Assisted Deposition Research Articles

Plasmonic enhancement in deep ultraviolet photoresponse of hexagonal boron nitride thin films

Deep-ultraviolet (DUV) photodetectors based on hexagonal boron nitride (h-BN) have demonstrated great potentials for various commercial and military applications; however, to date, most studies show that the h-BN photodetectors suffer from poor performance, such as low responsivity and large dark current. Herein, we report the dramatic enhancement of photoresponse in the DUV region of a h-BN device coupled with plasmonic nanostructures of either h-BN nanosheets (BNNSs) or Au nanoparticles (NPs). Large-area h-BN thin films that have been directly grown on quartz substrates using the ion beam assistant deposition method exhibit a uniform thickness of ∼200 nm, an ultrawide bandgap (∼ 6 eV), and an excellent light transparency in the visible region. Based on the vertical charge transfer integrated with plasmonic nanoarrays, the photocurrent of the h-BN device can be greatly enhanced by up to about 7–9 times under the illumination of 205 nm by showing a cutoff wavelength at ∼220 nm. Owing to the retained low dark current and large photo-gain induced by localized plasmonic resonances, this hybrid photodetector exhibits 32- and 57-fold improvement in responsivity at a 205 nm wavelength by BNNSs and Au NPs, respectively. This work demonstrates plasmonic enhancement on optoelectronic properties of h-BN based on not only metallic but also semiconducting nanostructures and provides alternative pathways for the development of low-cost, large-area, high-performance, DUV photodetectors for various optoelectronic devices and security applications.

Reunderstanding the Reaction Mechanism of Aqueous Zn-Mn Batteries with Sulfate Electrolytes: Role of the Zinc Sulfate Hydroxide.

Rechargeable aqueous Zn-Mn batteries have garnered extensive attention for next-generation high-safety energy storage. However, the charge-storage chemistry of Zn-Mn batteries remains controversial. Prevailing mechanisms include conversion reaction and cation (de)intercalation in mild acid or neutral electrolytes, and a MnO2 /Mn2+ dissolution-deposition reaction in strong acidic electrolytes. Herein, a Zn4 SO4 ·(OH)6 ·xH2 O (ZSH)-assisted deposition-dissolution model is proposed to elucidate the reaction mechanism and capacity origin in Zn-Mn batteries based on mild acidic sulfate electrolytes. In this new model, the reversible capacity originates from a reversible conversion reaction between ZSH and Znx MnO(OH)2 nanosheets in which the MnO2 initiates the formation of ZSH but contributes negligibly to the apparent capacity. The role of ZSH in this new model is confirmed by a series of operando characterizations and by constructing Zn batteries using other cathode materials (including ZSH, ZnO, MgO, and CaO). This research may refresh the understanding of the most promising Zn-Mn batteries and guide the design of high-capacity aqueous Zn batteries.

Correlation between electrical, galvanomagnetic and magnetic properties of nanocrystalline iron films obtained by ion assisted deposition

Here we present the measurements of the temperature dependence of resistance, transverse and longitudinal magnetoresistance (MR) in nanocrystalline iron films in the temperature range 2-300 K and the sweep of the magnetic field up to 8 T. Thin nanocrystalline films of α-iron phase with 80 nm thickness were obtained by ion-beam assisted deposition on a silicon substrate. In addition to the shape anisotropy, the obtained iron films exhibited perpendicular magnetic anisotropy (PMA), which disappeared after annealing the films at a temperature of 450oC in a vacuum. The effect of PMA on the sign and magnitude of the MR of iron films, as well as on the magnetic field dependences of the magnetoresistive effect, recorded at different orientations of the external magnetic field with respect to the film plane and current direction, is experimentally shown. The results obtained are discussed in the framework of modern views on the processes of charge transfer in a weakly disordered ferromagnetic films with different magnetic anisotropy and domain structure when a weak (less than the saturation field of magnetization) or strong (higher than the saturation field) external magnetic field is applied. Keywords: nanocrystalline iron films, perpendicular magnetic anisotropy, magnetoresistance, anisotropic magnetoresistance, magnon magnetoresistance, percolation, weak localization.

