Ti Ion Concentration Research Articles

Effects of different Ti concentrations doping on Li2MnO3 cathode material for lithium-ion batteries via density functional theory

Li2MnO3 is extensively studied for a cathode material in lithium-ion batteries because of its high voltage and specific capacity. Nevertheless, it has the disadvantages due to low conductivity and Li-ion diffusion. To modify its performance, we determine the structure stability and electronic properties of Li2MnO3 cathodes doped with different Ti-ion concentrations using the spin-polarized density functional theory including the Hubbard term (DFT + U). For the calculations, cell parameters, formation energies, band gaps, total density of states, partial density of states and stability voltages are determined. The results highlight that the expansion of the cell volumes by Ti-ion impurities has a positive effect on the diffusion of Li ions in these cathodes. Because of the minor voltage changes, Li2MnO3 cathode doped with a Ti-ion concentration of 0.250 exhibits the highest voltage stability. Overall, these results are effective for the lithium-ion battery application based on Ti-doped Li2MnO3 cathodes.

Effects of Temperature, Ti(III) Ion Concentration, and Current Density on Electrodeposition of Ti Films in LiF–LiCl Melt

The effects of temperature, Ti(III) ion concentration, and current density on the electrodeposition of Ti films were investigated in the eutectic LiF–LiCl melt at 823–973 K. The Ti(III) ions were prepared by adding Li2TiF6 and Ti metal to the melt. The diffusion coefficients of Ti(III) were 1.4, 1.8, 2.3, and 3.2 × 10−5 m2 s−1, at 823, 873, 923, and 973 K, respectively. Galvanostatic electrolysis was conducted at 823–973 K. The surface roughness (S a) of the Ti films decreases with decreasing temperature. Thus, the electrodeposition of Ti films was conducted at the lowest temperature of 823 K with various Li3TiF6 concentrations (0.55–7.1 mol%) and cathodic current densities (50–1200 mA cm−2). The S a was lower at higher Ti(III) ion concentrations and lower current densities. The smoothest Ti films with a S a of 1.23 μm and a thickness of 10 μm were obtained at a cathodic current density of 50 mA cm−2 and Li3TiF6 concentration of 7.1 mol%.

Ti-Ions and/or Particles in Saliva Potentially Aggravate Dental Implant Corrosion.

The corrosive titanium products in peri-implant tissues are a potential risk factor for peri-implantitis. There is very limited information available on the effect of the corrosion and wear products on the dental implant corrosion. Therefore, we determined the influence of Ti-ions and Ti-particles on Ti corrosion. Eighteen commercially pure-Ti-grade-2 discs were polished to mirror-shine. Samples were divided into six groups (n = 3) as a function of electrolytes; (A) Artificial saliva (AS), (B) AS with Ti-ions (the electrolyte from group A, after corrosion), (C) AS with Ti-particles 10 ppm (D) AS with Ti-particles 20 ppm, (E) AS with Ti-ions 10 ppm, and (F) AS with Ti-ions 20 ppm. Using Tafel’s method, corrosion potential (Ecorr) and current density (Icorr) were estimated from potentiodynamic curves. Electrochemical Impedance Spectroscopy (EIS) data were used to construct Nyquist and Bode plots, and an equivalent electrical circuit was used to assess the corrosion kinetics. The corroded surfaces were examined through a 3D-white-light microscope and scanning electronic microscopy. The data demonstrated that the concentration of Ti-ions and corrosion rate (Icorr) are strongly correlated (r = 0.997, p = 0.046). This study indicated that high Ti-ion concentration potentially aggravates corrosion. Under such a severe corrosion environment, there is a potential risk of increased implant associated adverse tissue reactions.

