Ta2O5 Nanoparticles Research Articles

Optimizing dose enhancement with Ta2O5 nanoparticles for synchrotron microbeam activated radiation therapy

Microbeam Radiation Therapy (MRT) exploits tumour selectivity and normal tissue sparing with spatially fractionated kilovoltage X-ray microbeams through the dose volume effect. Experimental measurements with Ta2O5 nanoparticles (NPs) in 9L gliosarcoma treated with MRT at the Australian Synchrotron, increased the treatment efficiency. Ta2O5 NPs were observed to form shells around cell nuclei which may be the reason for their efficiency in MRT. In this article, our experimental observation of NP shell formation is the basis of a Geant4 radiation transport study to characterise dose enhancement by Ta2O5 NPs in MRT. Our study showed that NP shells enhance the physical dose depending microbeam energy and their location relative to a single microbeam. For monochromatic microbeam energies below ∼70keV, NP shells show highly localised dose enhancement due to the short range of associated secondary electrons. Low microbeam energies indicate better targeted treatment by allowing higher microbeam doses to be administered to tumours and better exploit the spatial fractionation related selectivity observed with MRT. For microbeam energies above ∼100keV, NP shells extend the physical dose enhancement due to longer-range secondary electrons. Again, with NPs selectively internalised, the local effectiveness of MRT is expected to increase in the tumour. Dose enhancement produced by the shell aggregate varied more significantly in the cell population, depending on its location, when compared to a homogeneous NP distribution. These combined simulation and experimental data provide first evidence for optimising MRT through the incorporation of newly observed Ta2O5 NP distributions within 9L cancer cells.

Thermal decomposition preparation and characterization of Ta2O5 nanoparticles with the aid of different acids and investigation of its photocatalyst application

In the current study, an attempt is made to synthesize tantalum pentoxide (Ta2O5) nanoparticles via a thermal decomposition route with the aid of tantalum salt in an aqueous solution. Besides, capping agents such as salicylic acid, sulfanilic acid, and cinnamic acid were used to investigate their effects on the morphology and particle size of Ta2O5 nanoparticles. XRD, SEM, EDS, and UV–Vis spectroscopy were employed to characterize structural, morphological, and optical properties of tantalum pentoxide nanoparticles. According to the vibrating sample magnetometer (VSM) result, Ta2O5 nanoparticles indicated a ferromagnetic behavior at room temperature. Furthermore, the photocatalytic properties of as synthesized Ta2O5 were evaluated by degradation of methyl orange (MO) as water contaminant.

Study of the effect of ceramic Ta2O5 nanoparticle distribution on cellular dose enhancement in a kilovoltage photon field

The application of nanoparticles (NPs) in radiotherapy is an increasingly attractive technique to improve clinical outcomes. The internalisation of NPs within the tumour cells enables an increased radiation dose to critical cellular structures. The purpose of this study is to investigate, by means of Geant4 simulations, the dose enhancement within a cell population irradiated with a 150kVp photon field in the presence of a varying concentration of tantalum pentoxide (Ta2O5) NP aggregates, experimentally observed to form shells within tumour cells. This scenario is compared to the more traditionally simulated homogeneous solution of NP material in water with the same weight fraction of Ta2O5, as well as to a cell population without NPs present. The production of secondary electrons is enhanced by increased photoelectric effect interactions within the high-Z material and this is examined in terms of their kinetic energy spectra and linear energy transfer (LET) with various NP distributions compared to water. Our results indicate that the shell formation scenario limits the dose enhancement at 150kVp. The underlying mechanism for this limit is discussed.

Blue and NIR emission from nanostructured Tm3+/ Yb3+ co-doped SiO2–Ta2O5 for photonic applications

This paper reports on the synthesis of Tm3+/Yb3+ co-doped SiO2–Ta2O5 nanocomposites prepared by a sol–gel route. XRD analysis revealed initial crystallization of the L-Ta2O5 structure dispersed in the silica host, which depended on lanthanide concentration. Vibrational spectroscopy showed low OH groups content, SiO2–Ta2O5 nanocomposite formation, and controlled phase separation characterized by the presence of Ta2O5 nanoparticles. Emission in the near infrared was evident and also depended on lanthanide concentration and excitation wavelength. Direct excitation on the host promoted NIR luminescence; higher intensity emerged at 980 nm, attributed to Yb3+ ions. Excitation of the Tm3+ excited levels elicited energy transfer between Tm3+ and Yb3+ ions. Excitation of the Tm3+ levels (visible range) and the host (UV) promoted emission in the S telecom band for all the samples. Excitation at 980 nm gave rise to upconversion emissions at 476 nm (blue) and 793 nm (NIR). At higher lanthanide concentration, the presence of a dominant cross-relaxation process reduced the blue emission with respect to the NIR emission. The color coordinates were similar to the coordinates of standard blue. All these luminescent properties make the synthesized materials potential candidates for photonic applications like energy converting devices, solar concentrators, and blue emitters.

