(Mg$_{2/3}$Nb$_{1/3}$)O$_3$ (NMN), and Nd(Zn$_{2/3}$Nb$_{1/3}$)O$_3$ (NZN) were synthesized and investigated. The phase composition, microstructure, dielectric properties, and impedance characteristics were analyzed for their optimized dense sintered forms. X-ray diffraction (XRD) confirmed the formation of a single-phase perovskite structure in all compositions within the detection limit. All ceramics exhibited dense microstructures; however, the doped samples showed a reduced average grain size compared to pure NBBST. Among the composition... More >