The performance of the A-site donor/B-site acceptor-cosubstituted (K, Bi) Bi4(Ti3.8M0.2)O15 ferroelectric thin films with , and Ni

A-site donor/B-site acceptor-cosubstituted (K0.45Bi0.55)Bi4(Ti3.8M0.2)O15 ferroelectric thin films with M=Mn,Fe, and Ni were fabricated by chemical solution deposition and annealed at 600 ∘C for 30 min. Without incorporating lanthanides, the films displayed improved ferroelectricity when the cosubstitution of donor and acceptor formed the additional dipoles without the Ti4+–Ti3+ polaron and oxygen vacancies. The conduction mechanisms of the leakage current involved a field-assisted ionic conduction related to the polaron and a space charge limited conduction related to oxygen vacancies. Non-lanthanide KBTi–Mn and KBTi–Fe thin films displayed an improved ferroelectricity with high remanent polarization of 39 and 34 μC/cm2, respectively.