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Density functional theory (DFT) calculations are applied to study the structure and bonding properties of groups 3-7 transition metal oxide clusters MO and ScO with 2 y − nx + q = 1, in which n is the number of metal valence electrons and q is the charge number. These clusters include MO, MO, MO, and MO ( M = Sc, Y, La); MO, MO, MO, MO, MO, and MO ( M = Ti, Zr, Hf), and so on. The obtained lowest energy structures of most of these clusters are with character of oxygen-centered radical (O). That is, the clusters contain oxygen atom(s) with the unpaired electron being localized on the 2p orbital(s). Chromium and manganese oxide clusters (except CrO) do not contain O with the adopted DFT methods. The binding energies of the radical oxygen with the clusters are also calculated. The DFT results are supported by available experimental investigations and predict that a lot of other transition metal oxide clusters including those with mixed-metals (such as TiVO and CrVO) may have high oxidative reactivity that has not been experimentally identified. The chemical structures of radical oxygen over VO/SiO and MoO/SiO catalysts are suggested and the balance between high reactivity and low concentration of the radical oxygen in condensed phase catalysis is discussed. [ABSTRACT FROM AUTHOR]

Abstract: ZnO powder photoluminescence spectra at 360–660nm modified and unmodified by ZrO2, ZrO2Y2O3 nanopowders before and after 100keV proton irradiation were investigated. It was found that introduction of nanoparticles led to ultraviolet band intensity decrease and to visual spectrum band intensity increase. Extinction of intensity occurs under the effect of protons in both bands of luminescence. Decomposition of spectra into elementary defects and analysis of their area change during modification and irradiation were carried out. [Copyright &y& Elsevier]

The crystalline nanocluster phase, in which nanoscale metal oxide clusters are self-assembled in three-dimensional periodic arrays, is described. The crystalline assembly of nanoparticles functionalized with technologically relevant ligands offers the opportunity to obtain unambiguous structural information that can be combined with theoretical calculations based on the known geometry and used to interpret spectroscopic and other information. A series of Ti/O clusters up to ∼2.0 nm in diameter have been synthesized and functionalized with the adsorbents catechol and isonicotinic acid. Whereas the isonicotinate is always adsorbed in a bridging monodentate mode, four different adsorption modes of catechol have been identified. The particles show a significantly larger variation of the Ti-O distances than observed in the known hO2 phases and exhibit both sevenfold overcoordination and five- and fourfold undercoordination of the Ti atoms. Theoretical calculations show only a moderate dependence of the catecholate net charge on the geometry of adsorption. All of the catechol-functionalized clusters have a deep-red color due to penetration of the highest occupied catechol levels into the band gap of the Ti/O particles. Spectroscopic measurements of the band gap of the Ti17 cluster are in good agreement with the theoretical values and show a blue shift of ∼0.22 eV relative to those reported for anatase nanoparticles. [ABSTRACT FROM AUTHOR]

A low cost, high throughput deposition method for films of nickel oxide (NiO) and lithium-doped nickel oxide with improved electrochromic performance is demonstrated. This method is based on ultrasonic spray deposition of aqueous-based precursor solutions in air at atmospheric pressure, which represents a significant cost savings compared to vacuum deposition methods. The resultant materials are charactenzed by X-ray diffraction, Raman spectroscopy, electron microscopy, and electrochemical mea- surements. Electrochromic performance is demonstrated with in situ optical transmission measurements during electrochemical characterization. Nickel oxide materials color anodicaily and are thereby ideally suited to be used as counter electrode for the well-known tungsten oxide (WO3) system in "smart" window applications. The coloration of nickel oxide materials is known to be slow when compared to WO3 and thereby limits the overall response time of a NiO/WO3 tandem device. The analysis of potential step response data shows that our lithium-doped nickel oxide material achieves 90% of its total coloration change in 29 s, which is comparable to reported measurements for WO3. These results significantly mitigate a potential bottleneck to the adoption of metal oxide electrochromic windows not only by demonstrating similar performance between NiO and WO3, but by achieving this result via low cost, highly scalable processing methods. [ABSTRACT FROM AUTHOR]

