Fabrication of Barium Titanate Inverse Opals by Sol-Gel Electrophoretic Deposition Process

Barium titanate (BTO) inverse opal photonic crystals were fabricated by a process of self-assembly of polystyrene opal template in combination with electrophoretic deposition (EPD) of nanoparticles from BTO suspension. In this process, stable monodispersed suspension of BTO nanoparticles was prepared by dispersing BTO gel into a mixed solvent of 2-methoxyethanol and acethylacetone. Then the BTO nanoparticles were infilled into the interstices of the opal template formed by monodisperse polystyrene microspheres by electrophoretic deposition, and then polystyrene template was removed by calcining the specimen at a final temperature of 500oC. SEM images show that the inverse opals possess face-centered cubic (fcc) structure with center to center distant of the air spheres 310 nm. A photonic bandgap in the visible range is observed from reflection spectra of the sample. Such BTO inverse opals as photonic crystals should be useful in device applications.