Fabrication, structural characterization, and formation mechanism of ferroelectric SrBi₂Ta₂O₉ nanotubes

Abstract

A capillary-enforced template-based method has been applied to fabricate strontium bismuth tantalate (SrBi₂Ta₂O₉, SBTO) nanotubes (diameter ~200 nm) by filling SBTO precursor solution into the nanochannels of porous anodic aluminum oxide (AAO) templates. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) equipped with Energy-dispersive X-ray spectroscopy (EDX) have been employed to characterize the morphology, structure, and composition of as-prepared nanotubes. XRD and selected-area electron diffraction (SAED) investigations demonstrated that postannealed (650 ° C for 1 h) SBTO nanotubes were polycrystalline with an orthorhombic perovskite crystal structure. The FE-SEM and TEM results showed that uniform length and diameter of SBTO nanotubes were obtained. The thickness of the SBTO nanotube walls was about 30 nm. High resolution TEM (HRTEM) analysis confirmed that the obtained SBTO nanotubes are made of randomly aligned nanoparticles 5-10 nm in size. EDX analysis demonstrated that stoichiometric SrBi₂Ta₂O₉ was formed. The possible formation mechanism of SBTO nanotubes in the AAO template is discussed.