On the dielectric and ferroelectric properties of Ba _0.75Sr _0.25TiO ₃ thin films deposited by RF Sputtering

The ferroelectric behavior of Ba _0.75Sr _0.25TiO ₃ (BST) thin films deposited on nichrome substrates by RF-Sputtering sintered in situ at 673-1023 K temperature range has been studied. The thin films microstructures were observed using atomic force microscopy to determine rugosity and grain size. Extensive grain growth was observed at temperatures of 822 and 1023 K, varying from 75 to 95 nm, respectively. The ferroelectric properties were determined by the hysteresis loops applying an electric field of 100 kV/cm. The films sintered in the temperature range of 822-1023 K show a reduction of the remnant polarization Pr from 9.87 °C/cm ² to 2.23 °C/cm ², and the coercive field strength E _c decrease from 57.75 kV/cm ² to 19.85 kV/cm ². In situ heat treatments let to have more uniform grain size distribution, and relative low rugosities.