Effect Of Titanium Doping Research Articles

Investigation of Ti-DLC film for the near infrared photodetector

Diamond-like carbon (DLC) combines the excellent properties of diamond and graphite and has the feature of a tunable band gap, which can be used as a photodetector. Here, we propose a Ti-DLC/Si heterojunction photodetector. Uniform DLC films were co-deposited on silicon by magnetron sputtering, and the effect of titanium doping on the films was investigated. Meanwhile, Ti-DLC/Si heterojunctions were prepared, and the optical responsiveness of DLC devices with different thicknesses was investigated in the 1550 nm band. The device exhibited a detectivity of 1.16 × 108 Jones, a response time of 5 ms for rising edges and 3 ms for falling edges at a DLC thickness of 90 nm. This work presents a broad application prospect in the field of photodetectors.

Effect of Titanium doping on structural and photo degradation properties of ZnO thin films

The ZnO and Ti:ZnO thin films were deposited on ordinary glass, quartz glass, substrates by sol–gel spin coating. The atomic percent (at.%) of Titanium (Ti) in ZnO is varied from 1 to 6. The deposited thin films were characterized by Grazing Incidence X-ray diffraction (GIXRD) and Raman spectroscopy for structural determination, High - resolution Scanning Electron Microscopy (HRSEM) to determine microstructure and photo degradation studies. The structure of the films is determined by Grazing Incidence X-ray diffraction (GIXRD) and is observed to be Hexagonal wurtzite with (002) orientation. The intensity of (002) decrease with increasing Ti at.%. The grain size is 20 nm and is decreasing to 10 nm with increasing Ti at.%. The HRSEM images of Ti (1%):ZnO and Ti (6%):ZnO thin films reveals that the films were nanocrystalline. The Raman spectrum reveals that the films turn to polycrystalline to nanocrystalline with increasing Ti at.%. The films were shown good response to methylene blue. The fast degradation of methylene blue was observed in case of Ti (1%):ZnO films.

Structural, electrical properties and complex impedance analysis of Pr0.67Ba0.22Sr0.11Mn1−xTixO3 perovskites

The Pr0.67Ba0.22Sr0.11Mn1−xTixO3 (x = 0.05 and 0.075) manganites are synthesized using solid-state reaction route. All XRD patterns with narrow and intense diffraction peaks reveal that the samples are well crystallized. For electrical properties we measure the conductivity versus temperature (80–400 K) and frequencies (40 Hz–10 MHz). These measurements were made by admittance spectroscopy technique. The effect of titanium doping on the electrical properties of our compounds appears by semiconductor behavior. The variation of DC-conductivity with temperature presents two metal–semiconductor transitions. The first transition TMS bound by Mn3+/Mn4+ ratio but the second transition TSM depends to an extrinsic effect of grain boundaries. It was observed also that the conductivity decreases with titanium concentration, such behavior is associated to a reduction of double-exchange mechanism. The conduction mechanism is explained by thermally activated hopping of small polaron at high temperature range. The activation energy was evaluated of about Ea = 30 m eV for x = 0.05 and Ea = 61 meV for x = 0.075. The total conductance spectrum of Pr0.67Ba0.22Sr0.11Mn0.925Ti0.075O3 compound is well described by the Jonscher power law: $$G\left(w\right)={G}_{dc }+A{\omega }^{n}$$ . Impedance study for the sample with x = 0.075 indicates the presence tow metal–semiconductor transitions and a non-Debye relaxation phenomenon related to a grain and grain boundary medium. Also, the modulation of the material by an electrical equivalent circuit show high values of grain boundary medium capacity.

Effect of Titanium Doping on the Electrical Properties of Conducting ZnO Transparent Thin Films

ZnO transparent conductive thin films are the most prominent substitute materials in the development of Ti-oxide thin films. Zinc oxide is a unique material that exhibits dual properties; semiconducting and piezoelectric. In this paper,a comprehensive study of crystalline size using X-Ray diffraction patterns and TEM images of Ti-doped ZnO with nano TiO2 in rutile phase is made to understand the development and growth of nano devices. ZnO has higher excitation binding energy approximately 60 MeV which is multifunctional and can be utilized in the field of ferroelectric, ferromagnetic and piezoelectric materials.Ti-doped ZnO-based semiconductors and nanowire devices are also of great importance for the integration on a single chip. ZnO nanomaterials can also be applied for biosensors, UV detectors etc. Ti-doped ZnO shows ferromagnetic behavior at room temperature. Also a reviewed is done on the recent activities and progress of ZnO nanomaterial with the brief discussion of applications of ZnO low dimensional structure. Using chemical bath deposition (CBD) technique, Ti-doped ZnO thin films are successfully synthesized. The crystalline size is determined by X-ray diffraction. For the analysis of surface morphology, TEM is used. The dielectric properties and electrical conductivity of the synthesized film are analyzed at different temperature and frequencies