Lithium wall conditioning techniques in ADITYA-U tokamak for impurity and fuel control

In fusion devices, various techniques are employed for coating the plasma facing components (PFCs) including the vessel wall with low-Z material like lithium, boron, and silicon in order to enhance the plasma parameters and control. In ADITYA-Upgrade tokamak, different techniques of lithium wall conditioning are developed and implemented to obtain uniform and sustainable coating of Li on PFCs and the vessel wall. In this paper, two techniques used to generate Li from the source are reported. In one of the technique, a heated (fixed temperature of ∼120 °C) Li-rod is placed inside the hydrogen glow discharge cleaning (H-GDC) plasma and the sputtered Li by hydrogen (H) ions and atoms coats the wall and periphery. In the second technique, the Li is vapourized using a high-temperature Li-evaporator and released into the H-GDC plasma for uniform coating of Li on the PFCs and vessel. Significantly enhanced plasma parameters are obtained after Li coating by both techniques, with the evaporated Li performed better than the Li rod case. With the Li coating obtained with evaporated Li at 600 °C (550 mg Li) with H-GDC, the Li wall conditioning has been observed to be sustaining for in a larger number of plasma discharges in comparison to non-H-GDC assisted Li deposition. As the melting temperature of lithium hydride (LiH) is much higher (688.7 °C) than that of lithium (180.5 °C), this enhance the longer Li-coating lifetime relatively due to the formation of Li–H molecules on the vessel wall and PFCs. In ADITYA-U the carbon impurity and hydrogen recycling, due to relatively high surface area of graphite PFCs as well as their proximity to the plasma, limits the plasma performance and effective controls. Hence, H-GDC, H-GDC with Li-rod sputtering or Li evaporation, helium-GDC, argon–hydrogen mixtures-GDC in particular sequence are carried out to obtain better plasma discharges. The Li coating techniques and their effect on tokamak plasma discharges of ADITYA-U are discussed in this paper.

In Situ BSA (Bovine Serum Albumin) Assisted Electroless Plating Method with Superior Adhesion Property

AbstractThe authors report a technique that can deposit metal micro/nano structures irrespective of the type of polymer substrate to obtain electrical conductivity of substrate with in situ solution process. Existing electronic products are made on Si‐based substrates, but as newly developed markets such as wearable devices are created, there is a need to manufacture electronic devices on organic‐based substrates. In order to meet the needs of this market, studies of fabricating a conducting layer on an organic based substrate are reported, techniques using interfacial layer materials that require a complex synthesis process. Here, BSA (bovine serum albumin) assisted metal deposition technique with simple, and excellent adhesion property of conducting layer, is reported. The chemical principle that BSA activates the catalyst ion of electroless plating is investigated, and the principle of increasing adhesion by cross‐linking the catalyst nanoparticles formed in this way is also investigated. In addition, electrical/mechanical characteristics are compared with previous studies, and it is proved that it is a durable and robust technology applicable to flexible electronics.

Highly sensitive and stretchable fiber strain sensors empowered by synergetic conductive network of silver nanoparticles and carbon nanotubes

Nowadays the demand for flexible strain sensors is booming for human-centered wearable applications, yet it is still challenging to achieve a high sensitivity at large stretchability of human motions (∼100%). Herein, carbon nanotubes (CNTs) and silver nanoparticles (AgNPs) layers were consecutively deposited on stretchable polyurethane (PU) fiber by ultrasonication and polydopamine (PD) assisted chemical deposition, to achieve a fiber sensor with both high sensitivity and stretchability. Specially, the crack mechanism dominated AgNPs offer low initial resistance and generation of abundant cracks under strain, while slippage mechanism dominated CNTs guarantee the integrity of conductive path at large strain. The as-prepared PU/CNTs/PD/AgNPs sensor achieves far better sensing performance than the conventional PU/CNTs sensor, in terms of high sensitivity (gauge factor of up to 1004.5), wide workable stretching range (150%), good stability (3000 cycles @ 150%) and fast response (53 ms) and recovery (80 ms). Moreover, the PU fiber substrate also endows the strain sensor with characteristics of light-weight, small-size, and good postprocessing capability to be easily integrated into textiles by weaving, greatly facilitating the preparation of sensing textiles for wearable human motion detections. This work not only provides an efficient way to achieve trade-off between high sensitivity and large stretchability of strain sensors, but also presents huge potentials of wearable and comfortable sensing textiles for personal health monitoring.

