Ferroelectricity in sol-gel derived Ba0.8Sr0.2TiO3 thin films using a highly diluted precursor solution

Barium strontium titanate films with good ferroelectricity have been obtained by a developed sol-gel processing, using a highly dilute spin-on solution. X-ray diffraction and scanning electron microscopy investigations show that large grains with the size of 100-200 nm in the films are formed from highly dilute spin-on solutions with layer-by-layer homoepitaxy. Polarization-electric field and dielectric constant-temperature (epsilon(r)-T) measurements reveal that the ferroelectricity becomes more evident as the grain size increases. The measurements for quality Ba0.8Sr0.2TiO3 ferroelectric films derived from a 0.05 M solution have shown a remnant polarization of 3.5 mu C/cm(2), a coercive field of 86 kV/cm, and two distinctive phase transitions. (C) 1999 American Institute of Physics. [S0003- 6951(99)05240-7].