Titanium Vapor Research Articles

Energy-resolved mass spectroscopy of Ar–C 2H 2–N 2 plasma, performed during ion plating of TiC and TiN hard coatings

Energy-resolved mass spectroscopy studies during discharge in Ar+N 2 and Ar+C 2H 2 gas mixtures in a triode ion-plating apparatus (Balzers BAI 730) revealed a high degree of acetylene (C 2H 2) decomposition under typical conditions suitable for titanium evaporation. In the case of the Ar+C 2H 2 gas mixture, the most abundant neutral species besides argon is hydrogen, and not acetylene as would be expected. On the other hand, the 12C + ion is the most abundant carbon-containing species. The ratio between C +, CH 3 + and C 2H 2 + ions and titanium ions (Ti +, T 2+) decreases with increasing arc current. By careful adjustment of the discharge parameters, either a plasma rich in C x H y radicals with a low metal evaporation rate or plasma with a high evaporation rate but with almost completely decomposed acetylene, i.e. with C + and H n=1–3 + only, can be obtained.

XRD and AES characterization of TiO xN y thin films grown by ion assisted deposition

Compositional and phase characteristics of TiO x N y films synthesized by ion-assisted deposition at low substrate temperatures were investigated. The films were deposited by evaporation of titanium in a mixed oxygen/nitrogen gas atmosphere. The composition of films, mainly determined by coadsorption processes, was controlled by variations of the partial pressures of the two gases, their ratio, as well as by the ratio of the total pressure and the flux density of titanium atoms to the film surface. The ion assistance was carried out by bombardment with ionized ambient molecules with energies in the range of several hundred eV. The film composition was evaluated by Auger electron spectroscopy. Selected compounds, from Ti–N up to superior Ti-oxides, were analysed by X-ray diffraction. In general, amorphous films were obtained. At a low relative content of oxygen in the gas atmosphere, δ-TiN and ε-Ti 2N phases were observed although a small amount of oxygen in the films was detected. A formation of oxide phases, Magneli phases of the type Ti n O 2 n−1 , such as Ti 3O 5, Ti 7O 13 and Ti 10O 19, was observed at elevated relative densities of ion bombardment and increased O 2/N 2 gas ratios.

Atomic Structure of TiO Epitaxial Layers Deposited on the MgO(100) Surface

Impact-collision ion scattering spectroscopy was applied to study the geometrical structure of epitaxially grown TiO layers on the MgO(100) surface. Hetero-epitaxial TiO layer was formed by thermal evaporation of titanium onto the MgO(100) surface followed by the exposure to oxygen at 400℃. The well-ordered TiO structure was confirmed by the impact-collision ion scattering spectroscopy and reflection high energy electron diffraction patterns. It is revealed that the Ti and O atoms are located on the on-top site of the MgO(100) surface and the TiO overlayers are composed of little three dimensional islands.

イオンミキシング蒸着法によって作製したＴｉＮ薄膜の結晶配向性とピンホール欠陥

Titanium nitride (TiN) films were prepared onto stainless steels by nitrogen ion irradiation during titanium vapor deposition, i.e., ion mixing and vapor deposition (IVD) technique. The influence of preparation conditions on surface morphology, preferred orientation and microstructure of TiN films were investigated. The TiN films with preferred orientation of {111} or {100} plane were characterized by the respective appearance of triangular or grainy crystals, which were strongly dependent of preparation conditions. The area ratio of pinhole defects in the TiN films evaluated by electrochemical measurement successfully decreased with the orientation of plane preferring {100}. On the contrary, they increased with the orientation of plane preferring {111}. Here, the correlation between preferred orientation and pinhole defect of TiN films was discussed with the optimum preparation conditions for the corrosion-protective dry coating films.

