B-site acceptor doped AgNbO3 lead-free antiferroelectric ceramics: The role of dopant on microstructure and breakdown strength

B-site aliovalent modification of AgNbO₃ with a nominal composition of Ag(Nb_1-xM_x)O_3-x/2 (x = 0.01, M = Ti, Zr and Hf) was prepared. The effects of dopants on microstructure, dielectric, ferroelectric and conduction properties were investigated. The results indicate that the introduction of acceptor dopant does not lead to grain coarsening. Zr⁴⁺ and Hf⁴⁺ doping are beneficial to stabilize the antiferroelectric phase of AgNbO₃. Among all the samples, Ti⁴⁺ doped AgNbO₃ has the minimum resistivity while Hf⁴⁺ doped AgNbO₃ has the maximum resistivity, therefore, Hf⁴⁺ doped AgNbO₃ has high BDS. The XPS results indicate that the conduction behaviour is associated with the concentration of oxygen vacancies. This work hints that acceptor dopant is also effective on the microstructure control and chemical modification of AgNbO₃-based ceramics.