Fabrication and Characterization of BiFeO₃-BaTiO₃Ceramics by Solid State Reaction

Structural, spectroscopic, and dielectric characterizations of Mn-doped 0.67BiFeO3-0.33BaTiO3 multiferroic ceramics

“…For example, in the BiFeO 3 -BaTiO 3 solid solution system, anomalous dielectric and magnetic behaviors were observed at concentration of 33 mol% of BaTiO 3 , which was closely related to the structural transformation between the rhombohedral and cubic phases. The composition of 0.67BiFeO 3 -0.33BaTiO 3 solid solution exhibited the spontaneous polarizations of 35 C/cm 2 at room temperature [8]. Although the perovskite structure of these ceramics has been found to be stable and the spontaneous magnetic moment is increased at room temperature, the insulation resistance of BiFeO 3 -ABO 3 ceramics has not been improved sufficiently and their ferromagnetism is still weak.…”

“…It is noticed that all the dielectric constants and dielectric losses are decreased as increasing the frequency up to 10 5 Hz, and then remain almost constant in the frequency range of 10 5 -10 6 Hz. The fast decrease of the dielectric constants in the low frequency region (below 10 5 Hz), can be attributed to the space charge polarization induced by oxygen vacancies in the perovskite Mn-doped 0.67BiFeO 3 -0.33BaTiO 3 ceramics [4,8,9]. The dielectric constants of Mn-doped 0.67BiFeO 3 -0.33BaTiO 3 ceramics measured at 10 4 Hz, 10…”

“…Although the perovskite structure of these ceramics has been found to be stable and the spontaneous magnetic moment is increased at room temperature, the insulation resistance of BiFeO 3 -ABO 3 ceramics has not been improved sufficiently and their ferromagnetism is still weak. Previous investigations on the ferroelectric and ferromagnetic properties of BiFeO 3 -BaTiO 3 solid solution have demonstrated that their dielectric properties were complicated by high dielectric losses and high conductivity, which were ascribed to the valence fluctuation of Fe and the formation of oxygen vacancies [4,8]. Recently, it has been reported that Mn-doping can significantly reduce the leakage current and dielectric losses of the BiFeO 3 -BaTiO 3 solid solution [11,12].…”

“…To solve these problems, some attempts have been made including small dopants (e.g., lanthanides such as La, Ce, Eu) at the Bi/Fe sites to improve the dielectric properties of BiFeO 3 [5,6]. There are also several reports on the synthesis of solid solution of BiFeO 3 with other ABO 3 perovskite materials such as BaTiO 3 [4,[7][8][9] and PbTiO 3 [10] to stabilize the perovskite structure and enhance the electrical insulating properties of BiFeO 3 . For example, in the BiFeO 3 -BaTiO 3 solid solution system, anomalous dielectric and magnetic behaviors were observed at concentration of 33 mol% of BaTiO 3 , which was closely related to the structural transformation between the rhombohedral and cubic phases.…”

Synthesis and properties of perovskite BiFeO3-K0.5Na0.5NbO3 ceramics by solid-state reaction

“…This result suggests that doped Mn effectively prevents the influence of valence fluctuation of Fe ions in BiFeO 3 K 0.5 Na 0.5 NbO 3 , as in the case for BiFeO 3 BaTiO 3 ceramics. 8) Since dielectric properties are improved by Mn doping, perovskite single-phase ceramic samples having near 0.9BiFeO 3 0.1K 0.5 Na 0.5 NbO 3 composition were additionally synthesized. Figure 4 shows the XRD patterns of Mn-doped (1 ¹ x)BiFeO 3 xK 0.5 Na 0.5 NbO 3 (x = 0.06, 0.08, 0.12) ceramics.…”