Effect of preparation conditions on pinhole defect of TiN films by ion mixing and vapor deposition

Pinhole defects of titanium nitride (TiN) films prepared by nitrogen ion irradiation during titanium vapor deposition, ion mixing and vapor deposition (IVD) technique, were evaluated potentiodynamically in a deaerated 0.5 kmol/m 3 H 2SO 4+0.05 kmol/m 3 KSCN solution at 298 K. The nearly stoichiometric TiN films exhibited the columnar structure with the preferred crystal growth of (1 1 1) or (2 0 0) plane, and they contained more or less pinhole defects. The critical passivation current density (CPCD) i crit of TiN films decreased successfully with increasing film thickness and substrate temperature. Here, the area ratio of pinhole defects was evaluated by the ratio of i crit of coated and non-coated specimens, i.e., by CPCD method. Based on such electrochemical evaluation, the optimum preparation conditions for the corrosion-resistant TiN films were discussed.

Spectral plasma temperature determination of thermionic vacuum arc in the titanium vapors

The titanium vapor plasma generated by a thermionic vacuum arc was spectroscopically investigated. The electronic temperature was obtained using the method of spectral lines intensity ratios. Three sets of spectral lines have been used, each set having the same energetic lower level namely: fundamental, 170.132 cm−1 and 386.874 cm−1 respectively. For an arc current Iarc=1 A and an arc voltage Uarc=670 V, an average electronic temperature of plasma Te=(2860±587) K was obtained. Moreover, spectroscopic investigations of the interelectrodic plasma show that the discharge is totally sustained by evaporated anode material.

Kinetics of the Iodide Titanium Process by the Thermal Decomposition of Titanium Tetraiodide

An extensive study of the kinetics of the iodide titanium process, performed in a flow system by the thermal decomposition of titanium tetraiodide over a tungsten filament substrate, is presented in this paper. The influence of the substrate temperature, , and reactant pressure, , on the process rate has been analyzed. It has been found that the overall process is rate limited by the transfer of gases in the neighborhood of the substrate. In addition, it has been determined that the rate of titanium transfer is modulated at the filament surface by a certain deposition efficiency that depends on reactant pressure and reaction temperature. The available thermodynamic data for the gaseous titanium iodides at high temperatures fail to explain such an efficiency factor, although the calculations described herein indicate that such data are probably incorrect. Eventually, the titanium growth rate results from the noninterfering contributions of titanium deposition and evaporation rates. The overall reaction rate for the process can be expressed as a function of the operational parameters by the following equation: represents the determined deposition efficiency and the titanium evaporation rate in vacuum. Owing to the similarities between the iodide process for titanium and zirconium, the general characteristics for the titanium growth kinetics here described are expected to be also fulfilled for the zirconium case. © 2000 The Electrochemical Society. All rights reserved.

TiO 2−x films prepared by ion beam assisted deposition

TiO 2− x films were prepared by ion beam assisted deposition on an EATON Z-200 system, during which concurrent electron beam evaporation of titanium and bombardment with an inert gas ion beam were carried out in an O 2 atmosphere. Xe + and Ne + ions with different current density and incident angles were used. The films were investigated using X-ray diffraction (XRD), glancing incident X-ray diffraction (GIXRD), X-ray photoelectron spectroscopy (XPS) and Rutherford backscattering spectroscopy (RBS). RBS analysis shows that the films are nearly stoichiometric. XPS measurements reveal that the surface was fully oxidized, but Ti 2+, Ti 3+ and Ti 4+ coexist on the Ar +-sputtered surface. XRD and GIXRD analyses show that almost all the films have rutile-type structure and (2 0 0) preferred orientation. After annealing the 2 θ angle shift to higher degrees and the (2 0 0) peak intensity increases, which means better crystallization and orientation.