Effect of titanium doping on conductivity, density of states and conduction mechanism in ZnO thin film

High quality, ~ 120 nm thin ZnO and Ti-doped ZnO (TZO) films were deposited on silicon substrates using magnetron co-sputtering technique. Surface roughness of the films was ~ 2 nm. Ti incorporation effect on the structure, morphology, conductivity, density of states (DOS) and conduction mechanism was investigated in detail. Ti ions were incorporated in the interstitial sites of hexagonal ZnO lattice. Average crystallite size increased from ~ 16.63 to ~ 19.08 nm upon Ti doping in ZnO film. Conduction mechanism changed from overlapping large polaron tunneling (OLPT) for undoped ZnO film to corelated barrier hopping (CBH) for TZO film. The experimental data were fitted theoretically using OLPT and CBH models to calculate frequency and temperature-dependent DOS. An enhancement of ac conductivity and DOS was observed with the doping of Ti in ZnO thin film. Complex modulus study of TZO film revealed transition from long-range mobility to short-range mobility with increase in frequency.

Effect of titanium doping on the compositional homogeneity of hollow glass microsphere

Titanium doped hollow glass microspheres (HGMs) were fabricated by sol-gel method. There were two kinds of spheres, blue and colorless, in each batch of HGMs. To study the effect of titanium doping on the compositional homogeneity and the difference between the two classes of HGMs, titanium doped gel precursors and HGMs were characterized by XRD, XRF, SIMS, SEM and EDS. The results showed that precipitation of alkali chlorides reduced the uniformity of heavily doped gel precursors and increased the dispersions of doping concentration in batches of HGMs. Because of the movability and flowability at high temperature, the uniformities of alkali metals were relatively poor in all HGMs. The DSIMS depth profiles of HGMs showed that local loss and accumulation of glass network modifiers, especially alkali metals, occurred in the outer and inner surface layers in dozens of nanometers as a result of volatilization and migration in furnace. Titanium behaved as both glass network former and modifier and its uniformity was between that of alkali metals and silicon. In blue HGMs, crystallization and segregation of titanium oxide, furthermore, reduced the compositional homogeneity of blue spheres in comparison to that of the colorless one.

The effect of titanium doping on carbon behavior in tungsten: A first-principles study

We investigated the structural and mechanical properties, the solution and diffusion behavior of carbon atom in the W–Ti lattice from first-principles calculations. The single C atom is energetically most favorable sitting at the octahedral interstitial site (OIS) nearest neighboring to the Ti atom in the W–Ti lattice. The minimum solution energy is about 0.874eV. It is shown that the effect of titanium doping on the carbon migration behavior is small, while the migration energy barrier is quite high, and the highest energy barrier is up to 1.60eV. Based on the elastic constants analysis, titanium doping tungsten can compensate the degradation of mechanical strength induced by carbon impurities. On the other hand, it is found that the ductility of pure W metal and W–Ti alloys is improved substantially by carbon impurities from the B/G ratio and the Poisson's ratio ν. The effect of the improved ductility is more obvious in pure W than that in the W–Ti alloys. In addition, substitutional C atom is better than interstitial C atom in terms of enhancing the ductility of pure W.

Effect of titanium doping on chemical and structural stability and electrical properties of proton-conducting solid electrolyte BaCe0.8Sm0.2O3−δ

In this study, the effects of Ti substitution for Ce on chemical and structural stability and electrical properties of proton-conducting solid electrolyte membrane BaCe0.8−xTixSm0.2O3−δ (BCST) are investigated. Our results show that both chemical and structural stability of the BCST samples in CO2 containing and moist atmospheres are remarkably enhanced with increasing the content of Ti which is higher electronegative than Ce. However, the proton conductivity of the sample decreases with increasing Ti content, which may be due to the increasing difficulty of lattice hydration and smaller grain size (corresponding to more grain boundaries) caused by Ti doping. The activation energy for proton migration increases with Ti content, which is mainly related with the weaker hydrogen bond. The results show that the BaCe0.75Ti0.05Sm0.2O3−δ has a great electrical conductivity (1.03×10−2Scm−1 at 650°C) and it also demonstrates good chemical and structural stability in CO2 and water containing atmospheres. Therefore, BaCe0.75Ti0.05Sm0.2O3−δ can be considered as a promising proton conducting electrolyte for intermediate temperature solid oxide fuel cells.