A new chromium (III) substituted Dawson 2-molybdo-15-tungsto- 2-phosphate K7[Cr(H2O)P2Mo2W15O61]·17H2O was synthesized by reaction of Cr(III) chloride with monolacunary Dawson molybdo-tungsto-diphosphates [P2Mo2W15O61]10- in aqueous solution. The complex has been characterized using spectroscopic and electrochemical techniques. The FT-IR spectroscopic data indicate that the polyanion overall symmetry is restored after the coordination of Cr(III). Coordination of chromium (III) is further supported by the 31P-NMR, EPR and UV-Vis electronic absorption spectroscopy results. Cyclic voltammograms of the chromium (III) complex exhibit three pairs of oxidation/reduction waves with negative ϵ0'values. These waves were assigned to two molybdenumcentered single electron redox processes and one tungsten-centered two electrons process. A positive shift of these waves when going from Dawson monolacunary complex to its Cr(III) complex. A modified Dawson structure was inferred from the results for the new chromium (III) complex, in which the chromium and molybdenum atoms are located to the same cap of the anion. [ABSTRACT FROM AUTHOR]

Abstract: Polycrystalline samples of BaSn1−x Mn x O3 with , 0.01, 0.02, 0.03, 0.04 and 0.05 were prepared by solid state reaction method. Using the powder X-ray diffraction patterns, these samples were found to be free of secondary phases. The substitution of Mn for Sn is also evidenced by the gradual disappearance of the characteristic optical band gap absorption (at 3.1 eV) and disappearance of Raman modes (centered around 835 cm−1, 1157 cm−1 and 1473 cm−1) of the host BaSnO3 with increasing Mn-content. The field dependent magnetization data collected at 300 K show that the undoped BaSnO3 is diamagnetic; upon doping Mn, the diamagnetic character of BaSnO3 diminishes and the ferromagnetic character evolves gradually with increasing Mn-content. The presence of F-centers in the samples is witnessed by the electron spin resonance (ESR) spectrum and the first order Raman spectrum of BaSnO3. At room temperature, the electrical resistivity of Mn-doped BaSnO3 is of the order of 108 Ω m. These results suggest that the ferromagnetism in these systems is due to F-center exchange interaction. The observed ferromagnetism in these samples is also supported by ESR spectra. [Copyright &y& Elsevier]

Oxidation of toluene has been investigated over supported platinum as well as over a variety metal oxide (M xO y) catalysts dispersed on high surface area γ-Al2O3. Catalysts were characterized with respect to their specific surface area (BET), metal dispersion (selective chemisorption of CO), phase composition and M xO y crystallite size (XRD) and reducibility (H2-TPR). Catalytic performance for the title reaction was investigated in the temperature range of 100–500 °C, using a feed composition consisting of 0.1% toluene in air. For Pt/M xO y catalysts, it has been found that catalytic performance depends on the nature of the support, with Pt/CeO2 being the most active catalyst at low temperatures. The intrinsic reaction rate per surface platinum atom does not depend on Pt loading (0.5–5 wt%), at least for Pt/Al2O3. Reducible metal oxides, such as ceria, are active for the title reaction and catalytic performance is improved significantly with increase of specific surface area (SSA). However, the intrinsic reaction rate per unit surface area is invariant with SSA. Dispersion of M xO y on high surface area inert supports, such as Al2O3, results in materials with relatively high catalytic activity, which seems to correlate well with the reducibility of metal oxides. Catalytic performance of M xO y/Al2O3 catalysts can be optimized by proper selection of M xO y loading. Best performing catalysts of this series include 60% MnO, 90% CeO2 and 5% CuO on Al2O3 which, under the present experimental conditions, are able to completely convert toluene toward CO2 at temperatures lower than 350 °C. Dispersion of Pt on M xO y/Al2O3 catalysts improves significantly the catalytic performance of irreducible M xO y but does not alter appreciably the activity of reducible M xO y/Al2O3 catalysts. [ABSTRACT FROM AUTHOR]

Copper electrodeposition on to a platinum substrate from an acid sulphate plating bath was investigated with and without the additive benzotriazole (BTAH). In voltammetric experiments, the deposition process is shifted to more negative potentials in the presence of BTAH than in its absence from the bath. Moreover, the current density of the deposition process was higher in the presence of this additive than in its absence. With or without the additive, copper deposition showed features of nucleation in the voltammetric curves. Scanning electronic microscopy (SEM) images showed that copper deposits laid down in the presence of BTAH, for any potential and charge density studied, were smoother than in the absence of this additive. X-ray spectra indicated that the electrodeposits produced in the absence or presence of BTAH were composed of a mixture of copper, copper oxide and platinum oxide and also indicated that in the presence of BTAH, the deposit was less crystalline than in its absence. [ABSTRACT FROM AUTHOR]

