Epitaxial BaZrO3 tracks by electrospinning of metalorganic fibers on single crystals

Abstract

Electrospinning was used to produce fibers of barium zirconate (BZO) by metalorganic decomposition. Using short deposition times, a low density of randomly distributed fibers were deposited on lanthanum aluminate single crystals with (100) orientation. Then the films were subjected to thermal treatment at 600 °C and 800 °C to decompose the organic matter and crystallize the perovskite phase. X-ray diffraction, field-emission electron and atomic force microscopies were used as characterization tools. Continuous BZO tracks are obtained after removal of organics at 600 °C. At 800 °C, cube-on-cube heteroepitaxy of barium zirconate with respect to the lanthanum aluminate template was detected by synchrotron X-ray diffraction, although a fraction of misoriented BaZrO₃ crystals were also detected by grazing incidence X-ray diffraction (GIXRD). For precursor fibers closely attached to the single crystal surface, BaZrO₃ grows as epitaxial nanoparticles, which then coarsen and self-organize along the fiber tracks, showing oscillations in the interparticle separation distance. Growth of the coarsened low-aspect ratio crystals follows an anisotropic atomic diffusion mechanism, in which mass transport mainly occurs in the direction of the initially deposited fiber. The misoriented nanoparticles observed by GIXRD are attributed to the fibers deposited on top of those arriving first to the substrate and to the loss of the interfacial epitaxial growth at large crystal thickness. The distribution and morphology of the particles have been further analyzed by means of atomic force microscopy.