Anatase Phase Of TiO2 Research Articles

Photoactivity Enhancement of TiO2 Nanoparticle-decorated ZnO as a Photocatalyst in Methylene Blue Degradation

Zinc Oxide (ZnO) and Titanium Dioxide (TiO2) are metal oxides that are commonly used as photocatalysts material due to photoactivity characteristics. ZnO has a better reduction potential, and high electron mobility, but has a lower contact surface area than TiO2. On the other side, TiO2 has a better photoactivity to degrade pollutants referring to high surface area but has lower electron mobility compared to that ZnO. The combination of these two metal oxides is estimated can produce a better photocatalytic activity due to the advantages of each characteristic. Therefore, in this research, the ZnO-TiO2 (1:1) was prepared and investigated. ZnO nanoparticle was synthesized by the sol-gel method using zinc acetate dihydrate as a precursor, before calcining process, anatase TiO2 powder was added to form the composite. Structural, morphological, and optical characteristics of composite powders were analyzed by using XRD, TEM, UV-Vis Spectroscopy, and PL Spectroscopy. The concentration degradation of methylene blue in a solution containing composite material was observed to determine the photocatalytic activity under UV light irradiation for 30 minutes. The XRD spectrum shows the anatase phase of TiO2 and hexagonal wurtzite of ZnO crystal structure. Based on TEM imaging ZnO nanoparticles were attaching to TiO2 surfaces estimated due to van der walls bond. The ZnO/TiO2 shows a better photoactivity up to 20 minutes reaction with a higher degradation constant rate that indicates faster methylene blue degradation.

Synthesis and evaluation of photocatalytic properties of Na–TiO2/Sr4All4O25:Eu,Dy phosphor composites

Sub-micron Sr4Al14O25:Eu,Dy phosphor particles were coated by a TiO2-sol precipitation procedure at 80 °C for 3 h. The effects of Na/H2O2 additives on TiO2 precipitation and stability of the composites over heat treatment conditions were evaluated. The distribution of TiO2 nanoclusters on the sub-micron phosphor support changed from sparse to dense clusters with increasing Na additive. X-ray diffraction and Raman spectroscopy analyses revealed that the anatase and rutile phases dominated in the Na–TiO2/phosphor nanocomposites at 300 °C. Heat treatment at 450 °C was detrimental to the stability of TiO2 anatase phase. Ultraviolet and visible light were utilized for photocatalytic decomposition of methylene blue and toluene volatile organic components in the vicinity of the Na–TiO2/phosphor composites. Optimum photocatalytic performances were obtained in TiO2/phosphor composites with low concentration precipitation additives (1% Na and 0.23 vol% H2O2) heat-treated at 300 °C. Anatase phases and Na+ existence in TiO2/Sr4Al14O25:Eu,Dy phosphor composites improved the light sensitization and overall photocatalytic efficiencies.

High performance of magnetically separable and recyclable photocatalyst of green-synthesized CoFe2O4/TiO2 nanocomposites for degradation of methylene blue

In this study, combination of ferromagnetic and semiconductor CoFe2O4/TiO2 nanocomposites was synthesised using a green synthesis method with Moringa oleifera leaf extract to easily obtain a magnetically separated nanomaterial exhibiting high photocatalytic activity. Nanocomposites with different CoFe2O4/TiO2 molar ratios were identified using x-ray diffraction (XRD), transmission electron microscopy, X-ray fluorescence, Fourier transform infrared spectroscopy, UV–visible spectroscopy, and vibration sample magnetometer. The XRD spectrum confirmed the structure of the cubic spinel ferrite and anatase phases of CoFe2O4 and TiO2, respectively. The crystallite sizes of CoFe2O4, CoFe2O4/TiO2, and CoFe2O4/3TiO2 are 7.2 nm, 8.6 nm, and 11.1 nm, respectively. The magnetic hysteresis curve showed that CoFe2O4/TiO2 had a high saturation magnetisation of 27 emu g−1 and a coercivity of 200 Oe. The optical bandgap energy for CoFe2O4/TiO2 was in the range 3.6–3.8 eV. Photocatalytic investigations were carried out using methylene blue (MB) under UV irradiation. Our results showed an increase in MB degradation with increasing TiO2 concentration. The maximum photodegradations using nanocomposites are 60.8%, 97.7%, 98.4%, 98.5%, and 98.7% at molar ratios of 1:0, 1:1, 1:2, 1:3, and 1:4, respectively, after 20 min. The increase in MB degradation was related to the formation of internal structures between CoFe2O4 and TiO2. The magnetic nanocomposites enabled separation between the photocatalyst and final degraded solution using a permanent magnet. When the degradation was above 90%, the nanocomposites could be recycled three times.

