Tuning the size and density of faceted Co3O4nanoparticles in LaBaCo2O5.5+δepitaxial thin films by strain engineering

Abstract

Both LaBaCo2O5.5+δ (LBCO) thin films and Co3O4 nanocrystals have potential applications in clean energy storage and ethanol gas detection. Herein, we report that the composite films of LaBaCo2O5.5+δ (LBCO) and {111} faceted Co3O4 nanoparticles were fabricated on (La,Sr)(Al,Ta)O3 (LSAT) and SrTiO3 (STO) substrates by magnetron sputtering deposition. The LBCO films revealed an epitaxial growth on both substrates with atomically sharp interfaces and a cubic-on-cubic orientation relationship. The Co3O4 particles were found to form at a very early stage of the film deposition and have the orientation relationship of [100]Co3O4//[100]LBCO and (100)Co3O4//(100)LBCO with the LBCO film matrix. It was found that the size and density of the Co3O4 particles can be tuned using different substrates, which induces different strains in the films. By means of high-resolution scanning transmission electron microscopy, the 3-dimensional morphology of the Co3O4 particles was illustrated. The formation and growth of the Co3O4 particles are discussed with respect to the strains of the films induced from the substrates.