Enhanced performance of dye-sensitized solar cells based on P25/Ta2O5 composite films

In this paper, novel titanium dioxide/tantalum pentoxide (P25/Ta2O5) composite films have been successfully fabricated and applied to dye-sensitized solar cells (DSSCs). Ta2O5 nanoparticles are synthesized by a simple low-temperature solvothermal method. The influence of Ta2O5 nanoparticles on photovoltaic performance of DSSCs is systematically investigated. As a result, the DSSC based on 10 wt% Ta2O5 incorporated P25 film exhibits excellent photovoltaic performance with a power conversion efficiency (PCE) as high as 5.85 %. Compared to a reference DSSC based on the pure P25 film (4.93 %), the PCE of DSSCs has been remarkably enhanced by 19 %. Such enhancement can be mainly attributed to the higher electron collection efficiency in P25/Ta2O5 composite films, which result from the suppression of the electron recombination at the photoanode/electrolyte interface.

Hydrogen peroxide electrogeneration in gas diffusion electrode nanostructured with Ta2O5

Highly efficient H2O2 electrogeneration is required in the Advanced Oxidation Process for organic wastewater treatment. However, the development of more efficient catalytic particles used in gas diffusion electrodes (GDEs) to enable the oxygen reduction reaction through two-electron transfer is still of great importance. The performance of the Ta2O5 nanoparticles on carbon black in catalyzing the ORR was evaluated using rotating ring-disk electrode. The current efficiency for H2O2 electrogeneration on Ta2O5/C catalyst is 83.2% whereas carbon black exhibits 65.3%. GDEs were constructed using carbon black either unmodified or modified with Ta2O5 nanoparticles. The modified GDE produces 27.9mgL−1 of H2O2, while the unmodified GDE generates 19.1mgL−1 of H2O2. Furthermore, the energy consumption for the H2O2 electrogeneration is lower in modified than in unmodified GDE (15.0kWh vs. 18.8kWh). The high performance of the GDE (Ta2O5/C) renders it a viable alternative cathode in the electrochemical treatment of wastewaters.

High-performance supercapacitor based on tantalum iridium oxides supported on tungsten oxide nanoplatelets

Here we report on a novel supercapacitor electrode based on IrO2–Ta2O5 nanoparticles supported on WO3 nanoplatelets. The nanoplatelets were directly grown on a W plate using a facile hydrothermal method, whereas the IrO2–Ta2O5 nanoparticles were formed via a thermal decomposition technique which can be easily scaled up. The structural, morphological, and electrochemical properties of the WO3 nanoplatelets and the formed trimetallic oxide nanocomposite have been investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), cyclic voltammetry (CV), and charging/discharging techniques. The fabricated trimetallic oxide nanocomposite exihibited rectangular cyclic voltamograms even tested at high potential scan rates, a high specific capacitance and high charging/discharging stability, promising utilization in the design of high-performance devices for energy storage.

ChemInform Abstract: Visible Light Assisted Photocatalytic Hydrogen Generation by Ta2O5/Bi2O3, TaON/Bi2O3, and Ta3N5/Bi2O3 Composites.

AbstractTa2O5/Bi2O3 core‐shell nanocomposites are prepared by adding Bi(NO3)3 to a suspension of Ta2O5 nanoparticles in BnOH (150 °C, 8 h) followed by calcination at 400 °C (≈80% yield).

Enhanced osteointegration on tantalum-implanted polyetheretherketone surface with bone-like elastic modulus

Polyetheretherketone (PEEK) possesses a similar elastic modulus as bones but yet suffers from bio-inertness and poor osteogenesis. In this work, tantalum ions are implanted energetically into PEEK by plasma immersion ion implantation (PIII) to form Ta2O5 nanoparticles in the near surface. Nanoindentation reveals that the surface elastic modulus of the Ta ion implanted PEEK is closer to that of human cortical bones. In vitro cell adhesion, alkaline phosphatase activity, collagen secretion, extracellular matrix mineralization, and real-time PCR analyses disclose enhanced adhesion, proliferation, and osteogenic differentiation of rat bone mesenchymal stem cells (bMSCs) on the Ta-PIII modified PEEK. In vivo evaluation of the cortico-cancellous rat femur model by means of micro-CT, sequential fluorescent labeling, and histological analysis after 8 weeks confirms significantly improved osteointegration. The bone-like elastic modulus and modified surface topography of the Ta-PIII modified PEEK synergistically induce osteogenic differentiation of bMSCs and the surface-modified materials have large potential in dental and orthopedic implants.

