Effect of trivalent ions (La3+, Nd3+) on the properties of Bi4Ti3O12 single crystals

Growth of trivalent ions (La3+ and Nd3+) doped Bi4Ti3O12 (BIT) single crystal by self-flux method using excess Bi2O3 as flux is reported. The effects of trivalent ions on the structural, thermal, optical and ferroelectric properties of BIT crystal were investigated. The results of X-ray diffraction and thermal analysis, respectively, indicate that the lattice distortion, liquidus/crystallization temperatures of BIT considerably increase with La and Nd concentrations. Substitution of La in Bi3+ shifts the lower absorption edge towards the ultra-violet region (∼20–25 nm), while no shift is observed for the BIT:Nd crystal. Regardless of the dopants, the optical microscopy patterns of the crystal surfaces reveal the existence of 90° domains. Dielectric measurements indicate that BIT:Nd crystals exhibit no significant variation in Curie temperature (TC) of BIT. Substitution of La and Nd in BIT increase both the remnant polarization (Pr) and coercive field (Ec) of BIT crystals.