Investigation of structural, electrical, and dielectric properties of lead-free (BiFeO 3 ) (1- x ) – (CaTiO 3 ) x ceramics

This paper investigates the influences of CaTiO 3 (CTO) on the structural phase stability, dielectric properties and leakage current density of the polycrystalline BiFeO 3 (BFO) ceramics. The composite (BFO) (1- x ) –(CTO) x ( x = 0.6, 0.7, and 0.8) ceramics with sintered density ≥ 95% were successfully prepared by a direct mixing of the calcined powders of BFO and CTO in the stoichiometric ratio followed by microwave sintering in the temperature range of 1100–1280 °C, although there is nearly 500 °C difference in the sintering temperatures of BFO (~ 850–900 °C) and CTO (~ 1350 °C) ceramics. In the composite BFO–CTO ceramics, the crystal structure is dominated by the CTO phase with Pbnm orthorhombic symmetry in comparison to the BFO-based R3c rhombohedral symmetry. The average grain size in the sintered samples of the BFO–CTO ceramics has been decreased by an order of magnitude in comparison to pure BFO. The leakage current density has been reduced by four orders of magnitude in the sintered BFO–CTO samples, 1.9 × 10 –1 A cm −2 for x = 0 to 7.4 × 10 –5 cm −2 for x = 0.8, measured at an electric field of 1 kVcm −1 . The increase of CTO content in the BFO matrix resulted in an enhancement of dielectric constant and reduction of loss tangent (tan δ ). The influences of CTO on the structural, microstructural, electrical and dielectric properties of BFO have been discussed in details in this work.