Synthesis and Physicochemical Characterization of Metal (Zr, Ti, Zn, Mo) Oxide

Abstract

Deuterized ethanol exposed Zircaloy-4 (Zry-4) surfaces with various amount of C2D5OD exposures at 190 K were investigated. In TPD study, D2 was evolved at two different desorption temperature regions, the lower temperature feature at around 520 K showed first-order desorption kinetics. The high temperature desorption peak at around 650 K was shifted to lower desorption temperature as the exposure of C2D5OD increased. The Zr(MNV)o (oxide) peak revealed that metallic zirconium was oxidized by deuterized ethanol adsorption. After stepwise annealing of the oxidized Zry-4 sample up to 843 K, the Zr(MNV)o (oxide) peak was gradually decreased and the Zr(MNV)m (metallic) peak is increased. After the sample was heated to 843 K, the oxygen content near the Zry-4 surface was recovered to clean surface level. The concentration of carbon, however, was not recovered by annealing the sample. Titania nanofibers were synthesized by sol-gel coating of electrospun polymer nanofibers followed by calcining to form either the pure anatase or rutile phases. The average diameter of these ceramic nanofibers was observed to be around 200 nm for both the rutile and anatase forms. The valence band structure is different, however, the binding energy of Ti 2p is constant. Zinc oxide nanofibers doped with aluminum oxide were prepared by sol-gel processing and electrospinning techniques. The nanofibers had diameters in the range of 60~150nm. The incorporation of aluminum oxide resulted in a decrease in the crystallite sized of the zinc oxide nanofibers. Aluminum oxide doped zinc oxide (AOZO) nanofibers exhibited lower bandgap energies compared to undoped zinc oxide nanofibers. However, as the aluminum content was increased from 1.70 at.% to 3.20 at.% in the electrospinning solution, the bandgap energy increased resulting in lower conductivity. The electrical conductivity of the AOZO samples was found to depend on the amount of aluminum dopant in the matrix as reflected in the changes in oxidation state elucidated from XPS data. Sputter deposited Mo thin films on soda-lime glass are studied by X-ray photoelectron spectroscopy. It is found that the proportion of metallic Mo at the surface decreases and the number of Mo6+ species increases as the Ar gas pressure used for sputtering is increased. Sodium, sputtered from the substrate, is also detected on the surface of the Mo thin films. The surface behavior of zirconium oxide deposited Si(100) substrate depending on the different percentage of O2 in sputter gas is investigated by X-ray photoelectron spectroscopy (XPS) for study about the chemical environment of the elements, X-ray diffraction (XRD) for check the crystallinity of the films, spectroscopic ellipsometry (SE) technique for measuring the thickness of the films, atomic force microscope (AFM) for the morphology of the thin films. The zirconium oxide thin film was deposited on the Si(100) surfaces applying radio-frequency (RF) magnetron sputtering process successfully. The monoclinic ZrO2 and α-Zr crystal structure were observed, and decrease of the thickness is about 10 nm with increasing O2 concentration. The oxidation states of Zr 3d were changed from metal state to oxide state.