Growth of TiO2 nanotubes by anodization of Ti-7.5Mo in NH 4F solutions

Titanium and its alloys are widely used as biomaterials due to their mechanical, chemical and biological properties. To enhance the biocompatibility of titanium alloys, various surface treatments have been proposed. In particular, the formation of titanium oxide nanotubes layers has been extensively examined. According to the literature, it is possible to induce the growth of TiO2 on the surface of titanium, employing the aqueous anodizing electrolyte. This Ti-7.5Mo alloy was anodized in glycerol electrolytes containg 0.25 wt% of NH4F, with variations in time, voltage and calcinations temperature. After anodization, the sample surfaces were analyzed with a field emission scanning electron microscopy, DRX and contact angle measurements. It was possible to observe the formation of TiO2 on the surface and these findings represent a simple surface treatment for Ti alloys that has high potential for biomedical applications. Copyright © 2013 American Scientific Publishers. All rights reserved.

Growth of nanowires of beta-NaxV2O5 by metalorganic chemical vapor deposition

Films comprised of nanowires of beta-NaxV2O5 measuring 20-200 nm in diameter and 10-30 mum in length have been prepared on glass substrates by metalorganic chemical vapor deposition using the beta-diketonate complex, vanadyl acetyl acetonate, as precursor, but without the use of either templates or catalysts. Films consisting of nanowires of monophasic beta-NaxV2O5 with a preferred orientation along (h0l) are formed only at 550 degreesC, whereas those deposited at 540 degreesC comprise a mixture of nanowires (beta-NaxV2O5) and platelets (V2O5). The films deposited at lower temperatures are less crystalline and comprise a mixture of vanadium oxide phases. From the observations that nanowires are formed only in the narrow temperature range of 540-550 degreesC, and from the critical dependence of the formation of nanowires on the balance between the CVD growth rate and the evaporation rate of the film, it is inferred that the formation of nanowires of beta-NaxV2O5 is due to chemical vapor transport.

Effect of W addition on the electrical switching of VO2 thin films

Vanadium Oxide has been a frontrunner in the field of oxide electronics because of its metal-insulator transition (MIT). The interplay of different structures of VO2 has played a crucial role in deciding the magnitude of the first order MIT. Substitution doping has been found to introduce different polymorphs of VO2. Hence the role of substitution doping in stabilizing the competing phases of VO2 in the thin film form remains underexplored. Consequently there have been reports both discounting and approving such a stabilization of competing phases in VO2. It is reported in the literature that the bandwidth of the hysteresis and transition temperature of VO2 can be tuned by substitutional doping of VO2 with W. In this work, we have adopted a novel technique called, Ultrasonic Nebulized Spray Pyrolysis of Aqueous Combustion Mixture (UNSPACM) to deposit VO2 and W- doped VO2 as thin films. XRD and Raman spectroscopy were used to investigate the role of tungsten on the structure of VO2 thin films. Morphology of the thin films was found to be consisting of globular and porous nanoparticles of size similar to 20nm. Transition temperature decreased with the addition of W. We found that for 2.0 at % W doping in VO2, the transition temperature has reduced from 68 degrees C to 25 degrees C. It is noted that W-doping in the process of reducing the transition temperature, alters the local structure and also increases room temperature carrier concentration. (c) 2016 Author(s).

Composite beta-AgVO3@V5+1.6V4+0.4O4.8 hydrogels and xerogels for catalytic applications

Comunicación (Poster) en panel del congreso: Designing New Heterogeneous Catalysts, Faraday Discussion, 4–6 April 2016. London, United Kingdom.

Hybrid permeable metal-base transistor with large common-emitter current gain and low operational voltage

We demonstrate the suitability of N,N'-diphenyl-N,N'-bis(1-naphthylphenyl)-1,1'-biphenyl-4,4'-diamine (NPB), an organic semiconductor widely used in organic light-emitting diodes (OLEDs), for high-gain, low operational voltage nanostructured vertical-architecture transistors, which operate as permeable-base transistors. By introducing vanadium oxide (V2O5) between the injecting metal and NPB layer at the transistor emitter, we reduced the emitter operational voltage.