Optimization of Electrolysis Conditions for Ti Film Electrodeposition from LiF – LiCl Eutectic Molten Salt

1. IntroductionTitanium is known as a metal which has excellent properties such as high specific strength and high corrosion resistance. However, there are two problems that prevent widespread use of titanium. One is the high smelting cost and the other is the poor workability. As a method to solve these problems, titanium plating is an attractive technique because superior surface properties of titanium can be utilized. For some applications, physical vapor deposition (PVD) is practically used as a titanium plating method. However, the PVD method has high plating cost and can be used for only simple-shaped substrates. On the other hand, electrodeposition of titanium in high-temperature molten salt is a promising plating method which is expected to have lower cost and can be used for complex shaped substrates. Accordingly, there have been many reports on the titanium electrodeposition in high-temperature molten salts [1–3].We have already reported the electrochemical behaviors of Ti(III) ions and the electrodeposition of titanium in KF–KCl and LiF–LiCl molten salts [4–7]. Furthermore, we found that LiF–LiCl has an advantage for electrodepositing smooth titanium films due to its lower melting point (774 K at the eutectic composition [8]); smoother titanium films were obtained at lower temperature by suppressing grain growth of titanium [9]. Thus, in the present study, we investigated the effect of electrolysis conditions such as current density and concentration of Ti(III) ions on smoothness of titanium films in LiF–LiCl eutectic molten salt.2. ExperimentalThe experiments were conducted in LiF–LiCl eutectic molten salt in an Ar glove box at 823 K. Li2TiF6(0.50–5.0 mol%) and Ti sponge (0.33–3.3 mol%) were added to the bath and Ti(IV) ions were converted to Ti(III) ions by comproportionation reaction. Ni plate, Mo flag, and Au flag electrodes were used as the working electrode. The counter and reference electrodes were Ti rods. The potential of the reference electrode was calibrated by Cl2/Cl− potential measured at a glass-like carbon rod electrode. Samples were prepared by galvanostatic electrolysis of Ni plate substrates. The samples were analyzed by SEM/EDX after washing with distilled water and 1M Al(NO3)3 aqueous solution to remove adhered salts.3. Result and DiscussionThe electrodeposition was carried out by changing the added amounts of Li2TiF6from 0.50 to 5.0 mol% and Ti sponge from 0.33 to 3.3 mol%. The cathodic current density was also varied from 25 to 1000 mA cm−2. The surface roughness of the obtained samples was measured by SEM. As a result, smooth Ti films were obtained at high Ti(III) concentrations and low current densities. As a typical example of the smooth film, Fig. 1 shows an appearance of the sample prepared at 50 mA cm−2 and 60 C cm−2 after addition of 3.0 mol% Li2TiF6and 2.0 mol% Ti sponge. The electrodeposited titanium film had metallic luster. Fig. 2 shows a cross-sectional SEM image of the film, indicating the smooth and compact deposit.In the poster session, the solubility of Ti(III) ions will be presented. Also, the effects of Ti(III) ion concentration and cathodic current density on the morphology will be discussed.AcknowledgementThe present address of Kouji Yasuda is Graduate School of Engineering, Kyoto University.

Excessive production of mitochondrion‑derived reactive oxygen species induced by titanium ions leads to autophagic cell death of osteoblasts via the SIRT3/SOD2 pathway

The incidence of peri-implant bone loss is high, and is a difficult condition to treat. Previous studies have shown that titanium (Ti) ions released from implants can lead to osteoblast cell damage, but the specific mechanisms have not been elucidated. The present study established a Ti ion damage osteoblast cell model. The levels of mitochondrion-derived reactive oxygen species (mROS) and autophagy, cell viability and the sirtuin 3 (SIRT3)/superoxide dismutase 2 (SOD2) pathway were examined in this model. It was found that Ti ions decreased osteoblast viability. Moreover, with increased Ti ion concentration, the expression levels of microtubule associated protein 1 light chain 3α (LC3) progressively increased, P62 decreased, autophagic flow increased and mROS levels increased. After the addition of an autophagy inhibitor Bafilomycin A1 and Mito-TEMPO, a mitochondrial antioxidant, the production of mROS was inhibited, the level of autophagy was decreased and cell activity was improved. In addition, with increased Ti ion concentration, the activity of SOD2 decreased, the acetylation level of SOD2 increased, the SIRT3 mRNA and protein expression levels decreased, and the activity of SIRT3 was significantly decreased. Furthermore, it was demonstrated that SIRT3 overexpression reduced the acetylation of SOD2 and increased the activity of SOD2, as well as reducing the production of mROS and the expression level of LC3, thus increasing cell viability. Therefore, the present results suggested that excessive production of mROS induced by Ti ions led to autophagic cell death of osteoblasts, which is dependent on the SIRT3/SOD2 pathway.

