PLZT-based multilayer composite thin films, part I: Experimental investigation of composite film structures

Composite thin films produced by depositing alternating layers of various PLZT compositions were fabricated on Pt-coated Si wafer and Ag foil substrates. Films were prepared by MOD processes including automatic spin and dip coating from acetate precursors followed by annealing at 700°C. Ferroelectric (FE)/antiferroelectric (AFE), FE/relaxor and relaxor/AFE composites consisted of individual layer compositions including ferroelectric PLZT 2/55/45 and 7/65/35; AFE PLZT 0/100/0, 0/96/4 and 0/95/5; relaxor PLZT 9.5/65/35 and 12/65/35. The structural and electrical properties of the composite films were investigated. Composites were developed with 1) improved AFE-to-FE domain switching with decreased AFE-to-FE transition field and increased saturation polarization for materials with AFE-type properties, 2) increased induced polarization with decreased coercivity and polarization remanence for relaxor-type composites and 3) increased hysteresis loop squareness for ferroelectric memory materials compared with films of homogeneous PLZT composition.