Controllable Synthesis and Luminescence Properties of La(OH)(3) and La(OH)(3):Tb3+ Nanocrystals with Multiform Morphologies

One-dimensional La(OH)(3) nanocrystals with multiform morphologies have been successfully synthesized by a facile bydrothermal process without using any surfactant, catalyst, or template. It can be found that the pH values of the initial solutions and the alkaline sources play a crucial role in controlling the morphologies of the products. The possible formation process of the 1D samples was investigated in detail, Furthermore, the as-prepared Tb3+-doped La(OH)(3) samples show a strong green emission corresponding to D-5(4)-F-7(5) transition of the Tb3+ ions under ultraviolet or low-voltage excitation.

Uniform Ln(OH)(3) and Ln(2)O(3) (Ln = Eu, Sm) Submicrospindles: Facile Synthesis and Characterization

Monodisperse hexagonal Ln(OH)(3) (Ln = Eu, Sm) submicrospindles with uniform morphology and size have been Successfully synthesized in a large scale via a Facile aqueous solution route from the mixture of aqueous solutions or LnCl(3) and NaOH at 5 degrees C without using any surfactant or template. The as-synthesized products are characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), energy-dispersive X-ray (EDX) spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). The SEM and TEM images show that the as-formed Ln(OH)(3) samples have a spindlelike shape with an equatorial diameter of 80-200 nm and a length of 500-900 nm, which are aggregates of even smaller nanoparticles.

Self-assembled 3D flowerlike Lu2O3 and Lu2O3 : Ln(3+) (Ln = Eu, Tb, Dy, Pr, Sm, Er, Ho, Tm) microarchitectures: Ethylene glycol-mediated hydrothermal synthesis and luminescent properties

Three-dimensional flowerlike Lu2O3 and Lu2O3:Ln(3+) (Ln = Eu, Th, Dy, Pr, Sm, Er, Ho, Tm) microarchitectures have been successfully synthesized via ethylene glycol (EG)-mediated hydrothermal method followed by a subsequent heat treatment process. X-ray diffraction, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectra, thermogravimetric and differential thermal analysis, elemental analysis, inductively coupled plasma atomic absorption spectrometric analysis, ion chromatogram analysis, X-ray photoelectron spectra, scanning electron microscopy, transmission electron microscopy, photoluminescence spectra as well kinetic decays, and cathodoluminescence spectra were used to characterize the samples. Hydrothermal temperature, EG, and CH3COONa play critical roles in the formation of the lutetium oxide precursor microflowers. The reaction mechanism and the self-assembly evolution process have been proposed. The as-formed lutetium oxide precursor could transform to Lu2O3 With their original flowerlike morphology and slight shrinkage in the size after postannealing process.

Size-tailored synthesis and luminescent properties of one-dimensional Gd2O3 : Eu3+ nanorods and microrods

Nearly monodisperse and well-defined one-dimensional (1D) Gd2O3:Eu3+ nanorods and microrods were successfully prepared through a large-scale and facile hydrothermal method followed by a subsequent heat treatment process, without using any catalyst or template. X-ray diffraction (XRD), thermogravimetric analysis and differential scanning calorimetry (TGA-DSC), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), photoluminescence (PL) and cathodoluminescence (CL) spectra as well as kinetic decays were used to characterize the samples. The size of the Gd2O3:Eu3+ rods could be modulated from micro- to nanoscale with the increase of pH value using ammonia solution. The as-formed product via the hydrothermal process, Gd(OH)(3):Eu3+, could transform to cubic Gd2O3:Eu3+ with the same morphology and a slight shrinking in size after a postannealing process.

Preparation of SrAl2O4:Eu2+, Dy3+ fibers by electrospinning combined with sol-gel process

One-dimensional SrAl2O4:Eu2+, Dy3+ fibers were fabricated by a simple electrospinning combined with sol-gel process. X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and photoluminescence were used to characterize the fibers. The results show that the phase structure of SrAl2O4:Eu2+, Dy3+ belongs to a monoclinic one, the composite fibers and fibers calcined at high temperature remain the original one-dimensional texture, and the SrAl2O4:Eu2+, Dy3+ was a green emission. (C) 2010 Elsevier Inc. All rights reserved.