Abstract: Nanosized Zn2SnO4 (ZTO) particles were successfully synthesized by a simple hydrothermal process in water/ethylene glycol mixed solution using amines (ethylamine, n-butylamine, n-hexylamine, and n-octylamine) as mineralizer. The products were characterized by X-ray diffractions (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N2 adsorption. The results indicated that the hydrothermal conditions, such as alkaline concentration (n-butylamine), reaction temperature, solvent composition, and the kind of amines, had an important influence on the composition, crystallinity, and morphology of the product. The as-synthesized ZTO samples exhibited high activities and durabilities for photodegradation of methyl orange and the activities were mainly affected by the crystallinities of the samples. A hexagonal-shaped ZTO (H-ZTO) sample was prepared in 0.53M of n-butylamine solution at 180°C for 20h and its optical properties were characterized by UV–Vis diffuse reflectance and Photoluminescence (PL) spectra. Furthermore, the photocatalytic H2 evolution reaction from ethanol aqueous solution over H-ZTO was also investigated. [Copyright &y& Elsevier]

Abstract: Emission properties of Eu2+-doped M 3MgSi2O8 (M: Ba, Sr, Ca) are discussed in terms of the crystal structure. When Ba2+ ions account for over one third of M2+ ions, M 3MgSi2O8 crystallizes in glaserite-type trigonal structure, while Ba-free compounds crystallize in merwinite-type monoclinic structure. Under UV excitation, the Eu2+-doped glaserite-type compounds exhibit an intense blue emission assigned to 5d–4f electron transition at about 435nm, regardless of the molar ratio of Ba2+, Sr2+ and Ca2+ ions. By contrast, the Eu2+-doped merwinite-type compounds show an emission color sensitive to the ratio. A detailed analysis of the emission spectra reveals that the emission chromaticity for the Eu2+-doped M 3MgSi2O8 is composed of two emission peaks reflecting two different sites accommodating M2+ ion. [Copyright &y& Elsevier]

Abstract: Two supramolecular architectures based on polyoxometalates: [4,4′-Hbpy]2[Ni(4,4′-bpy)2(H2O)4][AsWVI 11WVO40]·4H2O (1) and [4,4′-H2bpy]2[PMoVI 9MoV 3O40]·2H3O (2) (4,4′-bpy=4,4′-bipyridine) have been prepared under hydrothermal conditions and characterized by elemental analyses, IR spectra, XPS spectra and single crystal X-ray diffraction analyses. The two compounds consist of 4,4′-bpy units with different polyoxometalates, α-Keggin [AsWVI 11WVO40]4− and pseudo-Keggin [PMoVI 9MoV 3O40]6−, respectively. No direct interactions occur among polyoxoanions in these two compounds, but the clusters together with metal-organic units or organic 4,4′-bpy units and/or water molecules construct the high-dimensional supramolecular networks through hydrogen bonds. The crystal structure analyses reveal that the organic 4,4′-bpy units have a major influence on the packing arrangements of crystals. [Copyright &y& Elsevier]

A number of materials of composition YSr2Cu2.8(XO4)0.2Oy(X = S, P, V) and others in which Y (III) was partially replaced by Sr(II) and/or Ca(II) were prepared by solid state reactions. Their unit cell parameters were determined and refined from X-ray powder data. The infrared spectra of the different tetraoxoanions incorporated in these materials were analyzed and discussed in detail. The vibrational modes of the other structural units present in these lattices were also approximately assigned in comparison with known spectral data of related materials. [ABSTRACT FROM AUTHOR]

Nine new Sb-bicapped α-Keggin-type heteropolyoxoniobates (HPNb) were synthesized under hydrothermal conditions. Among them, the As-centered HPNb was never reported before, and the two dimer compounds are the biggest isolated HPNbs at present. [ABSTRACT FROM AUTHOR]

