Effects of the Deposition Parameters on the Structural Properties of Highly Anisotropic Bi_4-x Nd _x Ti₃O₁₂ Films Synthesized by using Pulsed Laser Deposition

In this study, Bi_4−xNd_xTi₃O₁₂ (BNdT), in which neodymium is substituted into Bi₄Ti₃O12 (BiT) with a bismuth layer-structured ferroelectrics (BLSFs) structure, was deposited on a Pt/Ti/SiO₂/Si substrate by using pulsed laser deposition (PLD). The BNdT film is known to exhibit structural and electrical anisotropy with the reported maximum spontaneous polarization (P_s) along the a axis (∼55 μC/cm²)and the c axis (−5 μC/cm²). The ability of BNdT to control the structural change with growth orientation is key to its enhanced properties. In a PLD system, a few important factors, such as deposition temperature, oxygen pressure, and energy fluence, are responsible for the structural variation. We aimed to enhance the structural properties of polycrystalline BNdT film, so we investigated the change in the orientation of BNdT film according to PLD deposition conditions. To identify the mechanism of structural change according to deposition conditions, we used X-ray diffraction to analyze the film’s orientation and to calculate the lattice constants and the crystallite size. We also used field emission scanning electron microscopy (FE-SEM) to assess the surface morphology and the grain shape of the BNdT films.