Synthesis of tantalum pentoxide hollow spheres utilizing a sacrificial templating approach

A hydrothermal route to synthesize tantalum pentoxide (Ta2O5) hollow spheres (TPHSs) using tantalum pentaethoxide (Ta(OET)5) as the oxide precursor and glucose-derived carbonaceous spheres (CSs) as the sacrificial templates have been described. The carbonaceous spheres (CSs) were first prepared by hydrothermal carbonization of glucose, then a controlled coating of the template surface by Ta2O5 nanoparticles via the hydrolyzing of tantalum pentaethoxide at ambient temperature was implemented. Subsequent removal of the interior carbonaceous cores by pyrolytic treatment through oxidation in air produces freestanding TPHSs. The obtained TPHSs were characterized by means of SEM, TEM, XRD, and IR spectroscopy.

Characterization and photocatalytic study of tantalum oxide nanoparticles prepared by the hydrolysis of tantalum oxo-ethoxide Ta8(μ3-O)2(μ-O)8(μ-OEt)6(OEt)14.

Ta8(μ3-O)2(μ-O)8(μ-OEt)6(OEt)14 (1) was obtained by the controlled hydrolysis of tantalum ethoxide Ta(OEt)5 in the presence of ammonia. Compound 1 is considered as the intermediate building block in the sol–gel polymerization of Ta(OEt)5. Further hydrolysis of compound 1 yielded nanoparticles of Ta2O5, which were characterized by various techniques such as TGA-DTA-DSC, UV–vis DRS, XRD, SEM, TEM, particle size analyzer (DLS) and the Brunauer–Emmett–Teller (BET) method. The band gap of the particles was calculated by using the Tauc plot. The photocatalytic activity of Ta2O5 nanoparticles was tested by the degradation of the organic dye rhodamine B.

The role of dissolved oxygen in the Ta(O)N-driven visible Fenton-like degradation of atrazine

The role of dissolved oxygen (DO) in a visible Fenton-like degradation of atrazine driven by Ta(O)N was examined in detail. First, Ta(O)N samples were prepared by the nitridation of Ta2O5 nanoparticles, which showed strong absorption in the range of 300–600nm. Second, the degradation of atrazine, the decomposition of H2O2, and the formation of intermediates in the visible Ta(O)N-Fenton-like system in the presence of DO were compared with those in the absence of DO. In the visible Ta(O)N–Fenton-like system, atrazine degradation was based on the attack of •OH and the atrazine degradation pathways were similar in the presence and absence of DO. Notably, however, the presence of DO suppressed atrazine degradation. An investigation into the effects of DO on the photoreduction of Fe3+ and the photodecomposition of H2O2 catalyzed by Ta(O)N showed that the presence of DO suppressed the formation of Fe2+ but did not affect the decomposition of H2O2. Therefore, the presence of DO slowed the generation of •OH. The role of DO in atrazine degradation by a visible Ta(O)N-Fenton-like system was proposed on the basis of the experimental results.

Superior H2 production by hydrophilic ultrafine Ta2O5 engineered covalently on graphene

A H2O2-mediated hydrothermal method was developed for the fabrication of hydrophilic Ta2O5/graphene composite. The composite shows a superior H2 productivity, up to 30 mmol g−1 h−1 when used as a photocatalyst for water splitting, corresponding to an apparent quantum efficiency of 33.8% at 254 nm. This superior performance is due to the hydrophilic nature of the composite and more importantly due to the ultrafine Ta2O5 nanoparticles (about 4.0 ± 1.5 nm) which are covalently bonded with the conductive graphene. The hydrophilic property of the composite is attributed to the use of H2O2 in the hydrothermal process. The ultrafine size of the Ta2O5 particles which are covalently bonded with the graphene sheets is attributed to the use of sonication in the synthesis process. Furthermore, the hydrophilic Ta2O5/Gr composite is durable, which is beneficial to long term photocatalysis. The strategy reported here provides a new approach to designing photocatalysts with superior performance for H2 production.