In this letter, a Ta2O5/a-IGZO thin film transistor (TFT) was directly stacked on a crystalline-Si interdigitated back contact (IBC) photovoltaic (PV) cell to create a self-powered solar switch. The a-IGZO TFT and IBC PV cell were integrated into a single chip without an external circuit. This device exhibits switching property induced by illumination. The results show that it can be switched even under a low solar illumination of 300 W/m \(^{\mathrm {\mathbf {2}}}\) due to the low threshold voltage of the a-IGZO TFT (0.25 V). The ON/OFF current contrast ratio was measured to be \(\sim 20\) under 1-sun illumination. The fabrication process and characteristics of this device make it suitable and practicable for use as a self-powered solar switch. [ABSTRACT FROM AUTHOR]

With the advantages of low apparatus cost, better suitability for large-scale fabrication, and low thermal budget, the nonvacuum atmospheric pressure plasma jet technique and 248-nm excimer laser annealing were employed for the fabrication of indium gallium zinc oxide (InGaZnO) thin-film transistors. Devices with a 150-mJ/cm \(^{2}\) laser demonstrated excellent electrical characteristics with reduced OFF-current, including a high channel mobility of 21.2 cm \(^{2}\) /V-s, the ON-OFF current ratio of \(7\times 10^{5}\) , and a subthreshold swing of 0.48 V/decade. The improvements are attributed to the increase of oxygen vacancies in the InGaZnO channel and the reduction of traps at the ZrO2/InGaZnO interface and InGaZnO bulk. [ABSTRACT FROM AUTHOR]

In this letter, the switching mechanism of the ZrO2-based RRAM devices with the uniform and reliable reliability properties is investigated. The stability of memory window can be improved by inserting a ZnO thin film with the nonstoichiometric property between Ti top electrode and ZrO2 layer. Compared with ZrO2 film, the ZnO one can easily perform the oxidation-reduction reaction for stable endurance properties. In addition, through Gibbs free energy comparison of TiOx, ZrO2, and ZnO, we can demonstrate that the Gibbs free energy contributes to the retention performance. The device with thin ZnO layer has stable retention performance at high temperature (200 °C) due to its higher Gibbs free energy value than TiOx. [ABSTRACT FROM AUTHOR]

Abstract: The HeI/HeII photoelectron spectra of oxovanadium triethoxide (I) and oxovanadium triisopropoxide (II) are reported for the first time. We have observed significant differences in the electronic structure of the title molecules compared to their titanium analogues. Metal alkoxides (containing Mo, W, V, Nb) are precursors of polyoxometalates which are capable of supporting reversible redox reactions in the solid state. Vanadium alkoxides contain high lying occupied valence orbitals with metal character which explains the ability of their derivative polyoxometalates to become involved in reversible redox reactions. [Copyright &y& Elsevier]

In this paper, pure and Ag-doped SnO2 nanospheres were synthesized by hydrothermal method and characterized via X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), and X-ray photoelectron spectra (XPS), respectively. The gas sensing performance of the pure, 1 at.%, 3 at.%, and 5 at.% Ag-doped SnO2 sensing devices toward hydrogen (H2) were systematically evaluated. The results indicated that compared with pure SnO2 nanospheres, Ag-doped SnO2 nanospheres could not only decrease the optimum working temperature but also significantly improve H2 sensing such as higher gas response and faster response-recovery. Among all the samples, the 3 at.% Ag-doped SnO2 showed the highest response 39 to 100 μL/L H2 at 300 °C. Moreover, its gas sensing mechanism was discussed, and the results will provide reference and theoretical guidance for the development of high-performance SnO2-based H2 sensing devices. [ABSTRACT FROM AUTHOR]

Optical excitation of apical oxygen vibrations in YBa2Cu3O6+δ has been shown to enhance its c axis superconducting-phase rigidity, as evidenced by a transient blueshift of the equilibrium interbilayer Josephson plasma resonance. Surprisingly, a transient c axis plasma mode could also be induced above Tc by the same apical oxygen excitation, suggesting light activated superfluid tunneling throughout the pseudogap phase of YBa2Cu3O6+δ. However, despite the similarities between the transient plasma mode above Tc and the equilibrium Josephson plasmon, alternative explanations involving high-mobility quasiparticle transport should be considered. Here, we report an extensive study of the relaxation of the light induced plasmon into the equilibrium incoherent phase. These new experiments allow for a critical assessment of the nature of this mode. We determine that the transient plasma relaxes through a collapse of its coherence length rather than its carrier (or superfluid) density. These observations are not easily reconciled with quasiparticle interlayer transport and rather support transient superfluid tunneling as the origin of the light induced interlayer coupling in YBa2Cu3O6+δ. [ABSTRACT FROM AUTHOR]

