Preparation and characterization of Pb(Zr0.53Ti0.47)O3/CoFe2O4 composite thick films by hybrid sol–gel processing

Pb(Zr0.53Ti0.47)O3/CoFe2O4 (PZT/CFO) multiferroic thick films were prepared using hybridized sol–gel processing and followed by systematic characterization investigations. PZT sol–gel solution, PZT and CFO nanopowders were used to fabricate the PZT/CFO thick films on Pt/Ti/SiO2/Si substrate. In this process, sol–gel solution was employed as the buffer layer between the substrate and thick films, the capping layer on the top of thick films; it was also mixed with PZT nanopowder for obtaining and adjusting homogenerous slurry, and to disperse CFO nanopowder into it to form heterogenerous slurry. PZT sol–gel solution and two kinds of slurry were spin-coated onto the substrate layer by layer and then annealed. X-ray diffraction results showed that PZT and CFO phases coexisted in the thick films without any other detectable impurity phase. SEM micrographs of thick film cross-sections exhibited composite structures without any visible boundary between different layers. With increasing annealing temperature, PZT/CFO multiferroic thick films became porous and the bottom electrode (Pt) was peeling off from the substrate above 700 °C due to Ti diffusion into Pt layer. Their thickness observed from SEM cross-sectional pictures is 3.31 μm annealed at 600 °C and 2.63 μm annealed at 650 °C. Ferroelectric and ferromagnetic properties of thick films were measured, evidencing the multifunctional properties in these films.