Equiaxed microstructure formation by ultrasonic assisted laser metal deposition

Laser metal deposition (LMD) provides a unique approach for surface modification and additive manufacturing. It typically leads to the formation of columnar crystal structures and defects in metals. In this study, ultrasonic vibration was applied on LMD of 316L. Contrastive studies show that columnar microstructures were observed without ultrasound, while equiaxed crystal structures were found with ultrasonic vibration. The reasons to generate the equiaxed microstructures were discussed. The results provide a feasible method for improving the quality of additive manufactured parts.

Effects of duty ratio on properties of Ni–P–(sol)Al2O3 coating prepared by pulse-assisted chemical deposition

With the wide application of nanocomposite protective coatings in various fields, there are higher requirements for their properties. At the same time, the traditional chemical deposition and electrodeposition processes have defects with different degrees. Nanocomposite coating was prepared by pulse current assisted chemical deposition process, which has the advantages of effectively improving the chemical deposition rate and ensuring the uniformity and compactness of the deposition layer surface morphology. In this paper, the effect of different duty ratios on Ni–P-(sol)Al2O3 nanocomposite deposition was studied. The surface morphology, composition, hardness, wear resistance and elastoplastic mechanical properties of the nanocomposite coating were tested through experiments. The experimental results showed that, when the duty ratio of pulse current was 20%, the prepared Ni–P-(sol)Al2O3 nano-composite deposition layer has the best performance, and its deposition rate reached 45.99 μm/h, hardness value was 629 HV, friction coefficient was 0.395, wear-width was 126.33 μm, Young modulus was 135.216 GPa, elastic recovery ratio he/hmax reached the maximum value of 0.3976, H3/E2 reached the maximum value of 0.0505 GPa. Compared with the coatings prepared by the traditional chemical deposition process, it is found that both coatings show good compactness and uniformity. However, the pulse-assisted chemical deposition method is significantly superior to the latter in hardness and wear resistance. The deposition layer prepared by pulse-assisted chemical deposition not only has a uniform and compact surface, but also has high hardness, good toughness and optimal wear resistance.

Copper Oxide Films Deposited by Microwave Assisted Alkaline Chemical Bath

Copper oxide (CuO) films were deposited onto glass substrates by the microwave assisted chemical bath deposition method, and varying the pH of the solution. The pH range was varied from 11.0 to 13.5, and the effects on the film properties were studied. An analytical study of the precursor solution was proposed to describe and understand the chemical reaction mechanisms that take place in the chemical bath at certain pH to produce the CuO film. A series of experiments were performed by varying the parameters of the analytical model from which the CuO films were obtained. The crystalline structure of the CuO films was studied using X-ray diffraction, while the surface morphology, chemical composition, and optical band-gap energy were analyzed by scanning electron microscopy, X-ray photoelectron spectroscopy, and UV–Vis spectrophotometry, respectively. The CuO films obtained exhibited a monoclinic crystalline phase, nanostructured surface morphology, stoichiometric Cu/O ratio of 50/50 at%, and band-gap energy value of 1.2 eV.

Focused ion beam deposited carbon-platinum nanowires for cryogenic resistive thermometry

Abstract The study of thermal effects, both classical and quantum, at cryogenic temperatures requires the use of on-chip, local, high-sensitivity thermometry. Carbon-platinum composites fabricated using focused ion beam (FIB) assisted deposition form a granular structure which is shown in this study to be uniquely suited for this application. Carbon-platinum thermometers deposited using a 24 pA ion beam current have high sensitivities below 1 K, comparable to the best cryogenic thermometers. In addition, these thermometers can be accurately placed to within 10s of nanometers on the chip using a mask-free process. They also have a weak magnetic field dependence, 3% change in resistance with applied magnetic fields from 0 to 8 T. Finally, these thermometers are integrable into a variety of nanoscale devices due to the existing wide spread use of FIB.

