Microstructure and ferroelectric properties of sol-gel derived Bi3.15Nd0.85Ti3O12 thin films on Pt∕Ti∕SiO2∕Si(100)

${\mathrm{Bi}}_{3.15}{\mathrm{Nd}}_{0.85}{\mathrm{Ti}}_3{\mathrm{O}}_{12}$ (BNdT) thin films were deposited on $\mathrm{Pt}∕\mathrm{Ti}∕{\mathrm{SiO}}_2∕\mathrm{Si}$ substrates using a sol-gel process. The film annealed at $750°\mathrm{C}$ is composed of grains of $50–100\mathrm{nm}$ in diameter. The fine grains show nearly random orientations. “Micropores” were frequently observed at the junctions of the grains and they are mostly amorphous, while sometimes containing very fine crystalline particles with sizes of only a few nanometers. The BNdT film capacitors with a $\mathrm{Pt}$ top electrode showed excellent ferroelectric properties. The remanent polarization and the coercive field were in the range of $41–43\mu \mathrm{C}∕{\mathrm{cm}}^2$ and $70–84\mathrm{kV}∕\mathrm{cm}$ , respectively. The BNdT capacitors did not show any significant fatigue up to $5\times {10}^9$ switching cycles at a frequency of $1\mathrm{MHz}$ .