Utilizing alternate target deposition to increase the magnetoelectric effect at room temperature in a single phase M-type hexaferrite

Abstract

Electrochemical and biocompatibility examinations of high-pressure torsion processed titanium and Ti-13Nb-13Zr alloy.

The purpose of this study was to estimate the electrochemical behavior and biocompatibility of ultrafine-grained (UFG) commercially pure titanium (CPTi) and Ti-13Nb-13Zr (TNZ) alloy obtained by high-pressure torsion process. Electrochemical behavior of materials in artificial saliva at 37°C was evaluated by potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS), and the obtained results indicated that UFG TNZ alloy showed corrosion current density (jcorr =53 ± 5 nA cm-2 ) which was 2 times lower compared to coarse-grained (CG) TNZ alloy (jcorr =110 ± 12 nA cm-2 ) and higher corrosion resistance, while UFG CPTi and CPTi showed approximately the same corrosion rate (mean jcorr ∼ 38-40 nA cm-2 ). Static immersion test in artificial saliva, performed in this study, showed that the released ion concentrations from UFG materials were more than 10 times lower than the permitted concentration (the highest released Ti ion concentration from UFG CPTi and UFG TNZ alloy was 1.12 and 1.28 ppb, respectively, while permitted concentration was 15.5 ppb). The in vitro cytotoxicity tests, as the initial phase of the biocompatibility evaluation, showed that the fraction of surviving cells in all examined materials was much higher compared to the control sample and hence demonstrated absence of cytotoxicity and an increase of fibroblast cells adhesion on UFG materials surfaces. UFG CPTi and UFG TNZ alloy can be considered as promising materials for applications in dentistry due to high corrosion resistance and outstanding biocompatibility which were shown in this study. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1097-1107, 2018.

Processing, basic characterization and standard dielectric measurements on PLZT x/65/35 (2≤x≤13) ceramics

ABSTRACTThe influence of external stress (0-800bar) on the dielectric properties of PLZT x/65/35 (2≤x≤13) ceramics was investigated. Applying uniaxial pressure leads to a change in the peak intensity of the electric permittivity (ϵ), of its frequency dispersion as well as in the dielectric hysteresis. The peak intensity of ϵ becomes broader and shifts to lower temperatures for PLZT x/65/35 with x = 2, 4, 6, 7, 9.75, 10, 11 and 13, with increasing pressure, on heating. It was concluded that applying uniaxial pressure induces an increase of Tm, and thus has similar effects as the increase of the Ti ion concentration in the PZT system. Results based on nanoregion switching processes under combined electromechanical loading were interpreted. Surveys clearly demonstrated that applied stress has a significant influence on the dielectric properties of PLZT ceramics.

Processing, basic characterization and standard dielectric measurements on PLZT x/65/35 (4 ≤ x ≤ 11) ceramics

The influence of external stress (0–800 bar) on the dielectric properties of lead lanthanum zirconium titanate (PLZT) x/65/35 (4 ≤ x ≤ 11) ceramics was investigated. Applying uniaxial pressure leads to a change in the peak intensity of the electric permittivity (ϵ), in its frequency dispersion as well as in the dielectric hysteresis. The peak intensity of ϵ becomes broader and shifts to lower temperatures for PLZT x/65/35 with x = 4, 7, 9.75 and 11, with increasing pressure, on heating. It was concluded that applying uniaxial pressure induces an increase of Tm, and thus has a similar effect as the increase of the Ti ion concentration in the lead zirconium titanate (PZT) system. Results based on nanoregion switching processes under combined electromechanical loading were interpreted. Studies clearly showed that applied stress has a significant influence on the dielectric properties of PLZT ceramics.

