X-ray Diffraction Study of a Large-Scale and High-Density Array of One-Dimensional Crystalline Tantalum Pentoxide Nanorods

In this study we synthesized a new morphological form of tantalum pentoxide (Ta2O5), one-dimensional (1D) nanorod arrays, via hot filament metal vapor deposition. Field-emission scanning electron microscopy (FESEM) showed the 1D Ta2O5 nanorods to be arranged in a large-area and high-density array about 20-25 nm wide and approximately 500 nm long. Energy dispersive spectroscopy (EDS) analysis verified the presence of only the elements Ta and O. X-ray diffractometry (XRD) revealed the crystalline nature of the 1D Ta2O5 nanorods, which included the tetragonal (alpha) phase and orthorhombic (beta) phases at a low temperature of 80 K. The XRD patterns of the 1D Ta2O5 nanorods indicated complex, polymorphic thermochromic phase transformations, which incorporate: (i) alpha to alpha (alpha-alpha); (ii) alpha-alpha-beta (iii) beta to beta (beta-beta); (iv) beta to alpha (beta-alpha); and (v) alpha-beta-alpha phase transitions at elevated temperatures ranging from 80 to 750 K.