Analysis of TihxOy Films Produced by Physical Vapor Deposition Method

For decades, partially oxidized hydrides were commonly considered as undesirably contaminated phases and were avoided by scientists. Nevertheless, more recently, it was realized that in some hydrides and oxides, partial substitution of dissimilar H− and O2− anions allows one to obtain unique optical and electrical properties that might have appealing applications in commercial products. It was determined that specific properties of so called oxyhydride materials strongly depend on the used synthesis methods; therefore, there is a great interest in exploring various variants of oxyhydride formation. In the current study, TiHxOy films were deposited by a reactive magnetron sputtering process in Ar-O2-H2 gas mixtures. Color, transparency and crystal phase composition of the films coherently reacted to the Ar:O2:H2 gas ratio. Namely, the rise in partial hydrogen pressure promoted the formation of anatase phase TiO2 structure and darkening of the films. Interestingly, this had only minimal impact on the band gap values, but had a relatively strong negative effect on the photocatalytic activity of the films. The unaccustomed results stressed the difference between the partially reduced TiO2 with a significant amount of oxygen vacancies and synthesized TiHxOy films where some O2− ions are implicitly substituted by H− ions.

Atomistic Insights of Ti-Based MXenes Thermal Decomposition and Transformation to Carbon-Supported Ti–O Phases for Energy Applications

Ti–O phases combined with carbon materials are attractive for applications in energy storage, photocatalysis, and gas sensing. The oxidation of Ti-based MXenes at high temperatures has been proposed as an effective synthesis method for carbon-supported anatase and rutile TiO2. Here, the thermal degradation and phase transformation of Ti3C2T2 (T = O or OH) under vacuum, air, and water vapor environments are investigated using reactive molecular dynamics simulations. Ti3C2(OH)2 is most stable under vacuum and water vapor, and is least stable in air. In contrast, Ti3C2O2 shows the lowest stability in air. In the air environment, anatase and rutile TiO2 phases are found regardless of the surface termination, while in water vapor, the water molecules disrupt the formation of a distinct phase. Under vacuum, we observe the formation of rock-salt TiO and present a comprehensive analysis of its transformation. The phase transformation temperatures for Ti3C2O2 are 700, 600, and 700 K for vacuum, air, and water vapor environments, respectively. Ti3C2(OH)2 showed phase stability up to 1100, 600, and 900 K under vacuum, air, and water vapor environments, respectively. Our comprehensive atomistic analysis provides detailed descriptions of the thermal degradation process and phase transformation of Ti3C2T2, which helps to understand the nanoscale aspects of the experimental work.

Highly efficient visible light photoelectrochemical degradation of ciprofloxacin and azo dyes by novel TiO2/AgBiS2 photoelectrocatalyst

Nanocomposites have proven to own outstanding visible light photoelectrochemical characteristics. Ternary chalcogenides (TC), with narrow bandgaps and efficient visible light absorption, are regarded as excellent components in forming nanocomposites with classic semiconductors such as TiO2. In the current study, TiO2/AgBiS2 binary nanocomposite was synthesized via the hydrothermal method and was successfully deposited on FTO via facile and efficient EPD technique. The XRD results showed the formation of cubic phase AgBiS2 with coral-shaped structures over the TiO2 anatase phase. The FESEM and mapping results illustrate successful formation of the binary nanocomposite. The UV-DRS for the nanocomposite confirms enhancement in visible light absorption and a decrease in bandgaps calculated through Tauc's equation due to the junction formation. The synthesized photoelectrode was electrochemically characterized by the EIS, LSV, and photocurrent measurements. To further study the PEC application of the material, photoelectrocatalytic degradation of CIP and MB was studied. The nanocomposite illustrated more than 65% degradation for CIP in 45 min, which considering the small amount of deposited material on the electrode, is considered an outstanding achievement. The scavenging experiments are used to propose a photoelectrocatalytic mechanism.

