Dielectric and Magnetic Properties of Ba(Fe1/2Ta1/2)O3-BiFeO3 Ceramics

The properties of (1-x)Ba(Fe1/2Ta1/2)O-3-xBiFeO(3) [(1-x)BFT-xBFO] (x = 0.0, 0.1, 0.3, 0.5) ceramics have been investigated. (1-x)BFT-xBFO powders were synthesized by a modified two-step calcination technique, and ceramics were fabricated by a conventional technique. X-ray diffraction (XRD) analysis revealed that the modified ceramics exhibited a mixture of BFT cubic phase and BFO rhombohedral phase. The peaks shift increased with increasing BFO content to a maximum value for the composition with x = 0.5. The overall shift of the XRD patterns indicated distortion of the unit cell, which may be due to ions from BFO entering the BFT lattice. BFO additive promoted grain growth, while the maximum density of the studied ceramics was observed for the x = 0.1 composition. The modified ceramics presented enhanced thermal and frequency stability of the dielectric constant. BFO additive also reduced the loss tangent for the system. Improvement of the magnetic behavior was observed after adding BFO. Furthermore, all the ceramics, including pure BFT (a nonmagnetic phase at room temperature), presented a magnetocapacitance effect, which can be related to magnetoresistance along with Maxwell-Wagner polarization effects.