Substituted Hydroxyapatite, Glass, and Glass-Ceramic Thin Films Deposited by Nanosecond Pulsed Laser Deposition (PLD) for Biomedical Applications: A Systematic Review

The deposition of thin films of bioactive materials is the most common approach to improve the bone bonding ability of an implant surface. With this purpose, several wet and plasma assisted deposition methods were proposed in the scientific literature. In this review, we considered films obtained by nanosecond Pulsed Laser Deposition (PLD). Since hydroxyapatite (HA) has composition and structure similar to that of the mineral component of the bone, the initial studies focused on the selection of experimental conditions that would allow the deposition of films that retain HA stoichiometry and crystallinity. However, biological apatite was found to be a poorly crystalline and multi-substituted mineral; consequently, the attention of researchers was oriented towards the deposition of substituted HA, glass (BG), and glass-ceramic (BGC) bioactive materials to exploit the biological relevance of foreign ions and crystallinity. In this work, after a description of the nanosecond ablation and film growth of ceramic materials, we reported studies on the mechanism of HA ablation and deposition, evidencing the peculiarities of PLD. The literature concerning the PLD of ion substituted HA, BG, and BGC was then reviewed and the performances of the coatings were discussed. We concluded by describing the advantages, limitations, and perspectives of PLD for biomedical applications.

A Fresh Perspective on the Thermal Stability of Thiol-Based DNA SAMs

The stability of gold surfaces modified with DNA self assembled monolayers has drawn increasing attention as the lifespan of the created sensors is an important consideration for biosensor development and applications.1–4 In this study, we investigated the thermal stability of a mixed self assembled monolayer (SAMs) composed of a short alkythiol and alkythiol modified DNA immobilized on a single crystal gold bead electrode at either open circuit potential (OCP) or by electrodeposition.5,6 Using in-situ fluorescence microscopy and electrochemical measurements, different SAMs with varied surface properties were studied, and the relative stability towards increasing temperatures was evaluated. The results show that the stability strongly depends on the preparation method, the DNA coverage and on the underlying surface crystallography.The single crystal bead electrode enabled study of a number of surface crystallographies in a self-consistent manner. For the surfaces made without potential control, the {111} regions were the least thermally stable surface and completely desorbed from the gold surface after heating to 85 °C in some cases. On the other hand, {100} is the most stable region on which SAMs can survive higher than 85 °C in buffer. The 110, 210 and 311 surfaces were also studied. The surfaces with hexagonal symmetry were less stable than those with square or rectangular symmetry. The different methods used to prepare the DNA SAM also showed significant changes in the stability. In general, SAMs made with potential assisted deposition showed higher stability than those made at OCP. This unique finding can be used to comment on typical sensor surface which are polycrystalline flat gold surfaces composed of a variety of grains and grain boundaries. These results may help to explain the irreproducible results from the DNA SAMs and such as the reported inconsistent results during DNA mismatch discrimination while the solution was heated during experiment.7 Modifying the method used to prepare the DNA SAMs and carefully controlling the composition of the gold substrate may result in significant improvements in the SAM stability. Moreover, increasing the thermal stability will result in longer term storage stability.8,9 References(1) Brittain, W. J.; Brandsetter, T.; Prucker, O.; Rühe, J. ACS Appl. Mater. Interfaces 2019, 11, 39397–39409.(2) Civit, L.; Fragoso, A.; O’Sullivan, C. K. Electrochem. commun. 2010, 12, 1045–1048.(3) Flechsig, G. U.; Peter, J.; Hartwich, G.; Wang, J.; Gründler, P. Langmuir 2005, 21, 7848–7853.(4) Ge, D.; Wang, X.; Williams, K.; Levicky, R. Langmuir 2012, 28, 8446–8455.(5) Leung, K. K.; Gaxiola, A. D.; Yu, H.-Z.; Bizzotto, D. Electrochim. Acta 2018, 261,188–197.(6) Yu, Z. L.; Casanova-Moreno, J.; Guryanov, I.; Maran, F.; Bizzotto, D. J. Am. Chem. Soc. 2015, 137, 276–288.(7) Xu, X.; Makaraviciute, A.; Kumar, S.; Wen, C.; Sjödin, M.; Abdurakhmanov, E.; Danielson, U. H.; Nyholm, L.; Zhang, Z. Anal. Chem. 2019, 91, 14697–14704.(8) McAteer, K.; Simpson, C. E.; Gibson, T. D.; Gueguen, S.; Boujtita, M.; El Murr, N. J. Mol. Catal. - B Enzym. 1999, 7, 47–56.(9) Young Choi, J.; Yang, I. M. Pharm. Anal. Acta 2016, 07.Figure 1 Figure 1