Multi-functional ceramic hybrid coatings on biodegradable AZ31 Mg implants: electrochemical, tribological and quantum chemical aspects for orthopaedic applications

Application of biodegradable implants has received increasing attention for the treatment of bone damage due to their low adverse effects. To achieve better biocompatibility and enhanced corrosion resistance of biodegradable implants with improved wear resistance, multifunctional coatings need to be developed. Herein, a ceramic hybrid coating has been fabricated by a plasma electrolytic oxidation (PEO) technique using Ta2O5 nanoparticle inclusion on AZ31 Mg alloy in order to attain superior corrosion, wear behavior, and surface porosity that enable improved bioactivity. X-ray diffraction analysis of PEO coatings showed that the surface coating is mainly composed of Mg3(PO4)2, MgO and Ta2O5 in different quantities based on PEO processing. Furthermore, scanning electron microscopy (SEM) analysis was employed to observe the surface of the resultant PEO hybrid coatings after and before wear tests. With Ta2O5 nanoparticles, PEO coatings showed excellent wear compared with pure PEO coatings. The efficiency of the hybrid coatings in corrosion protection was verified by the Tafel plot and electrochemical impedance spectroscopy measurements in simulated body fluid. Furthermore, in vitro cell culture studies were performed on MG-63 human cells to evaluate the biocompatibility of PEO coatings. A quantum chemical approach and force-field molecular dynamics simulation were employed to evaluate the interaction between the AZ31 Mg surface and PEO hybrid coatings. All of the observations evidently showed that the ceramic hybrid PEO coating provides improved wear and corrosion protection performance with superior biocompatibility with Ta2O5 nanoparticles, when compared to pure PEO coatings, due to its synergistic beneficial effect.

Facile surfactant-aided sol–gel synthesis of mesoporous-assembled Ta2O5 nanoparticles with enhanced photocatalytic H2 production

This work was mainly focused on the investigation of thermal treatment impact of the mesoporous-assembled Ta2O5 nanoparticles synthesized via a facile sol–gel method with the aid of a mesopore-directing surfactant on their photocatalytic hydrogen production activity from a methanol aqueous solution under UV light irradiation. The synthesized Ta2O5 nanoparticles were characterized by X-ray diffraction, N2 adsorption–desorption analysis, elemental carbon analysis, UV–vis absorbance spectroscopy, scanning electron microscopy, transmission electron microscopy, and selected-area electron diffraction. The experimental results strongly supported that the calcination temperature in the range of 500–800°C significantly affected the physicochemical properties and hydrogen production activity of the synthesized Ta2O5 nanoparticles. The synthesized Ta2O5 nanoparticles exhibited the amorphous-to-crystalline phase transformation at the calcination temperature of 650°C, at and beyond which the hydrogen production activity improvement was clearly observed. The most photocatalytically active and thermally stable Ta2O5 nanoparticle was obtained at the optimum calcination temperature of 700°C, and its hydrogen production activity was captivatingly found to be higher than that of the commercial Ta2O5 and P-25 TiO2 powders. In addition, the optimized Ta2O5 nanoparticle exhibited a very good durability for multiple reuses without significant activity loss.

Comparative Investigation of Photocatalytic Degradation of Toluene on Nitrogen Doped Ta2O5and Nb2O5Nanoparticles

Nb2O5 and Ta2O5 nanoparticles were prepared at a moderate sintering temperature of 700 °C using a solution method. Nitrogen doped Nb2O5 and Ta2O5 were obtained by ammonia gas treatment at 700 °C. The materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and UV–vis diffuse reflectance spectroscopy. All the materials were used for photocatalytic decomposition of gaseous toluene irradiated with artificial solar light and pure visible light. Most of the materials were multiple crystallites with orthorhombic and monoclinic structures. Tantalum based compounds, undoped (Ta2O5 (lab)) and nitrogen doped (Ta2O5:N (lab)), have shown much better performance than niobium based materials. Ta2O5:N (lab) decomposed gaseous toluene with a rate similar to those of Ta2O5 (lab) and Ta2O5:N (com) in the initial 60 min but at a higher rate at extended time under artificial sunlight. Ta2O5:N (lab) decomposed about 70% toluene with artificial sunlight and 30% with pure visible light (λ = 400 nm). The material also exhibited a very stable performance with artificial sunlight and pure visible light.

Lubricious silver tantalate films for extreme temperature applications

Silver tantalate was investigated as a potential lubricious material for moving assemblies in high temperature tribological applications. Three different approaches were explored for the creation of such materials on Inconel substrates: (1) powders produced using a solid state which were burnished on the surface; (2) monolithic silver tantalate thin films deposited by magnetron sputtering; and, (3) an adaptive tantalum nitride/silver nanocomposite sputter-deposited coating that forms a lubricious silver tantalate oxide on its surface when operated at elevated temperatures. Dry sliding wear tests of the coatings against Si3N4 counterfaces revealed friction coefficients in the 0.06–0.15 range at T~750°C. Reduced friction coefficients were found in nanocomposite materials that contained primarily a AgTaO3 phase with a small amount of segregated Ag phase, as suggested by structural characterization using X-ray diffraction. Furthermore, cross-sectional transmission electron microscopy techniques determined that the reduced coefficient of friction at T~750°C was primarily the result of the formation of a lubricious AgTaO3 phase that reconstructs during the wear process into a mechanically mixed layer of AgTaO3, Ta2O5, and Ag nanoparticles.

