In the present work, donor (Nb5+)-doped, acceptor (Fe3+)-doped, and undoped PZT ceramics were achieved by sintering nano- and micron-sized powders. The bulk density, grain size, remanent polarization, dielectric constant, dielectric loss, and Vickers hardness of the prepared components were measured. With the experimental results obtained, the effects of doping additives and grain size on the ferroelectric and mechanical properties of the materials investigated were analyzed and discussed. It was noted that donor-doped materials had higher remanent polarization and dielectric constant and acceptor-doped materials had lower dielectric loss and higher hardness. Fine-grained materials were found to have lower dielectric loss and higher hardness.