Dielectric response and structural features of Pb(Sc1/2Ta1/2)O-3 (PST) sol-gel derived thin films

Relaxor Pb(Sc-12/Ta-1/2)O-3 (PST) thin films have been prepared using mixed alkoxide and acetate precursors on TiO2/Pt/TiO2/SiO2/Si substrates. Relaxor behavior as evidenced by frequency dispersion of the permittivity as a function of temperature was observed, as well as a thickness dependence of the dielectric constant. The highest values of dielectric constant were observed for the thicker 650 nm samples displaying a room temperature dielectric constant near 2000, with a loss tangent of 0.3% at 1 kHz. The AC and DC field dependence of dielectric properties showed different signs of non-linearity, which is qualitatively explained in terms of polar region boundary movement. In addition, the measurement and analysis of pyroelectric properties under DC bias suggests the presence of polar regions in the ostensibly cubic paraelectric phase at 25degreesC.