Enhancement of structural, linear and non-linear optical properties of Ti1−xCa2xO2 solid solutions

Structural and morphological analyses of the Ti1−xCa2xO2 solid solutions and their complete linear and non-linear optical properties were investigated. Ti1−xCa2xO2 (0≤ x ≤0.5) powders were successfully synthesized via solid-state reaction route. The XRD patterns confirmed that the pure and doped samples exhibited anatase TiO2 phase. The crystallite size of TiO2 decreased to 82 nm after Ca doping. Furthermore, the dislocation density and lattice deformation are increased with increasing calcium concentration. SEM analysis revealed that Ti1−xCa2xO2 (0≤ x ≤0.5) powders have a granular structure and with doping, atom aggregations take on softer shapes. Energy dispersive x-ray Analysis (EDX) showed the appropriate composition for the ions depicted in the structure. Using spectrophotometric data, linear and non-linear optical parameters were obtained and associated with the Ca content. The band gap of TiO2 has shifted from 3.11 to 2.8 eV with dopant concentration. As the percentage of Ca increased, the dielectric constant and optical conductivity also increased. The dispersion energy, plasma frequency, non-linear refractive index and Sellmeier’s parameters were also calculated and discussed with respect to Ca doping. The optical results obtained revealed the potential of the Ti1−xCa2xO2 (0≤ x ≤0.5) samples for optical and optoelectronic applications.

Highly Sensitive, Robust, and Recyclable TiO2/AgNP Substrate for SERS Detection.

Label-free biosensors provide an important platform for detecting chemical and biological substances without needing extra labeling agents. Unlike surface-based techniques such as surface plasmon resonance (SPR), interference, and ellipsometry, surface-enhanced Raman spectroscopy (SERS) possesses the advantage of monitoring analytes both on surfaces and in solutions. Increasing the SERS enhancement is crucial to preparing high-quality substrates without quickly losing their stability, sensitivity, and repeatability. However, fabrication methods based on wet chemistry, nanoimprint lithography, spark discharge, and laser ablation have drawbacks of waste of time, complicated processes, or nonreproducibility in surface topography. This study reports the preparation of recyclable TiO2/Ag nanoparticle (AgNP) substrates by using simple arc ion plating and direct-current (dc) magnetron sputtering technologies. The deposited anatase-phased TiO2 ensured the photocatalytic degradation of analytes. By measuring the Raman spectra of rhodamine 6G (R6G) in titrated concentrations, a limit of detection (LOD) of 10−8 M and a SERS enhancement factor (EF) of 1.01 × 109 were attained. Self-cleaning was performed via UV irradiation, and recyclability was achieved after at least five cycles of detection and degradation. The proposed TiO2/AgNP substrates have the potential to serve as eco-friendly SERS enhancers for label-free detection of various chemical and biological substances.

Effect of Transition Metal (Fe, Co) Ion Doping on TiO2 Nano Particles.

