Dielectric spectroscopy and ferroelectric properties of magnesium modified bismuth titanate ceramics

Mg doped bismuth titanate ceramics Bi4Ti3-xMgxO12 (x = 0.2, 0.4, 0.6) (BMgT) synthesized using a solution combustion technique are studied in this paper. This work examines the effect of Mg doping at B site of bismuth titanate on its crystalline structure, ferroelectric properties and electrical conduction characteristics over a broad temperature range. Addition of Mg2+ does affect the lattice symmetry of bismuth titanate by causing shrinkage in the unit cell. An increase in the dielectric constant and decrease in loss tangent is observed due to increase in magnesium content. The Nyquist plots are interpreted using a RC model which explains the contribution of the grain-bulk and the grain boundary resistivities to the total resistivity of the materials. The P-E loops are observed to become lossier with an increase in magnesium content due to increase in leakage current as a result of lattice distortion introduced in the unit cell.