Thickness dependent growth of Ge nanoparticles in amorphous Ge/SiO2 multilayers

Amorphous Ge/SiO2 multilayers were deposited in a high vacuum by an e-gun assisted physical vapor deposition technique with continuous Ge layers either 2 or 4 nm thick, separated by 2 nm thick SiO2 layers. The aim was to explore whether annealing of these multilayers at a rather low temperature will produce Ge nanoparticles suitable for solar cell applications. All samples were characterized by scanning electron microscopy (SEM), atomic force microscopy (ARM), transmission electron microscopy (TEM) in cross-section, grazing incidence X-ray diffraction, Raman spectroscopy and grazing incidence small-angle X-ray scattering (GISAXS). It is found that annealing of very thin continuous amorphous Ge layers will lead to mostly spherical crystalline nanoparticles (NPs) of the desired size. On the other hand, from thicker Ge layers, a bimodal distribution is obtained consisting of smaller sphere-like and larger oblate spheroids, as confirmed by a calculated simulation.

Plasma-assisted deposition of indium tin oxide thin films by sublimation using an anodic vacuum arc discharge

With the anodic vacuum arc discharge as a method of physical vapor deposition (PVD) excellent properties of thin transparent conductive oxide films can be achieved, but the relations between the process parameters and the coating properties have been insufficiently described in the literature. This paper is intended to narrow this gap by investigations on indium tin oxide (ITO) thin films deposited on borosilicate glass sheets by sublimation of indium tin oxide (90:10) using an anodic vacuum arc. The arc discharge is based on a hot hollow cathode electron source and a special evaporator connected as anode. The concentration of the discharge onto the sublimating material is achieved by combining the magnetic fields of an axially symmetrical permanent magnet system and a solenoid coil. Coating rates of about 15 nm/s were achieved with an arc current of 60 A. Measurements with a planar Langmuir probe have shown that the vapor is highly ionized (about 95%). The discharge voltages are relatively low (< 60 V), so it can be assumed that the particle energies are correspondingly low. Substrate temperature (30–300 °C), oxygen gas flow (0–100 sccm) and gas pressure (0.04–0.4 Pa) were varied to study their influence on the thin film properties. Specific electrical conductivity, density and mobility of charge carriers, as well as optical properties were determined and compared with those of other PVD processes. Low specific electrical resistance of 1.8–2.0 x 10–4 Ω cm was reached at a substrate temperature of 200–300 °C independently of the pressure. The mean optical transmission (in the spectral range between 400 nm and 1100 nm) of 100 nm thick ITO films deposited at a temperature of 200 °C and at an optimized oxygen flow was determined to 84%. The roughness of the layers determined by atomic force microscopy is significantly lower than typically for magnetron sputtered films. At a pressure of 0.04 Pa, the crystalline bixbyite phase can already be detected at a coating temperature of approx. 30 °C, whereby the layer growth begins with the formation of an amorphous structure and changes to the crystalline phase with increasing layer thickness. At a temperature above 100 °C and low coating pressure the layers are completely crystalline. At a higher pressure the transition from amorphous to crystalline phase is shifted towards higher temperature. For lower oxygen flows the crystallites exhibit mainly a preferred (211) orientation. For higher oxygen flows the texture of crystallites is changed and the intensity of (440) and (622) is increased. The formation of these special crystallographic textures can probably explain the very low roughness values of the ITO layers measured by atomic force microscopy. The investigations have shown how the film properties can be adjusted by the process parameters and that the ITO sublimation using an anodic vacuum arc is suited very well for plasma assisted ITO thin film deposition.

