X‐ray photoelectron spectroscopy‐based valence band spectra of passive films on titanium

Abstract

Titanium (Ti) is always covered by thin passive films. Thus, valence band (VB) spectra, obtained using X‐ray photoelectron spectroscopy (XPS), are superpositions of the VB spectra of passive films and that of the metallic Ti substrate. In this study, to obtain the VB spectra only of passive films, angular resolution (for eliminating the substrate Ti contribution) and argon ion sputtering (for removing passive films) were used along with XPS. The passive film on Ti was determined to consist of a very thin TiO2layer with small amounts of Ti2O3, TiO, hydroxyl groups, and water with a thickness of 5.9 nm. The VB spectra of Ti were deconvoluted into four peak components: a peak at ~1 eV, attributed to the Ti metal substrate; a broad peak in the 3–10 eV range, mainly attributed to O 2p (~6 eV) and O 2p‐Ti 3d hybridized states (~8 eV), owing to the π (non‐bonding) and σ (bonding) orbitals in the passive oxide film; and a peak at ~13 eV, attributed to the 3σ orbital of O 2p as OH−or H2O. The VB region spectrum between approximately 3 and 14 eV from Ti is originating from the passive film on Ti. In particular, characterization of VB spectrum obtained with a takeoff angle of less than 24° is effective to obtain VB spectrum only from the passive film on Ti. The property as n‐type semiconductor of the passive film on Ti is probably higher than that of rutile TiO2ceramics.

Electrochemical corrosion behavior of Ti‐3Mo alloy under different accelerated corrosion tests

“…In general, the stability and corrosion resistance of the oxide film can be evaluated according to the ratio of O 2 − /OH − . [ 48 ] As shown in Figure 13, the atomic percentage of O 2 − species decreased with an increase in the current density, and the atomic percentage of TiO 2 also decreased correspondingly. Normally, the high ratio of TiO 2 /Ti 2 O 3 implied better stability and protection.…”

Improving the Adhesion of Multi-Walled Carbon Nanotubes to Titanium by Irradiating the Interface with He+ Ions: Atomic Force Microscopy and X-ray Photoelectron Spectroscopy Study

“…In the following, we will only consider the most intense Ti 2p 3/2 spectrum. In this spectrum of the “MWCNT/Ti” system before and after irradiation, three components are observed, which correspond to metallic titanium atoms (~454.2 eV, Ti1), partially oxidized titanium atoms in TiO 1−x and TiO 2−x (~456.4 eV, Ti2), as well as titanium atoms in TiO 2 (~458.4 eV, Ti3) [ 28 , 29 , 30 ]. It should be noted that the PE lines of TiO 1−x and TiO 2−x oxides in our previous study [ 8 ] were considered separate components, but due to difficulties of approximation, in this work, they were combined into one component.…”