STUDY OF BiFeO3 INCORPORATION IN STRUCTURAL, DIELECTRIC AND FERROELECTRIC PROPERTIES OF BaTiO3 CERAMICS

Abstract

Perovskite BaTiO3 was prepared by the solid state reaction method with the materials BaCO3 and TiO2. The calcinations were carried out at 11500C for 4 hrs. To study the structural, dielectric and ferroelectric properties of BaTiO3 ceramics, the sintering was carried out at 1100°C, 12000C and 13000C for 4 hrs respectively. The XRD analysis shows the single phase tetragonal perovskite of BaTiO3 ceramics without any second phase. The average grain size increased from 0.20prn to 0.70irn on increasing the sintering temperature. The dielectric properties i.e., dielectric constant 'Cr' and dielectric loss 'tan6' are investigated and found to be large Er and low b. loss; the ferroelectric properties (i.e., remnant polarization and the coercive field) were also investigated and found to be large polarization. A single-phase multiferroic ceramics of (I - x) BiFe03 - x BaTiO3 (BFO - x BTO) were also prepared by the solid state reaction method with wide range of the material composition (x = 0. 1 - 1.0). This BFO with BTO shows structural transformations over the entire compositional range. These transformations were confirmed by the X-ray diffractions (XRD). Below x=0.3 BFO shows rhombohedral structure, above this composition it shows cubic structure and above 90% of BTO the structure becomes tetragonal. The ferroelectric Curie temperature Tc decreases with increasing of BTO concentration, which shows small relaxation. Average grain size first increases and then decreases that is found large for 0.5 BF- 0.5 BT composite. The dielectric constant enhances as BTO content increases. The polarization first increases and becomes maximum for x=0.3, after that it starts decrease with the increasing of the BTO concentration. This suggested that the morphotropic phase boundary (MPB) exist at this composition that means the rhombohedral and cubic phases coexist for 0.7BF - 0.3BT composite.