Evaluation of a flexible physical vapor deposited TiC–C coating system

Physical vapor deposited (PVD) TiC–C coatings with different amounts of free carbon have been investigated with respect to their microstructure, mechanical and tribological properties. The coatings were deposited using a plasma assisted PVD process which combines evaporation of titanium and sputtering of carbon. The carbon content was controlled by means of the magnetron power. X-ray photoelectron spectroscopy was used to study the chemical composition. X-ray diffraction and transmission electron microscopy were utilised to obtain information about phase composition and microstructure. It was found that the mechanical properties varied immensely with the carbon content in the coatings. Coating hardness and elastic modulus both decreased dramatically with increasing carbon content. The hardness dropped from 44 to 13 GPa, and the elastic modulus from 430 to 160 GPa, as the carbon content was increased from 43 to 70 at.%. All coatings provided very low friction coefficients, between 0.14 and 0.20, as tested against a steel ball in a ball-on-disc test. The TiC–C coating system proved to be easy to control with respect to mechanical properties. Together with good tribological properties this makes it possible to tailor these coatings to suite different applications as well as substrate materials.

Microstructure and secular instability of the (Ti1 − x,Alx)N films prepared by ion-beam-assisted-deposition

(Ti1 − x,Al x )N films were prepared by ion beam assisted deposition (IBAD). The films were synthesized by depositing titanium and aluminum metal individual vapor under simultaneous bombardment with nitrogen ions in the energy range of 0.2–20 keV with the (Ti1 − x,Al x )/N transport ratio in the range of 0.5–2.0. The films were formed onto Si(111) wafers at room temperature. Structural characterization of the films was performed with x-ray diffraction and selected area electron diffraction. The crystalline structure of the (Ti0.64,Al0.36)N and (Ti0.33,Al0.67)N films were found to be a metastable single-phase B1-NaCl structure. The (Ti0.29,Al0.71)N films revealed a two-phase mixture consisting of NaCl and wurtzite structural phases. The AlN solubility limit into TiN, which approximately equal with x value, calculated by using electron theory was about x = 0.65, which shows good agreement to the experimental results. Phase separation after half a year of aging at room temperature in air was observed on the (Ti0.33,Al0.67) films whose AlN content is close to the solubility limits.

The ultrastructure of the periodontal ligament cells-titanium interface with vitro

Several studies have shown that a peridontal ligament can form on titanium dental implants which were placed in contact with the periodontal ligament of the retained roots. However, the following question is still critical: how do the periodontal ligament cells adhere to the implant surface? Little is known about the ultrastructure of the periodontal ligament cells-titanium interface. The objective of this study, therefore, was to gain insight into the morphology of the interface. Human periodontal ligament cells were cultured on thin titanium substrates obtained by electron beam evaporation of titanium. This technique allowed for the preparation of ultra-thin sections for transmission electron microscopy containing titanium substrate as well as the cells adhering to it. Transmission electron microscopy showed that periodontal ligament cells not only came into close contacts with the titanium surface, but also extended numerous cellular processes that contained microfilaments and an electron-dense plaque. In addition, collagen fibres were observed in some zones of the extracellular matrix contacts. The results provide evidence that periodontal ligament cells can develop attachments on titanium surface.

In Situ Study of Titanium Film Growth On Different Substrates

AbstractThe chemical and microstructural properties of a surface have a strong influence on the growth mode and the morphology of a film evaporated onto this interface. Changes in the growth stress of thin titanium films, measured in situ by a cantilever beam technique, evaporated under UHV-conditions are used to monitor the chemical and microstructural properties of a substrate surface. The starting substrate film used in this study was a quasi single-crystalline TiO2-film (d=50 nm) prepared by reactive evaporation of titanium in an oxygen atmosphere and subsequent annealing (20 min, 400°C). The Ti-growth stress on this substrate is compressive up to monolayer coverage and tensile at higher film thickness, which is interpreted to indicate a strong interaction between TiO2 and the arriving Ti atoms at the interface during monolayer formation and strained (tensile) layer epitaxy at higher film thickness. In a second series of experiments the TiO2-film was covered with Al-overlayers of varying thickness. Due to oxygen interdiffusion from the TiO2-film an amorphous Al-oxide layer is formed at the interface eliminating the high degree of order of the substrate TiO2-film. On this amorphous substrate the stress vs. thickness curve of the Ti-film, in terms of our stress model, is interpreted to indicate island formation and growth of a polycrystalline Ti-film. At Al-layer thicknesses above about 3 nm the Al-interface becomes metallic. The structure of this Al-surface depends on the film thickness and substrate temperature during its deposition. During deposition of the first Ti-monolayer on metallic Al a large incremental tensile stress (up to 45 GPa) is measured. The magnitude of this tensile stress is closely related to the surface microstructure of the Al substrate. The surface roughness deduced from the tensile interface stress is compared with the surface roughness measured by AFM.For comparison, analogous experiments were made with Al2O3/Al substrate bilayers. The results of these experiments qualitatively agree with those on the TiO2/Al-substrate. The general shape of the stress vs. thickness curve is comparable, however quantitative differences are interpreted to be due to differences in the structure and/or chemical composition of the substrate Al-film.

