Site engineering in chemical-solution-deposited Bi3.25La0.75Ti3O12 thin films using Ce,Zr, Mn and Si atoms

Ferroelectric Bi_3.25La_0.75Ti₃O₁₂ (BLT) thin films were fabricated by depositing sol-gel solutions on Pt(111)/Ti/SiO₂/Si (100) substrates. Crystallographic orientations of the BLT films were random, but the preferred orientations along (00l) and (117) axes were found. All films showed a single-phase bismuth-layered structure but the orientation in the films could be engineered by optimizing the growth condition, as well as by introducing dopant atoms such as Ce and Zr in the films, which in turn influenced the ferroelectric properties of the films significantly. The shape of c-axis-oriented grains was more plate-like, while that of (117)-oriented grains was rod-like. Small % substitution of Ce, Mn, and Zr atoms at Ti site enhanced the remanent polarization by approximately 20%, while substitution of Si atoms reduced the remanent polarization in BLT films but improved insulating properties. It was also demonstrated that fatigue endurance could be controlled by the concentration of dopant atoms, which was thought to be due to the decrease in oxygen vacancy concentration.