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

Abstract

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 (α) phase and orthorhombic (β) 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) α to α (α−α); (ii) α−α−β; (iii) β to β (β−β); (iv) β to α (β−α); and (v) α−β−α phase transitions at elevated temperatures ranging from 80 to 750 K.

An efficient methodology for measurement of the average electrical properties of single one-dimensional NiO nanorods

“…In this study, we are able to synthesize large-area arrays of vertical-aligned 1D NiO nanorods using the hot-filament metal-oxide vapor deposition (HFMOVD) technique. This technique has become very important, because it can be used to synthesize a variety of metal-oxide101617181920212223242526 and metal27282930 nanostructures with diverse morphological features and crystalline traits. The 1D NiO nanorods thus produced were then characterized by field-emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), x-ray diffractometry (XRD) and ultraviolet-visible spectroscopy.…”

One‐Dimensional Metal‐Oxide Nanostructures: Recent Developments in Synthesis, Characterization, and Applications

“…HFMOVD28–31, 42, 99–101 can be classified as one of the CVD techniques because of its similarity to conventional hot‐filament chemical vapor deposition (HFCVD) techniques. However, the hot‐filaments in the HFMOVD not only play an assistant role during deposition, but also become metal‐vapor sources at high temperatures.…”

“…As a consequence of the VS growth mechanism, materials anisotropically gain along the preferential axis to form the 1D morphology. There are three processes involved in the VS growth mechanism for the synthesis of 1D metal‐oxide nanostructures by the HFMOVD technique:28–31, 42, 99–101 i) thermal sublimation from the hot metal filament, ii) chemical vapor reaction of the sublimated heavy metal vapor with ambient oxygen gas, and iii) condensation of the heavy metal‐oxide vapor into 1D nanostructures.…”

“…A schematic representation of the VS growth mechanism is shown in Figure . For the case where a heavy tantalum vapor sublimates from a hot tantalum filament at 1700 °C and the chamber pressure is 1 × 10 −2 Torr,30, 100, 101 we have the formula …”

“…Enormous efforts have so far been made to synthesize and characterize 1D metal‐oxide nanostructures in the forms of rods,27–31 wires,32–34 needles,35, 36 tubes,37, 38 belts,39–41 hooks,42 cables (i.e., coaxial wires),43, 44 ribbons,45, 46 fibers,47 tips,48 helices (or spirals),49, 50 and zigzags 50. The 1D forms can enhance the unique properties of the material, making them suitable for a wide variety of applications such as biosensors,51, 52 gas sensors,53–55 smart windows,56–58 solar cells,59–63 supercapacitors,64, 65 photodetectors,66–68 light‐emitting diodes,69 field emissions,70, 71 and field‐effect transistors 72–75.…”