Keywords: Growth from solution, Nanomaterials, Oxides, Photocatalytic, Sol-Gel method, DMS. . we report the growth of [Fe, Co]xTiO2 (x=0.01, 0.02 & 0.04) Nano quantum dots prepared by Sol-Gel technique, followed by freeze-drying treatment at -30°C temperature for 12hrs. The obtained Gel was thermally treated at different temperature like 200,400,600, 800°C. The crystalline size of 4 to 40 nm is achieved. X-ray diffraction pattern of samples show anatase phases of TiO2, up to 600°C. At 800°C, the phase is Rutile. Figure 1 shows the XRD patterns acquired from different samples heated at different temperatures. The diffraction peak at 25.22°, 25.49°and 25.6° observed from the XRD pattern of the Fe, Co doped TiO2 shows that the main crystal phase is anatase, and the peak at 27.47° indicates the presence of the rutile phase. All the peaks in the XRD patterns of the sample calcined at 200°C, 400°C and 600°C of TM doped TiO2 can be designated to the anatase phase (most active phase) without any indication of other crystalline phases such as rutile or brookite . As a variant valence metal cation, Fe, Co ions can react with Ti4+ on the surface of TiO2, and Ti4+ is reduced to Ti3+ which inhibits the transformation of anatase to rutile [1]. It leads to the reduction in the oxygen vacancies on the TiO2 surface and suppresses the crystallization of other phases by adsorbing onto the surface of the TiO2 particles [2]. The photocatalytic degradation of formaldehyde has been successfully demonstrated using a 250 V UV lamp with TM doped TiO2 nano powder in a specific experimental setup. The degradation rate increases linearly with dopant content increases. This indicates that the photocatalytic reaction in this experiment was effected by dopant concentration. The results obtained in this research contribute to the understanding of binary doped transition metal ions in TiO2 nanoparticles can lead the efforts of enhancing their environmental application. Study of Magnatic proprty has been carried out by using VSM. The magnetic susceptibility of the Fe, Co doped TiO2 nanopowder increases with increase in doping concentration. Fe, Co doped TiO2 exhibits ferromagnetism at room temperature. Figure 1

Fretting wear properties and microstructure evolution in micro-arc oxidation bioceramic coating pretreated using laser remelting

To improve fretting wear resistance, bio-ceramic coatings were successfully fabricated on TC6 alloy substrates using a combination of laser remelting (LRM) and micro-arc oxidation (MAO). The surface morphology, composition, and residual stress distribution of the coatings were characterized using scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, ultra-deep field three-dimensional microscopy, and X-ray stress analysis. The influence of LRM pretreatment on the fretting wear behaviour of MAO bioceramic coatings was investigated. The LRM pre-treatment did not change the phase composition of the MAO coatings, which were all composed of Al2TiO5, rutile TiO2, and anatase TiO2 phases. However, increasing the content of the rutile TiO2 phase from 68 to 89% improved the uniformity and density of the coatings and decreased the porosity by 2.8%. The fretting wear test results showed that the LRM pretreated MAO coating exhibited the best performance against fretting wear in a simulated body fluid environment. In this case, the fretting wear mechanism was attributed to slight delamination and fatigue wear.

Examination of the doping effects of samarium (Sm3+) and zirconium (Zr4+) on the photocatalytic activity of TiO2 nanofibers

Pure and samarium (Sm3+) - or zirconium (Zr4+)-doped TiO2 nanofibers were synthesized by electrospinning method followed by calcination at 500 °C for 1 h. As-spun fibers were smooth, straight and continuous, whilst EDS analysis confirmed the fiber composition and incorporation of dopants in the fibers. Doping with Sm3+ and Zr4+ greatly inhibited the phase transformation of anatase to rutile, by surrounding of Sm3+ ions through formation of Ti-O-Sm bonds and by replacement of Ti4+ ions with larger Zr4+ ions. This was confirmed by HRTEM and SAED analysis. The size of nanofibers was determined to be 133 nm, 175 nm and 155 nm for pure, (0.5%)Sm3+:TiO2 and (1%)Zr4+:TiO2, respectively. After calcination, TiO2 crystal lattice with interplanar spacing of 0.353 nm of (101) crystal plane was not significantly disturbed by Sm doping whilst crystal lattice spacing of 0.357 nm of (101) planes of anatase phase in case TiO2:1.0%Zr4+, significantly differs from the value of pure TiO2 (0.352 nm), thus implying that Zr was doped into substitutional sites of the TiO2 lattice. The indirect band gaps were calculated to be in the range 3.07–3.24 eV. TiO2:0.5%Sm3+ and TiO2:1.0%Zr4+ exhibited higher specific surface area, of 47.1 and 59.4 m2/g, respectively, than pure TiO2 fibers (19.7 m2/g). Effects of Sm3+ and Zr4+ dopant content on the photodegradation efficiency of methylene blue (MB) were studied. TiO2:0.5%Sm3+ and TiO2:1.0%Zr4+ nanofibers have shown the highest photocatalytic activity of 97% and 98% with constant rates 0.01768 min−1 and 0.01939 min−1, respectively, within180 min irradiation under visible light.