Effect of titanium doping on accumulation and annealing of radiation defects in austenitic steel 16Cr15Ni3Mo(0-1)Ti at low temperature (80 K) electron irradiation

The effect of titanium doping on accumulation and annealing of radiation defects was investigated in austenitic stainless steel 16Cr15Ni3Mo under low temperature (80 K) electron irradiation. Steel has been taken in the quenched, aged and separation of solid solution states. The data obtained on the accumulation of radiation defects and their evolution during isochronous annealing. The types of defects and its complexes and the activation energy of the processes taking place with their participation is identified. The mechanisms of radiation- induced processes and the effect of titan doping is discussed.

Effect of titanium doping on the structure and reducibility of nanoparticle molybdenum dioxide

Molybdenum dioxide (MoO2) has potential not only in heterogeneous catalysis, but also as an electrode material in lithium-ion batteries and fuel cells. However, the reduction tendency to molybdenum metal is a limiting factor in the use of this oxide. In the present work, MoO2 was doped with Titanium (Ti4+) to increase the stability to reduction in a hydrogen-rich environment. Rather than using a conventional high-temperature solid-state reaction, a novel solution-based synthesis method followed by hydrothermal reduction was used. Nano-sized Ti-doped MoO2 particles with Ti/Mo atomic ratios of 0, 0.03, and 0.05 were prepared and characterized. X-ray and time-of-flight neutron powder diffraction (XRD and NPD) confirmed the presence of only the MoO2 phase. Transmission electron microscopy showed that the nanoparticles had an acicular morphology with particle sizes in the long dimension between 30 and 50 nm. Elemental mapping obtained by scanning electron microscopy with energy dispersive spectroscopy showed homogenous distribution of the dopant. Attenuated total reflectance-Fourier transform infrared spectroscopy revealed that the solubility limit of the synthesized Ti-doped MoO2 was reached at a Ti/Mo ratio of 0.05. This observation indicates that the bulk thermodynamic solubility limit can be exceeded at the nanoscale. X-ray photoelectron spectroscopy performed on 0.03 Ti-doped MoO2 samples showed that the Ti dopant is present as Ti4+ and the depth profile analysis indicated the presence of this species even in the bulk of the sample. This agrees with the data obtained from Rietveld refinement of the XRD and NPD results, which showed changes in the lattice parameters and Mo–Mo interatomic distance upon doping, suggesting a substitution of Mo4+ by Ti4+. The effect of Ti doping on the reducibility of MoO2 was demonstrated by in situ XRD in a hydrogen-rich environment.

The effect of titanium doping on the structure and phase change characteristics of Sb4Te

As a growth-dominated phase change material, Sb4Te (ST) has fast crystallization speed while thermal stability is very poor, which makes it unsuitable for application in phase change random access memory (PCRAM). After doping Ti, the crystallization temperature is greatly improved to 210.33 °C, which is much higher than that of conventional Ge2Sb2Te5 (∼150 °C), and the melting point is reduced to 540.27 °C. In addition, grain size of crystalline Ti-doped Sb4Te (TST) film is significantly decreased to nanoscale. Ti atom is believed to occupy the lattice site of Sb atom in TST. With good thermal stability, TST-based PCRAM cell also has fast crystallization rate of 6 ns. Furthermore, the energy consumption is also lower than that of Ge2Sb2Te5-based one. Endurance of exceeding 2E5 cycles is obtained with a resistance ratio of one order of magnitude. Therefore, Ti doping seems to be a good way to solve the contradiction between thermal stability and fast crystallization speed of Sb-Te alloys.

Mechanisms of helium porosity formation in vanadium alloys as a function of the chemical composition

Transmission electron microscopy is used to study the effect of doping vanadium with titanium and iron on the formation of helium porosity and gas swelling with ionic embedding of helium at 650°C. It is found that large facetted pores larger than 20 nm form in pure vanadium and vanadium exhibits the largest gas swelling. Doping with any amount of titanium (from 0.1 to 10%) and iron (from 1 to 10%) considerably decreases helium swelling. The titanium concentration has almost no effect on the density of the bubbles. The effect of titanium doping of vanadium on the porosity parameters and swelling is of a nonmonotonic character; in the case of iron doping of vanadium the bubble density increases and the bubble size increases monotonically and swelling occurs with increasing iron concentration. The minimum sizes of the bubbles and swelling are observed in alloy with the maximum titanium content V–10%Ti and the structural alloy V–4%Ti–Cr.