The accumulation of iron oxides—mainly magnetite—with amyloid peptide is a key process in the development of Alzheimer’s disease (AD). However, the mechanism for biogeneration of magnetite inside the brain of someone with AD is still unclear. The iron-storing protein ferritin has been identified as the main magnetite-storing molecule. However, accumulations of magnetite in AD are not correlated with an increase in ferritin, leaving this question unresolved. Here we demonstrate the key role of amyloid peptide Aβ42, one of the main hallmarks of AD, in the generation of magnetite nanoparticles in the absence of ferritin. The capacity of amyloid peptide to bind and concentrate iron hydroxides, the basis for the formation of magnetite, benefits the spontaneous synthesis of these nanoparticles, even under unfavorable conditions for their formation. Using scanning and transmission electron microscopy, electron energy loss spectroscopy and magnetic force microscopy we characterized the capacity of amyloid peptide Aβ42 to promote magnetite formation. [ABSTRACT FROM AUTHOR]

Complex hollow tube‐in‐tube nanostructures have been fabricated for many metal oxides through a general strategy, as described by X. W. Lou, Y. Xie, et al. in their Communication on page 8643 ff. The method involves two simple steps: coating carbon nanofibers with a layer of metal glycolate and subsequent calcination in air. The unique complex tubular metal oxide structures are promising electrocatalysts for the oxygen reduction reaction and electrode materials for lithium ion batteries. [ABSTRACT FROM AUTHOR]

Molecular beam deposited zirconium dioxide (ZrO2) was assessed as high-κ gate dielectric for future GaN based devices. To compare and study electrical and structural properties, thin ZrO2 films were deposited on three different substrates, n++-c-plane GaN, p-(100) Si, and TiN. The films were fabricated by electron beam evaporation from a single stoichiometric ZrO2 target. A substrate-independent phase transition from amorphous ZrO2 to the tetragonal/cubic phase was identified by gracing incidence x-ray diffractometry. Finally, monoclinic ZrO2 emerged with increasing film thickness. As found by x-ray photoelectron spectroscopy, ZrO2 formed an abrupt interface to both GaN and TiN without intermixture. Dielectric constants in the range of 14-25 were extracted from capacitance versus voltage measurements for as-deposited ZrO2 films. The leakage currents of ZrO2 on GaN resembled their counterparts on Si as well as on TiN. [ABSTRACT FROM AUTHOR]

Thin epitaxial layers of NiInGaAs formed by solid state reaction of Ni on (100) In0.53Ga0.47As are used as metal source and drain regions for In0.53Ga0.47As metal oxide field effect transistors. Here, the authors present a structural and chemical analysis of this phase. The stoichiometry of the layer was determined as Ni2In0.53Ga0.47As. Transmission electron microscopy revealed an abrupt interface and a detailed x-ray diffraction analysis showed that the layer is of a hexagonal lattice, which grows epitaxially with the orientation relations of {100}InGaAs||{100}NiInGaAs; <011>InGaAs||[001]NiInGaAs. Only one domain can be observed in this epitaxial growth. Understanding the structure of these layers is a crucial step not only in their incorporation into InGaAs based devices but also a step toward novel devices. [ABSTRACT FROM AUTHOR]

Dielectric properties of the Zr-doped hafnium oxide high-k thin film were improved with the addition of a small amount of molybdenum. The addition of molybdenum reduced the interface density of states and the oxide charge trapping density due to the removal of some oxygen vacancies and Hf dangling bonds in the film. It also decreased the leakage current and increased the breakdown voltage because of the increase of the total film thickness. The barrier height between the gate electrode and the high-k film was lowered as a result of the formation of a dipole layer at the interface. Therefore, the addition of a small amount of metal is an effective method to improve the dielectric properties of the high-k film. [ABSTRACT FROM AUTHOR]