Growth and electrochemical and optical properties of single crystalline vanadium pentoxide (V2O5) nanorod arrays were investigated. Vanadium pentoxide nanorod arrays were grown by electrochemical deposition, surface condensation induced by a pH change and sol electrophoretic deposition. Uniformly sized vanadium oxide nanorods with a length of about 10μm and diameters of 100 or 200nm were grown over a large area with near unidirectional alignment. TEM micrographs and electron diffraction patterns of V2O5 nanorods clearly show the single-crystalline nature of nanorods from all three growth routes with a growth direction of . The growth mechanisms of single crystal vanadium pentoxide nanorods have been discussed. The transmittance of nanorod arrays decrease more quickly under applied electric field than sol-gel derived film, which suggests nanorod array electrodes possess significantly improved charge/discharge rate. Electrochemical analysis is proves that nanorod arrays have higher efficiency than sol-gel derived film. The relationships between electrochemical and optical properties, nano and microstructures, and growth mechanisms have been discussed.
Template-based growth of single crystal V2O5 nanorods by either electrochemical or electrophoretic deposition was studied. Specifically, standard electrochemical deposition from VOSO4 solution, electrochemically induced deposition by local pH change of VO2+ solution, and electrophoretic deposition of nanoclusters in V2O5 sol were investigated. From each route, uniformly sized V2O5 nanorods about 10 μm in length were grown over large area with nearly unidirectional alignment, but with various extent of lateral shrinkage when fired at 500°C. These grown V2O5 nanorods all have the same single-crystal structure, regardless of deposition method and initial solutions or sol used.
Electrochromic materials are of interest for a wide variety of applications, such as displays and smart windows. Many electrochromic oxide materials are synthesized through sol-gel processing. We have demonstrated a general technique for the synthesis of oxide nanorods using sol electrophoretic deposition with an appropriate template. This technique can be applied for the synthesis of nanorods of electrochromic materials, such as TiO2, V2O5 and Nb2O5, with diameters of ~100 nm and a length of ~10 μm. By attaching these nanorods to a conducting substrate (such as ITO coated glass), it is possible to characterize the electrochromic behavior of these materials via UV-Vis absorbance spectroscopy. A similar technique has been used to make nanorods of the transparent conducting oxide indium tin oxide (ITO), which is often used as a working electrode in electrochromic devices. Such ITO nanorods have diameters of ~75-140 nm and lengths up to 60 μm.
We developed an interferometric borehole radar system, which has one transmitter and two receivers. A new analog optical link is equipped in this new borehole radar system. Field experiments were carried out and the system was evaluated. Clear reflections from subsurface fractures were observed. Two radar profiles can be obtained by one measurement. These two radar profiles are acquired by two receivers spacing 1 m apart, therefore these profiles can be used for interferometry. The difference in these profiles is caused only from the different of the wave paths from the radar target. By interferometric interpretation, much detailed information can be obtained from borehole radar compared to the conventional technique. For example, the direct coupling component of the received signal can be used for electromagnetic well logging.