Influence of Mo-doping on the magnetic properties of V 2O 3

The magnetic study of new Mo-doped vanadium sesquioxides (V 1− x Mo x ) 2− δ O 3 revealed two unexpected behaviours. On the one hand, the measured effective magnetic moment in the paramagnetic state at room temperature exhibits a peculiar variation against Mo-doping: first it increases for the lower doping rates ( x⩽5% with a metal/insulator transition), then decreases for purely metallic compositions ( x>5%). This could be explained by the existence of a spin–orbit coupling between cations. On the other hand, a very weak ferromagnetic component has been evidenced in addition to the mainly antiferromagnetic behaviour. This ferromagnetism is correlated to the partial oxidation of the samples in air at room temperature. The magnetic structure of Mo-doped compounds is similar to that of V 2O 3, but with a small rotation of the magnetic moment as a function of doping. In contrast with the effect of titanium doping, no magnetic ordering has been observed at low temperature for the highly Mo-doped samples ( x>5%), which remain metallic over the whole thermal range.

WO 3 and WTiO thin-film gas sensors prepared by sol–gel dip-coating

The WO 3 and WTiO thin-films were prepared by sol–gel dip-coating on alumina substrate using tungsten chloride, 2,4-pentanedione (PTN), ethanol and water as sources and calcined at 400 °C. The structure was characterized by XRD, Raman, SEM and TEM analyses. The effect of titanium doping on the structure was then discussed and related to the gas sensing properties. The results show that the sensitivities for detecting 10 ppm NO 2 were 82 and 1768 by WO 3 and WTiO gas sensors at 200 °C, respectively. The huge increase in sensitivity by adding titanium ion arose from the grain size reduction of the films and the doping effect on Debye length. The improved sensitivity, recovery, and reliability suggest that WO 3 and WTiO thin-films prepared by sol–gel dip-coating can be used for NO 2 gas sensing.

The effect of titanium doping on the high-temperature rhombohedral twinning of sapphire

C-axis compressive strengths of pure and titanium-doped sapphire were measured at 600°C in air. Single crystal sapphire was doped with both titanium (3+) and titanium (4+) ions from mixtures initially containing 0.05% wt. to 0.25% wt. Ti2O3 in Al2O3. It was shown that both valence state and concentration of titanium were important in slowing down twin boundary movement under c-axis compression. Titanium (4+) doping did not adversely affect the thermal conductivity and infrared optical properties of sapphire.

Effect of titanium-doping on the properties of vanadium antimonate catalysts

Catalysts of nominal compositions VSb 1− x Ti x O 4, with x = 0, 0.1, 0.2 and 0.4, were prepared by solid state reaction of vanadium(V) oxide, antimony(III) oxide and titanium(IV) oxide mixtures. Their structural and catalytic properties were studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature programmed reduction (TPR) and catalytic heterogeneous oxidation of toluene to benzaldehyde. The samples with 10% ( x = 0.1) and 20% ( x = 0.2) of titanium present the highest activity and selectivity to benzaldehyde under the operating conditions used in this work. When the titanium content is 40% ( x = 0.4), the activity level drops strongly below the level found for the undoped vanadium antimonate. X-ray patterns show the presence of vanadium(V) oxide as a separate phase in this sample, and this is probably the cause of the low catalytic performance. TPR results show that the replacement of antimony by titanium changes the oxidation-reduction properties of the vanadium antimonate phase. In the samples with titanium content up to 20%, there seems to be a direct relationship between the selectivity and the separation of the reduction temperatures of both reduction peaks of the TPR profile: the larger the separation, the higher is the selectivity to benzaldehyde. All the samples with x = 0, 0.1 and 0.2 show surface antimony excess despite being prepared from stoichiometric mixtures of nominal V/Sb ratios larger than or equal to 1.

Defect Models for Sintering and Densification of Al2O3: Ti and Al2O3: Zr

A defect model proposed to explain the effect of titanium doping on the rate of sintering of Al/sub 2/O/sub 3/ is revised to fit the oxidizing conditions of the experiments. The model accounts for the observed change in sintering rate by a change from rate limitation by ions to rate limitation by electrons, but requires the presence of an unusually large concentration of acceptor impurities in the material. Models similar to the ones originally proposed account for the rate of densification of Al/sub 2/O/sub 3/:Zr by hot-pressing in vacuo, provided it is extended by including electronics defects.