Preparation and characterization of Pb(Zr_0.53Ti_0.47)O₃/CoFe₂O₄ composite thick films by hybrid sol-gel processing

Pb(Zr_0.53Ti_0.47)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. Crown