Low-temperature fabrication of pyroelectric Ba_0.8Sr_0.2TiO₃ thin films by a sol-gel process

Ba_0.8Sr_0.2TiO₃ films were fabricated with a 0.05 M solution by a sol-gel process at temperatures between 550 and 650 °C. Analysis by x-ray diffraction, Raman spectroscopy, and scanning electron microscopy revealed that the films annealed at 650 °C showed pure perovskite phase, tetragonal structure, and columnar grains with an average grain size of 150 nm. Electrical measurements performed on the films annealed at 650 °C showed two dielectric peaks in the dielectric constant-temperature curve, a remnant polarization of 1.4 μC/cm², a coercive field of 18.3 kV/cm, and good insulating property. The measured pyroelectric coefficient for the films annealed at 650 °C was larger than 3.1 × 10^-4 C/m²K at the temperatures ranging from 10 to 26 °C and reached the maximum value of 4.1 × 10^-4 C/m²K at 16 °C. The excellent pyroelectric property rendered the Ba_0.8Sr_0.2TiO₃ films annealed at 650 °C promising for uncooled infrared detectors and thermal imaging applications.