Investigation to impurity content and micromorphology of high purity titanium powder prepared by molten salt electrolysis

In this work, the high purity Ti powder was prepared by molten salt electrolysis. The impurity content and micromorphology of Ti powder were systematically studied. The results showed that the main impurities in electrolytic Ti were Mn, Al, Cr, Fe, Ti, N, C and O, and the impurity originations and distributions were disclosed. Increase in the initial soluble Ti ion concentration can reduce the impurity content effectively. The electrolysis devices should be made by Ti alloy, which enables the impurity contents in Ti powder to be much lower than electrolysis devices made by other materials. After the electrolysis, the electrolytic Ti at the upside of cathode was platy bulk and dense, while the downside was loose powder. High current density and low soluble Ti concentration could produce dendritic and fine electrolytic Ti powder, and conversely, the electrolytic Ti powder was coarse polygon.

Dielectric properties of PLZT-x/65/35 (2≤x≤13) under mechanical stress, electric field and temperature loading

We investigated the effect of uniaxial pressure (0-1000 bars) applied parallely to the ac electric field on dielectric properties of PLZT-x/65/35 (2 \leqslant x \leqslant 13) ceramics. There was revealed a significant effect of the external stress on these properties. The application of uniaxial pressure leads to the change of the peak intensity of the electric permittivity (\varepsilon), of the frequency dispersion as well as of the dielectric hysteresis. The peak intensity $\varepsilon$ becomes diffused/sharpened and shifts to a higher/lower temperatures with increasing the pressure. It was concluded that the application of uniaxial pressure induces similar effects as increasing the Ti ion concentration in PZT system. We interpreted our results based on the domain switching processes under the action of combined electromechanical loading.

Ti-dopant-enhanced photocatalytic activity of a CaFe2O4/MgFe2O4 bulk heterojunction under visible-light irradiation

The effect substitution of Ti4+ at the Fe4+ site in a CaFe2O4-MgFe2O4 bulk hetero-junction (BH) lattice photocatalyst was explored and the Ti ion concentration was optimized to fabricate an efficient photocatalyst. A BH consisting of an optimum dopant concentration (Ti+4) level of x = 0.03 exhibited an increased band gap and generated a 1.5 times higher photocurrent. The newly fabricated Ti ion doped photocatalyst showed an enhanced quantum yield (upto ∼13.3%) for photodecomposition of a H2O-CH3OH mixture, as compared to its undoped BH counterpart under visible light (λ ≥ 420 nm). In contrast, the material doped with a very high Ti-dopant concentration displayed deteriorated photochemical properties. An efficient charge-separation induced by Ti-ion doping seems to be responsible for the higher photocatalytic activity in a doped bulk BH.

TiO 2 nanorod films grown on Si wafers by a nanodot-assisted hydrothermal growth

We report the controlled hydrothermal growth of rutile TiO 2 nanorods on Si wafers by using an anatase TiO 2 nanodot film as an assisted growth layer. The anatase nanodot film was prepared on the wafer by phase-separation-induced self-assembly and subsequent heat-treatment at 500 °C. The nanodots on the wafer were then subjected to hydrothermal treatment to induce the growth of rutile TiO 2 nanorod films. The size and dispersion density of the resulting TiO 2 nanorods could be varied by adjusting the Ti ion concentration in the growth solution. The TiO 2 nanorods were of the rutile phase and grew in the [001] direction. The growth mechanism reveals that the growth of the rutile nanorods was wholly dependent on the existence of rutile TiO 2 seeds, which could be formed by the dissolution–reprecipitation of the anatase nanodots during hydrothermal treatment or under the high-temperature conditions of the subsequent heat-treatment of the as-prepared nanodots. In controlling the rutile nanorod growth, the anatase nanodots show more efficiency than a dense anatase film. Preliminary evaluations of the rutile nanorod films have demonstrated that the wettability changed from highly hydrophobic to superhydrophilic and that the photocatalytic activity was enhanced with increasing nanorod dispersion density.