Investigation of the Effect of Different Synthesis Methods on the Photocatalytic Activity of TiO2: Comparison of Rutile and Anatase TiO2

In this study, the effect of the synthesis method (solid state, sol-gel and hydrothermal) on the photocatalytic activity of the anatase and rutile phases of TiO2 was evaluated. As a result of XRD, FESEM and BET analysis of pure phase TiO2 powders in anatase and rutile phases, the changes in particle structures, surface areas and morphologies were examined and the differences in both synthesis method and phase structures were evaluated with Photodegradation experiments. The results of the X-ray diffraction (XRD) analysis showed that the TiO2 compound synthesized in the anatase phase and by the synthesized hydrothermal method exhibited a much smaller crystal size than the other synthesis methods and the rutile phase. Surface morphology examinations of the samples were made with scanning electron microscopy (FESEM), particle sizes were determined in the range of 90-200 nm, and their surface areas were examined by Brunauer–Emmett–Teller (BET) analysis.The adsorption-desorption isotherms shown also support the XRD data of the highest surface area.The photocatalytic behavior of the compounds was investigated using methylene blue degradation.As a result of all the syntheses and characterization studies, it has been shown that TiO2 obtained by hydrothermal method exhibits the best photocatalytic activity.

Physicochemical properties and photocatalytic activity in the 2-propanol degradation of transition metals (Zr, Zn or Nb) doped TiO2 solids

For improving the photocatalytic activity of titania under UV or sunlight (SL) irradiations in the gaseous phase degradation of 2-propanol, M−TiO2 catalysts were synthesized by the sol–gel method (with M = Zr, Zn and Nb) and characterized by various techniques. It was found that the solids show only the diffraction peaks of TiO2 anatase phase with high surface area and porosity. The type of transition metal affects the physicochemical properties and photocatalytic activity of M−TiO2 catalysts which were found more active and more selective to CO2 using UV illumination. Only the Nb-TiO2 solid was less active than TiO2. However, 0.5 % Zr-TiO2 sample was the most efficient catalyst for the photodegradation of 2-propanol with 58 % as 2-propanol maximum conversion to CO2 (54.4 %) and acetone (45.6 %) under UV. This is attributed to its high surface area and porosity, reduced particle size and low band gap energy.

Characterization and photocatalytic performance of hydrothermally synthesized Cu-doped TiO2 NPs

Titanium dioxide (TiO2) nanoparticles having different Cu doping concentration (0, 2.5 and 5%) are synthesized using simple hydrothermal processing. Copper doping effect in TiO2 matrix is investigated through different complimentary analytical techniques. XRD and Raman confirm the anatase phase of TiO2. TEM and XRD depict that particle size is altered with doping without any change in morphology. UV–Vis study reveals decrement in the band gap of TiO2 NPs on introducing Cu content. Photoluminescence shows emission peaks that are red shifted and arise due to oxygen and titanium vacancies appearing after Cu2+ ions doping. The photo-induced catalytic behaviour of Cu-doped TiO2 NPs is estimated through decomposition of methylene blue dye solution. The results depict that Cu2+ ions incorporation in TiO2 NPs lead to higher catalytic activity. The present work established that Cu-doped TiO2 NPs are promising materials employable as photocatalysts for various environmental applications.