Surface density of states on the (0001) face of titanium

A titanium microcrystal has been grown by the evaporation of titanium onto a tungsten field emitter. The titanium surface was kept clean by maintaining a residual gas pressure of 10−9 Pa in the vacuum chamber. The surface density of states on the (0001) face of titanium was determined by the photofield emission method using photon energies hν=1.963, 2.409, 2.497, 2.541 and 2.602eV. The full-potential linearized augmented plane wave method was used to calculate the surface density of electron states of Ti(0001). It is concluded that the photocurrent is dominated by photofield emission from a surface state which lies just below the Fermi energy, and that fine structure in the photocurrent is due to modulation of the density of final states by a set of narrowly spaced surface resonances.

Excitation states of titanium and nitrogen gas in an electron beam evaporation sustained arc

The arc discharge studied in this work was sustained by titanium vapor evaporated by an electron beam in nitrogen atmosphere. Optical emission spectroscopy and Langmuir probe diagnostics were carried out to study the excitation of titanium and nitrogen. It was found that with increasing arc current, Ti and nitrogen gas exhibited an opposite tendency of excitation. When arc current increased from 20 to 60 A, Ti was highly excited to Ti+, while the excitation of nitrogen was lowered; this is completely different from that for a conventional cathodic arc, where both Ti and N2 are highly ionized. By Langmuir probe diagnostics, the electron energy distribution followed a two-Maxwellian distribution at an arc current of 60 A; the electron temperatures were 0.98 and 10.1 eV, and the corresponding electron densities were 2.7×1011 and 3.9×109 cm3, respectively. This result provided a theoretical explanation for the difference of excitation between titanium and nitrogen in this arc.

Optical transitions in the titanium 〈0 0 0 1〉 band structure

Optical transitions in the bulk band structure of the titanium in the 〈0001〉 direction have been observed using the photofield emission method. In the photocurrent–voltage characteristic the optical excitations appear as shoulders. From the voltages at which the shoulders occur, final and initial energies are estimated and compared with theory. Measurements were made for s-polarized light and therefore excitations in the bulk are predominant. The results obtained for photon energies hν=1.96, 2.409, 2.497, 2.541 and 2.602eV are compared with the calculated band structure. These experimental results show that the excitations occur only between two bands and the bands should be considerably shifted, and the minimum of the lower band should be about 0.5eV below that calculated. Additionally, excitations from the titanium (0001) face are observed. A single microcrystal of titanium was obtained by evaporation of titanium onto the tungsten tip emitter in ultra-high vacuum.

Solid-state deoxidation of niobium by vacuum-deposited titanium

A two-step deoxidation of niobium was proposed as an alternative for titanium external gettering. The proposal was confirmed experimentally. Titanium vapor from the melt was deposited in vacuum on the free surface of niobium samples, and the deposited samples were subsequently annealed to diffuse oxygen from the Nb bulk to the Ti coating layer. Due to the radiation heat during the electron beam vacuum melting of Ti, deoxidation by the Ti deposit partially occurred. Electric resistivity measurements showed a hundreds times faster deoxidation in the subsequent annealing than during external gettering. This fast deoxidation could prevent Ti penetration into Nb. RRR measurements suggested that the annealing could be conducted at lower temperatures than for external gettering.