Soft and hybrid-doped Pb(Zr,Ti)O3 ceramics under stress, electric field, and temperature loading

We investigated the influence of uniaxial pressure (0–1000 bars) applied parallelly or perpendicularly to the ac or dc electric field (in a one-dimensional or two-dimensional manner) on dielectric and ferroelectric properties of selected soft and hybrid-doped PZT ceramics (1 mol. % Gd, 1 mol. % La and 1 mol. % (La+Fe)-doped Pb(Zr0.54Ti0.46) O3). Applying uniaxial pressure leads to a reduction of the peak intensity of the electric permittivity (ɛ), of the frequency dispersion, and of the dielectric hysteresis. The peak intensity of ɛ becomes diffused and shifts to a higher temperatures with increasing pressure. Simultaneous application of uniaxial pressure and dc electric field (perpendicular to each other) in the poling process implies in improvement of the ferroelectric properties, indicating a new possibility for poling materials with a high coercive field and/or high electric conductivity. It was also found that simultaneous application of uniaxial pressure and dc electric field (perpendicular to each other) allowed observation of the space charge in the depolarization process. The electrostrictive coefficient Q11 and differential permittivity were evaluated from obtained data. Our results show that applying uniaxial pressure induces similar effects as increasing the Ti-ion concentration in the PZT system. We interpreted our results based on the Cochran soft-mode and domain switching processes under the action of pressure.

Dependence of optical properties on doping metal, crystallite size and defect concentration of M-doped ZnO nanopowders (M = Al, Mg, Ti)

ZnO, Al-, Mg- and Ti-doped ZnO nanopowders were synthesized from CTAB-assisted oxalate intermediate by thermal decomposition method at 600°C in air. All samples presented a hexagonal wurtzite structure. The spherical nanoparticles assembled in a porous octahedron-like shape for all samples. The size of Al-doped ZnO nanopowders increased as a function of Al ion concentration whereas the size of Mg- and Ti-doped ZnO nanopowders decreased when Mg and Ti ion concentrations were increased. The increment and reduction of their sizes can be explained by the Zener pinning effect. The Eg value of Al-doped ZnO nanopowders slightly decreased when Al ions were increased due to the crystallite size and defect concentration increased. In contrast, the Eg value of Mg- and Ti-doped ZnO nanopowders increased as a function of Mg and Ti ion concentration which can be explained by the Moss–Burstein effect.

PLZT x/65/35 ceramics (x = 2 and 4) under electromechanical and temperature loading

The effect of uniaxial pressure (0–1000 bars) applied parallel to the ac electric field on dielectric properties of La-modified lead–zirconate–titanate, Pb(Ti,Zr)O3 (PZT), ceramics with Zr/Ti ratio of 65/35 was investigated. The experimental results revealed that applying uniaxial pressure leads to a reduction of the peak intensity of the electric permittivity (ε), of the frequency dispersion as well as of the dielectric hysteresis. Moreover, with increasing pressure, the peak intensity of ε becomes diffuse and shifts to a higher temperature. It was concluded that applying uniaxial pressure induces similar effects as increasing the Ti–ion concentration in PZT system. The obtained results were interpreted through Cochran soft-mode and domain switching processes under action of combined electromechanical loading. These studies clearly showed that the applied stress has significant influence on the dielectric properties of perovskite ceramics.

