Robust insulating La and Ti co-doped BiFeO3 multiferroic ceramics

Abstract

Low resistivity and high dielectric loss are two major problems associated with the fabrications of BiFeO3 multiferroic ceramics. Adapting co-doping on the A- and B-sites, robust insulating Bi0.98La0.02Fe0.99Ti0.01O3 ceramics with resistivity ~1011 Ω m measured applying electric field 90 kV/cm and dielectric loss tanδ below 0.02 over frequency range of 100 Hz–2 MHz were prepared using a refined solid state reaction electroceramic processing. Intentional La/Ti co-substitution was experimentally illustrated to form ternary solid solution, which enhances thermodynamic stability of BiFeO3 perovskite phase, allowing obtain high resistive low dielectric loss bismuth ferrite ceramics. Meanwhile, passive unknown impure ions from Bi2O3 and TiO2 raw oxides were also found combining synergetic effect available to obtain low dielectric loss ceramics. In contrast to the traditional method introducing vacancies via doping heterovalent ions, various kinds of vacancies were introduced in advance into the ceramic samples through controlling chemical stoichiometry via employing impure raw materials, and they are experimentally demonstrated responsible for dielectric loss relaxation behaviors and high dielectric loss observed in the Bi0.98La0.02Fe0.99Ti0.01O3 ceramics.