Metal–semiconductor–metal visible photodetector based on Al-doped (Cd:Zn)S nano thin films by hydrothermal synthesis

High quality undoped and Al-doped nanocrystalline (Cd:Zn)S films [CZS and ACZS] were deposited on glass substrates by hydrothermal assisted chemical bath deposition. The Al concentration was varied from 0.5 mol.% to 2 mol.% in steps of 0.5 mol.% replacing cadmium while keeping other deposition parameters constant. XRD, SEM, and EDX were used to observe crystallinity, morphology and composition of the as prepared samples. X-ray diffraction revealed the hexagonal phase of CZS films with prominent orientation along the (002) plane. XPS analysis was used to confirm the doping concentration of Al in to CZS lattice. Repeatable photoresponse was recorded under 100 s cycle light-on and light-off conditions. 1 mol.% Al doped film being optimised as good photoconductor; a photodetector was fabricated with Ag/ACZS/Ag device structure. The ACZS photodetector exhibits similar time response, good photocurrent reproducibility and a sharp photoresponse at blue radiation with high photo-dark current ratio of 95. The device exhibits peak responsivity of 3.48 mA W−1 and detectivity of 1.26 × 1011 Jones at 470 nm. These properties suggest that the ACZS photodetector holds great potential for application in high-performance visible photodetectors, especially in the blue region.

Epitaxial growth of (AlxGa1−x)2O3 thin films on sapphire substrates by plasma assisted pulsed laser deposition

(AlxGa1−x)2O3 was grown on a-plane sapphire substrates at 500 °C by plasma assisted pulsed laser deposition (PLD) in the whole Al concentration range. The films were characterized using x-ray photoelectron spectroscopy (XPS), x-ray diffraction, atomic force microscopy, and spectrophotometry. By using XPS to measure the bandgap of the films, it was found that as the Al concentration x changes from 0.00 to 1.00, the bandgap ranges from 5.3 to 8.5 eV. The results show that plasma assisted PLD is a promising method to grow ultra-wide bandgap (AlxGa1−x)2O3 at low temperatures, which paves the way for the application of power devices and other functional devices based on (AlxGa1−x)2O3.

Simple and scalable synthesis of super-repellent multilayer nanocomposite coating on Mg alloy with mechanochemical robustness, high-temperature endurance and electric protection

Multi-functionalization is the future development direction for protective coatings on metal surface, but has not yet been explored a lot. The effective integration of multiple functions into one material remains a huge challenge. Herein, a superhydrophobic multilayer coating integrated with multidimensional organic-inorganic components is designed on magnesium alloy via one-step plasma-induced thermal field assisted crosslinking deposition (PTCD) processing followed by after-thermal modification. Hard porous MgO ceramic layer and polytetrafluoroethylene (PTFE) nano-particles work as the bottom layer skeleton and filler components separately, forming an organic-inorganic multilayer structure, in which organic nano-particles can be crosslinked and cured to form a compact polymer-like outer layer with hierarchical surface textures. Remarkably, the chemical robustness after prolonged exposure to aqua regia, strong base and simulated seawater solution profits from polymer-like nanocomposite layer uniformly and compactly across the film bulk. Moreover, the self-similar multilayer structure coating endows it attractive functions of strong mechanical robustness (>100th cyclic rotary abrasion), stable and ultra-low friction coefficient (about 0.084), high-temperature endurance, and robust self-cleaning. The organic-inorganic multilayer coating also exhibits high insulating property with breakdown voltage of 1351.8 ± 42.4 V, dielectric strength of 21.4 ± 0.7 V/µm and resistivity of 3.2 × 1010 Ω·cm. The excellent multifunction benefits from ceramic bottom skeleton, the assembly and deposition of multidimensional nano-particles, and the synergistic effect of organic inorganic components. This study paves the way for designing next generation protective coating on magnesium alloy with great potential for multifunctional applications.

