Sol–gel preparation and characterization of calcium modified lead titanate (PCT) thin films

Abstract

Thin ferroelectric films of calcium modified lead titanate Pb 1− x Ca x TiO 3 where x=0.28 (72:28) (PCT) are prepared by sol–gel spin coating process on ITO coated corning glass 7059 substrates. Sol–gel technology offers attractive features such as low processing temperature and ease of tailoring of the structural and electrical properties by controlling the composition of the films. Films are prepared using lead acetate trihydrate, calcium acetate hydrate and titanium isopropoxide as precursors, along with 2-methoxy ethanol as solvent and acetic acid as catalyst. Characterization of these films by X-ray diffraction show that the films exhibit tetragonal structure with perovskite phase. Replacement of calcium at Pb site in lead titanate results in reduction of tetragonal ratio ( c/ a), thus resulting in better electrical and ferroelectric properties. Atomic force microscope (AFM) images are characterized by slight surface roughness with a uniform crack free, densely packed structure. Dielectric, pyroelectric and ferroelectric studies carried out on these films have been reported and discussed. PCT shows fairly high voltage responsivity and appreciable detectivity. Moreover, its high value of remanent polarization (∼28 μC/cm 2) along with small value of coercive field (∼110 kV/cm) makes it a better suited material for non-volatile memory applications.