Co, Cu, Fe, and Ni Deposited over TiO2 and Their Photocatalytic Activity in the Degradation of 2,4-Dichlorophenol and 2,4-Dichlorophenoxyacetic Acid

Pure TiO2 synthesized by the sol-gel method and subsequently deposited at 5% by weight with Co, Cu, Fe, and Ni ions by the deposition–precipitation method was studied as photocatalysts. The nanomaterials were analyzed by SEM, TEM, UV-Vis DRS, DRX, Physisorption N2, and XPS. The SEM and TEM images present a semi-spherical shape with small agglomerations of particles and average size between 63 and 65 nm. UV-Vis results show that a reduction below 3.2 eV exhibits a redshift displacement and increment in the optical absorption of the nanoparticles promoting the absorption in the UV-visible region. XRD spectra and analysis SAED suggest the characteristic anatase phase in TiO2 and deposited materials according to JCPDS 21-1272. The specific surface area was calculated and the nanomaterial Ni/TiO2 (21.3 m2 g−1) presents a slight increment when comparing to TiO2 (20.37 m2g−1). The information generated by the XPS spectra present the deposition of metallic ions on the support and the presence of different valence states for each photocatalyst. The photocatalytic activity was carried out in an aqueous solution with 80 mg L−1 of 2,4-D or 2,4-DCP under UV light (285 nm) with 100 mg L−1 of each photocatalysts for 360 min. The nanomaterial that presented the best efficiency was Ni/TiO2, obtaining a degradation of 85.6% and 90.3% for 2,4-D and 2,4-DCP, respectively. Similarly, this material was the one that presented the highest mineralization, 68.3% and 86.5% for 2,4-D and 2,4-DCP, respectively. Photocatalytic reactions correspond to the pseudo-first-order Langmuir–Hinshelwood model.

La3+'s Effect on the Surface (101) of Anatase for Methylene Blue Dye Removal, a DFT Study.

Density functional theory (DFT) is a widely used method for studying matter at the quantum level. In this study, the surface (101) of TiO2 (anatase phase) was considered to develop DFT calculations and explain the effect of lanthanum ion (La3+) on the electronic properties, adsorption capacity, and photocatalytic activity of this semiconductor. Due to the presence of the La3+ ion, the bandgap energy value of La/TiO2 (2.98 eV) was lower than that obtained for TiO2 (3.21 eV). TDOS analysis demonstrated the presence of hybrid levels in La/TiO2 composed mainly of O2p and La5d orbitals. The chemical nature of the La-O bond was estimated from PDOS analysis, Bader charge analysis, and ELF function, resulting in a polar covalent type, due to the combination of covalent and ionic bonds. In general, the adsorption of the methylene blue (MB) molecule on the surface (101) of La/TiO2 was energetically more favorable than on the surface (101) of TiO2. The thermodynamic stability of doping TiO2 with lanthanum was deduced from the negative heat-segmentation values obtained. The evidence from this theoretical study supports the experimental results reported in the literature and suggests that the semiconductor La/TiO2 is a potential catalyst for applications that require sunlight.

Development of a TiO2/Sepiolite Photocatalyst for the Degradation of a Persistent Organic Pollutant in Aqueous Solution.

A clay-based TiO2 nanocomposite material was synthesized by a facile method, to investigate its structure and photocatalytic efficiency. The supported TiO2 nanoparticles were generated using a sol-gel method, and subsequently, mixed with a suspension of sepiolite. The material was recovered in powder form (Mc-80) and then calcined to properly arrange the crystal lattice of the TiO2 particles for use in heterogeneous photocatalysis (Mc-80-500). A powder X-ray diffractogram of Mc-80-500 revealed a dispersion of anatase and rutile phase TiO2 particles on the clay surface, exhibiting a size in the order of 4–8 nm. TEM images of Mc-80-500 confirmed the presence of isolated TiO2 beads on the surface of the fibrous sepiolite. The specific surface area of Mc-80-500 was larger than that of raw sepiolite and that of free TiO2 nanoparticles. Mc-80-500 was found to be more efficient in heterogeneous photocatalysis compared to other TiO2 materials based on sepiolite. Total depollution of a reactive dye (Orange G) was achieved after 1 h irradiation time, which is relatively quick compared to previous reports. The photocatalyst material can be washed with distilled water without chemical additives or calcination, and can be reused several times for photocatalysis, without loss of efficiency.

