Synthesis and properties of Nd-substituted bismuth titanate polycrystalline thin films with polar-axis orientation

To gain a deep insight into the contribution of Nd-substitution, we have investigated structural phase transition behavior in Bi_4-xNd _xTi₃O₁₂ (BNT) powders derived from chemical solutions. Differential thermal analysis and thermo-gravimetry (DTA-TG) and X-ray diffraction (XRD) studies indicated that the para- and ferroelectric transition temperature (Curie temperature, T_c) continuously decreased with increasing x. The XRD studies also showed that continuous decrease in lattice anisotropy (a/b, orthorhombicity) with the increase of x. Considering the close relationship with T_c, a/b and spontaneous polarization P_s in displacive ferroelectrics, Nd-substitution may not enhance the intrinsic P_s in Bi₄Ti₃O₁₂ (BIT). For direct evaluation of P_s upon Nd-substitution, synthesis route to polar-axis-orientated BNT films was investigated.