Synthesis, structure and reactivity of the hexaphospha-titanocene, bis-(η5-3,5-di-tert-butyl-1,2,4-triphosphacyclopentadienyl)titanium(II)

The novel, fully structurally characterised, 14e-titanocene [Ti(η5-(P3C2But2)2] made by (i) cocondensation of titanium vapour with the phosphaalkyne ButCP (ii) reaction of ButCP with [Ti(η6-C6H5Me)2] at –78 °C or (iii) by heating TiCln with n(KP3C2But2) (n = 2, 3) in toluene at 110 °C, undergoes an unusual [2+2] cycloaddition reaction with ButCP to give [Ti(η5-P3C2But2)(η3-η2-P4C3But3)].

ＩＶＤによる（Ａｌ，Ｔｉ）Ｎ薄膜の低温形成とその特性

(Al, Ti) N films were grown on silica and silicon substrates by aluminum and titanium vapor deposition and simultaneous nitrogen ion implantation under the conditions of the nitrogen ion energy of 2.0 keV and the atomic transport ratios of (Ti+ Al)/N of 0.5-1.5 and of Ti/(Ti+Al) of 0-1.0. The crystalline structure of the films depends on the atomic transport ratio of Ti/(Ti+Al). A single phase with Wurtzite or NaCl structure exists at Ti/(Ti+Al)≤0.17 or ≥0.25, and two phases with Wurtzite and NaCl structures at Ti/(Ti+Al)≈0.20. The surface morphology of the films is largely affected by titanium content. With an increase of Ti/(Ti+Al), the surface becomes fine. The microhardness of the films was found to have a maximum value in those films with two phases. The chemical bonds of Al-N and Si-N were identified in the interface between a (Al, Ti) N film and a silicon substrate by means of AES analysis. The metallic aluminum was not found in the interface of such films prepared at the atomic transport ratio of (Ti+Al)/N≤1.0.

Plasma diagnostics in a triode ion plating system*

Langmuir probes combined with an energy resolved mass analyzer make satisfying contributions to the characterization of plasmas. The probes provide spatially resolved information on the well known plasma parameters, while the mass analyzer gives information on the energy distribution functions for ions/neutrals originating from some point in the plasma volume. These diagnostic tools have been used to investigate the glow discharge of the triode ion plating system of Balzers (BAI 640), a physical vapor deposition installation for the production of hard coatings. Two identical, planar Langmuir probes, positioned in the main argon plasma body, and an energy-resolved mass analyzer (Balzers PPM 421), directed to the crucible, were used to investigate the influence of the four most important process parameters, i.e., (1) the low voltage (LV) arc current, (2) the high voltage (HV) electron gun current, (3) the total pressure, and (4) the substrate voltage on the plasma parameters and on the energy spectra of ions and neutrals, during the evaporation of titanium without reactive gases. The substrate bias had no significant influence on the plasma parameters and on the energy spectra, but is very important for the microstructure of the thin film. The HV electron gun, used to melt the titanium, changed the plasma parameters only at high current values, but the energy spectra of the Ti ions changed drastically. The LV arc current and the total pressure are the process parameters that do affect both the probe characteristics and the energy spectra of ions and neutrals.

Ion beam assisted deposition of carbide and carbonitride of titanium at low substrate temperature

Ion beam assisted deposition was used to form titanium carbide and carbonitride films on glass, silicon and low alloy steel by electron beam evaporation of titanium in an atmosphere of ethene or a nitrogen/ethene gas mixture under bombardment with argon ions. Over a wide process parameter range, the films were formed as monophase material with varying composition. Oxygen contaminations from residual gas reactions decreased with increasing ion irradiation intensity. Hardness measurements showed a strong dependence of the hardness on the process parameters, particularly the ion-to-atom arrival ratio. Adhesion and corrosion behaviour were determined by scratch test and electrochemical measurements. It turns out that both features can be improved when a thin titanium metal film is deposited onto the substrate prior to formation of the ceramic film. These results look promising for application of the films as mechanical and chemical protection on temperature sensitive substrates such as heat-treated steels and aluminum alloys.