Influence of combined external stress and electric field on electric properties of 0.5% Fe-doped lead zirconate titanate ceramics

Influence of uniaxial pressure (0–1000 bars) applied parallel to or perpendicularly to the ac or dc electric field (in one-dimensional or two-dimensional manner) on dielectric and ferroelectric properties of hard lead zirconate titanate (PZT) ceramics were investigated. The experimental results revealed that applying uniaxial pressure leads to a reduction in the peak intensity of the electric permittivity (ε), of the frequency dispersion as well as of the dielectric hysteresis. Moreover, with increasing pressure the peak intensity of ε becomes diffused and shifts to a higher temperature. It was also found that simultaneous application of uniaxial pressure and electric field (perpendicular to each other) in the poling process improves the ferroelectric properties. This indeed indicates new possibility for poling materials with a high coercive field and/or high electric conductivity. The effects of uniaxial load are weaker than that obtained for soft PZT ceramics. It was concluded that applying uniaxial pressure induces similar effects as increasing the Ti ion concentration in PZT system. The obtained results were interpreted through Cochran soft mode and domain switching processes under applying of pressure.

Electric properties of soft PZT ceramics under combined electric and mechanic fields

The effect of uniaxial pressure (0–1000 bars) applied parallel or perpendicular to the ac electric field on electric properties of soft PZT ceramics has been investigated. It was found that uniaxial pressure significantly influences these properties. With increasing pressure the peak intensity in the ε(T) curve decreases, becomes diffuse and shifts to a higher temperature, dielectric hysteresis is reduced, and dielectric dispersion decreases. It was shown that the application of pressure perpendicular to the electric poling direction improves the ferroelectric properties. It was concluded, that applied uniaxial pressure or increasing Ti-ion concentration in PZT system induces similar effects. The results were discussed in term of Cochran soft-mode model and domain switching under influence of pressure.

An Investigation of Commercial Grade 2 Titanium as a Bipolar Plate Material for PEM Fuel Cells

Bipolar plates are one of the most important components in PEM fuel cell stacks. Currently, the commercial bipolar plates are made of non-porous graphite because of its chemical and thermal stability. However, they account for about 80% of the total weight and 45% of stack cost. In this study, commercial grade 2 titanium has been investigated as a possible bipolar plate material because its excellent corrosion resistance and relatively low density. Potentiodynamic, potentiostatic tests and EIS measurements were done to investigate the corrosion resistance in the simulated anode and cathode environments of a PEM fuel cell. SEM metallography was conducted to determine the corrosion morphology. ICP-OES tests were done to determine the metal ion concentrations in solution after corrosion. The Ti ion concentration in solution would be about 20ppm after 5000 hour operation at both the anode and the cathode.

Electroplating of TiB<SUB>2</SUB> in NaF-NaBF<SUB>4</SUB> Eutectic Melt with Titanium Fluoride

TiB 2 -Coated metal should be a very promising material for many purposes. One of the hardest problems on TiB 2 coating is to prevent cracking or stripping by thermal expansion gap between TiB 2 deposit and substrate. In this study, we have investigated the electroplating of TiB 2 in NaF-NaBF 4 eutectic melt(m.p.657K) with Na 2 TiF 6 or TiF 3 . The constant-potential electrolysis was carried out at various potentials. The electrodeposit was obtained at more negative potential than that of reduction of Ti(III) to Ti(II). The result of EPMA and XRD showed that the main ingredient of electrodeposit was TiB 2 . The morphology of electrodeposit changed remarkably at the potential where the cathodic current began to increase sharply in a voltammogram. The flat and adhesive deposit was obtained at more positive potential, while the electrodeposit became powdery at more negative potential. The morphology also changed with time, that is, the protuberant deposit grew with the current increase after a certain time even at the potential where the flat deposit was expected. The monitoring of current was important for depositing the thick and flat layer in this process, and the layer up to 50 μm was obtained under suitable conditions. The dependence ofthe morphology on Ti ion concentration or substrate was not critical in this process.