The High Impact of Solution Flow Rate on Optical Properties of TiO2 Thin Layers for Optoelectronic Applications

AbstractThe semiconductor's realization is a very significant stage of optoelectronics devices. In this work, an elaboration of the TiO2 semiconductor is made with various solution flow rates via spray pyrolysis. The structural and optical properties of pure TiO2 are investigated with several characterization techniques which include: X‐ray diffraction (XRD), Raman spectroscopy, and UV–vis spectrophotometry. The XRD of elaborated TiO2 layers exhibits nanocrystalline nature with a preferential orientation at the (101), a unique phase of anatase TiO2. The apparition of vibration modes in Raman spectra confirms the TiO2 formation with a single phase. The produced TiO2 has an optical transmission varying from 90% to 70% in the visible wavelength. The energy band gaps are 3.42, 3.32, and 3.28 eV for the TiO2 elaborated at 1, 1.5, and 2 mL min−1, respectively which prove the semiconducting properties of TiO2. All other optical parameters such as refractive index (n), extinction coefficient (k), and dielectric constant (εr, εi) vary with the variation of solution flow rate. These investigations discover that the properties of TiO2 layers can be adjusted by solution flow rate. It seems that the process of spray pyrolysis provides a facile way to control the quality of TiO2 thin layers.

Structural and morphological properties of titanium dioxide nanoparticles dopped by Boron atoms

The phase composition and morphology of boron-containing TiO2 nanoparticles obtained by the sol-gel method were investigated. The solution of titanium aqua complex [Ti (OH2)6]3+‧3Cl- was used as a precursor. Borate acid Н3ВО3 (promoter of the formation of rutile) was used as a modified reagent. A single-phase rutile TiO2 was obtained at a concentration of borate acid in the reaction mixture, which causes the formation of a 0.5В-TiO2 sample. The particles of 0.5В-TiO2 samples were in the villi-form, with a diameter of 0.8-1.2 nm, and a length of 16-24 nm.
 With an increase of the Н3ВО3 concentration in the reaction mixture, synthesized oxide materials (samples of 1.0В-TiO2 and 1.5В-TiO2) contain 70 % and 57% of anatase respectively, in addition to rutile phase. Titanium-borate monodentate molecules Ti(OH)3OB(OH)2‧2Н2О were formed during the synthesis of the 0.5B-TiO2 rutile sample. The interatomic distance of Ti-O in these particles is commensurate with the average length of the Ti-O – bond of TiO6 rutile octahedra. During the polycondensation process, the distance of the Ti-O molecule-promoter was reproduced as a pattern in the following octahedra of rutile crystals.
 Two types of titanium-borate molecules are formed in the reaction medium, during the synthesis of 1.0В-TiO2 and 1.5В-TiO2 samples. Molecules with a bidentate mononuclear structure Ті(ОН)2О2ВОН‧2Н2О in which the interatomic distance of Ti-O is commensurate with the average length of the Ti-O –bond in the anatase octahedra was formed. Therefore, titanium-borate molecules of the second type act as a promoter of the formation of the TiO2 anatase phase.

Femtosecond large-area fabrication of multi-phase titanium oxide LIPSS on thin films

The effect of the laser beam scanning velocity and overlap on the large-area fabrication of Laser-Induced Periodic Surface Structures (LIPSS), on 400 nm thickness titanium films, is investigated. The experiments were performed in ambient air with well below ablation threshold laser fluence by using a femtosecond laser at a wavelength of 1030 nm with a pulse duration of 270 fs, operating at a repetition rate of 20 kHz.For this purpose, single-line experiments were performed to study the LIPSS formation process as a function of fs-laser-beam scanning velocity. Based on these results, the fabrication of large-area LIPSS pattern was investigated by unidirectional scanning of the fs-laser beam across the sample surface using different lateral spacing. The results show the formation of LSFL and TLIPSS, with different orientation with respect to the polarization of the incident radiation. The analysis of the chemical composition, by microRaman spectroscopy, indicates the formation of a mixture of TiO2 (anatase phase) and Ti2O3 (rutile phase) for high scanning velocities and TiO2 (rutile phase) for low scanning velocities. The chemical composition, spatial period, and depth of the LIPSS show a clear dependence with the laser-beam scanning velocity and overlap.