SnO2, IrO2, Ta2O5, Bi2O3, and TiO2 nanoparticle anodes: electrochemical oxidation coupled with the cathodic reduction of water to yield molecular H2

In recent years, the search for environmentally friendly alternative energy sources with reduced carbon footprints has increased. The coupling of photovoltaic power sources with advanced electrolysis systems for hydrogen production via water splitting using organic contaminants as sacrificial electron donors has been considered to a be viable alternative. In this report, we demonstrated the feasibility of a scaled-up rooftop prototype of the proposed hybrid photovoltaic-electrolysis system, which utilizes semiconductor nanoparticles coated on to metal substrates as electrodes for the generation of hydrogen coupled with the oxidation of wastewater. Application of an anodic bias of >2.0 V to bismuth-doped TiO_2 (BiO_x–TiO_2) on Ti metal anodes with a sequential under-coatings of nanoparticulate SnO_2, IrO_2, Ta_2O_5, and Bi_2O_3 results in the electrochemical degradation of a variety of organic chemical contaminants in water (i.e., rhodamine B (Rh.B), methylene blue (MB), salicylic acid, triclosan, and phenol) and actual wastewater from a chemical manufacturing plant, while at the same time, molecular hydrogen is produced at stainless steel (SS) cathodes. The kinetics of the anodic substrates oxidation is investigated as a function of the cell current (I cell), substrate concentration, and background electrolyte composition (e.g., NaCl, Na_2SO_4, or seawater). Average current efficiencies were found to be in the range of 4–22 %, while the cathodic current and energy efficiencies for hydrogen production were found to be in the range of 50–70 % and 20–40 %, respectively.

Structural and Spectroscopic Properties of Luminescent Er3+-Doped SiO2-Ta2O5 Nanocomposites

This paper reports on the preparation and structural, morphological, and luminescence properties of Er3+-doped nanocomposites based on SiO2–Ta2O5 prepared by the sol–gel method. The influence of the tantalum oxide content on the structural and spectroscopic properties was analyzed for Si/Ta molar ratios of 90:10, 80:20, 70:30, 60:40, and 50:50. The sols were kept at 60°C for formation of the xerogel, followed by annealing at 900°, 1000°, and 1100°C for 2 h for production of the nanocomposites. The densification, phase separation, and crystallization processes were monitored through vibrational spectroscopy (FTIR), X-ray diffraction, and high-resolution transmission electron microscopy. Er3+ emission in the infrared region, assigned to the 4I13/2→4I15/2 transition, was observed for all the nanocomposites. Evolution from a vitreous-like environment to a crystalline one was identified upon increasing the annealing temperature and tantalum content. According to the results obtained, the Er3+ ions are preferentially localized close to the region rich in Ta2O5 nanoparticles. The localization of Er3+ ions was shown to be dependent on the amount of tantalum. Moreover, the fact that the Er3+ ions are located close to Ta2O5 nanoparticles promotes a broadband emission with full-width at half-maximum of 90 nm around 1550 nm.

Preparation and characterizations of tantalum pentoxide (Ta2O5) nanoparticles and UV‐curable Ta2O5‐acrylic nanocomposites

AbstractTantalum pentoxide (Ta2O5) nanoparticles with the sizes in the range of 20–50 nm were prepared via a chemical route in which the oleic acid (OLEA) was adopted as the surfactant for the synthesis process. X‐ray diffraction (XRD) revealed the as‐synthesized Ta2O5 transforms from amorphous to hexagonal and orthorhombic structures at the temperatures of 700°C and 750°C, respectively, illustrating the suppression of recrystallization temperature of Ta2O5 due to the particle size reduction. UV‐curable nanocomposites containing the Ta2O5 nanoparticles and acrylic matrix were also prepared. Thermogravimetry analysis (TGA) found an about 10–20°C improvement on the 5% weight‐loss thermal decomposition temperatures (Tds). Dielectric measurement showed that the dielectric constant of nanocomposite increases with the increase in the filler loading without severe deterioration of dielectric loss. The increment of dielectric constants was ascribed to the addition of high‐dielectric inorganic fillers as well as the presence of interfacial polarization at the organic/inorganic interfaces. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010