A facile electroless preparation of Cu, Sn and Sb oxides coated Ti electrode for electrocatalytic degradation of organic pollutants

Electrocatalytic degradation of organic pollutants is an encouraging technology for wastewater treatment. To achieve practical application, electrode plate with cost effective fabrication, high catalytic efficiency and long service life is urgently required. This work prepared a CuO-SnO2-SbOX electrode on Ti substrate, which is achieved by ultrasonic assisted deposition of Cu layer, followed by electroless deposition of SnSb layer and finalized by calcination at 500 °C. The obtained electrode (Ti/CuO-SnO2–SbOX) exhibited high catalytic degradation activity and a high oxygen evolution potential (OEP) of 2.13 V, which is 0.4 V greater than that of the widely recognized Ti/SnO2–SbOX electrode. The oxygen evolution reaction (OER) models of active oxygen intermediate adsorption was optimized by density functional theory (DFT) calculations. The results revealed that (1) the ΔG of the OER rate-determining step was raised to 2.30 eV after Cu doping on 101 plane; (2) binding energies of the optimized surface with reactive oxygen species (ROS) were substantially decreased. Furthermore, the as-prepared electrode has a high yield of hydroxyl radical generation as evidenced by terephthalic acid detection. The potential for hydroxyl radical generation was measured to be 1.8 V at pH = 12 and 2.6 V at pH = 2.The catalytic degradation rate of methylene blue (MB) follows pseudo first order reaction kinetics, and the reaction constant K value reached 0.02964 -k/min−1, twice as much as that obtained from electrodeposition electrode (Ti/Cu/SnO2–SbOX). A degradation rate of 94.6% was achieved for MB in 100 min in the first run, and the value remained over 85% in the subsequent 10 runs. At the same conditions, the degradation rate of p-nitrophenol was over 90% in 100 min and complete mineralization was achieved in 4 h.

Transport properties and electronic structure of fluorine-doped SnO2 prepared by ultrasonic assisted mist deposition

We have investigated the relationship between the transport properties and electronic states of fluorine-doped tin dioxide (FTO) films prepared by ultrasonic assisted mist deposition. The resistivity of the films has the minimum against F/Sn ratios caused by the saturation of carrier concentration. The core-level and valence band PES spectra revealed that there were fluorine ions with two different chemical states and excess fluorine ions tended to form impurity states in band gap, which would not contribute to the conduction of the films. These spectroscopic results well explain the saturated tendency of the carrier concentration of the FTO films.

Корреляция электрических, гальваномагнитных и магнитных характеристик нанокристаллических пленок железа, полученных методом ионно-ассистированного осаждения

Here we present the measurements of the temperature dependence of resistance, transverse and longitudinal magnetoresistance (MR) in nanocrystalline iron films in the temperature range 2-300 K and the sweep of the magnetic field up to 8 T. Thin nanocrystalline films of α- iron phase with 80 nm thickness were obtained by ion-beam assisted deposition on a silicon substrate. In addition to the shape anisotropy, the obtained iron films exhibited perpendicular magnetic anisotropy (PMA), which disappeared after annealing the films at a temperature of 450 oC in a vacuum. The effect of PMA on the sign and magnitude of the MR of iron films, as well as on the magnetic field dependences of the magnetoresistive effect, recorded at different orientations of the external magnetic field with respect to the film plane and current direction, is experimentally shown. The results obtained are discussed in the framework of modern views on the processes of charge transfer in a weakly disordered ferromagnetic films with different magnetic anisotropy and domain structure when a weak (less than the saturation field of magnetization) or strong (higher than the saturation field) external magnetic field is applied.