The structural evolution and multiferroic properties of nonstoichiometric BiFe_(1-4x/3)Zr_xO_3 ceramics with Fe vacancies

摘要

Nonstoichiometric BiFe_(1-4x/3)Zt_xO_3 (0 ≤ x ≤ 15%) multiferroic ceramics with Fe vacancies were synthesized by using rapid liquid phase sintering process. It was found that nonstoichiometric Zr substitution induced structure distortion, and an appropriate amount of Zr could remove impurity phases. XPS and PAS studies indicated that there was no obvious change in Bi vacancies concentration, but the Fe vacancies concentration increased with increasing substitution amount of Zr. The Fe~(2+) concentration first decreased and then increased with the increase in substitution amount of Zr, while the oxygen vacancies concentration decreased with increasing substitution amount of Zr. Nonstoichiometric Zr substitution could effectively enhance the multiferroic behaviors of BiFeO_3. The evolution of structure and properties induced by nonstoichiometric Zr substitution indicated that Fe~(2+) concentration was the main source of the leakage current, while Fe vacancies concentration was a key factor that modulated the magnetic performances of BiFeO_3. Furthermore, the applied magnetic field dependence of dielectric constant suggested that the magnetodielectric effect increased with increasing Zr substitution amount. The results above imply that nonstoichiometric BiFeO_3 composition with Fe vacancies has great potential for exploiting high quality BiFeO_3-based ceramics.