Y2O3 : Eu3+ microspheres: Solvothermal synthesis and luminescence properties

Y2O3 : Eu3+ microspheres, with an average diameter of 3 mu m, were successfully prepared through a large-scale and facile solvothermal method followed by a subsequent heat treatment. X-ray diffraction, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectra, thermogravimetric and differential thermal analysis, inductive coupled plasma atomic absorption spectrometric analysis, scanning electron microscopy, transmission electron microscopy, photoluminescence spectra, as well kinetic decays, and cathodoluminescence spectra were used to characterize the samples. These microspheres were actually composed of randomly aggregated nanoparticles. The formation mechanisms for the Y2O3 : Eu3+ microspheres have been proposed on an isotropic growth mechanism. The Y2O3 : Eu3+ microspheres show a strong red emission corresponding to D-5(0) -> F-7(2) transition (610 nm) of Eu3+ under ultraviolet excitation (259 nm) and low-voltage electron beams excitation (1-5 kV), which have potential applications in fluorescent lamps and field emission displays.

Efficient top-emitting organic light-emitting diodes with a V2O5 modified silver anode

We fabricated efficient top-emitting organic light-emitting diodes (OLEDs) with silver (Ag) as an anode and samarium (Sm) as a semi-transparent cathode. The hole-injection barrier at the Ag anode/hole transporter interface is reduced by inserting a buffer layer of vanadium oxide (V2O5) between them. The ultraviolet photoelectron spectroscopy analysis shows that the hole-injection barrier is reduced by 0.5 eV. Both the V2O5 thickness and the organic layer thickness are optimized. The optimized device achieves a maximum current efficiency of 5.46 cd A(-1) and a power efficiency of 3.90 lm W-1, respectively.

Synthesis and characterization of Gd(OH)(3) nanobundles

Gd(OH)(3) nanobundles, which consisted of bundle-like nanorods, have been prepared through a simple and facile hydrothermal method. The crystal, purity, morphology and structural features of Gd(OH)(3) nanobundles are investigated by powder X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and energy dispersive X-ray (EDX). A possible formation mechanism of Gd(OH)(3) nanobundles is briefly discussed.

Hydrothermal syntheses and crystal structures of bimetallic cluster complexes [{Cd(phen)(2)}(2)V4O12]center dot 5H(2)O and [Ni(phen)(3)](2)[V4O12]center dot 17.5H(2)O

The hydrothermal reactions of vanadium oxide starting materials with divalent transition metal cations in the presence of nitrogen donor chelating ligands yield the bimetallic cluster complexes with the formulae [{Cd(phen(2))(2)V4O12].5H(2)O (1) and [Ni(phen)(3)](2)[V4O12] . 17.5H(2)O (2). Crystal data: C48H52Cd2N8O22V4 (1), triclinic. P (1) over bar, a = 10.3366(10), b = 11.320(3), c = 13.268(3) Angstrom, alpha = 103.888(17)degrees, beta = 92.256(15)degrees, gamma = 107.444(14)degrees, Z = 1; C72H131N12Ni2O29.5V4 (2), triclinic. P (1) over bar, a = 12.305(3), b = 13.172(6), c = 15.133(4), alpha = 79.05(3)degrees, beta = 76.09(2)degrees, gamma = 74.66(3)degrees, Z = 1. Data were collected on a Siemens P4 four-circle diffractometer at 293 K in the range 1.59degrees < theta < 26.02degrees and 2.01degrees < 0 < 25.01degrees using the omega-scan technique, respectively. The structure of 1 consists of a [V4O12](4-) cluster covalently attached to two {Cd(phen)(2)}(2+) fragments, in which the [V4O12](4-) cluster adopts a chair-like configuration. In the structure of 2, the [V4O12](4-) cluster is isolated. And the complex formed a layer structure via hydrogen bonds between the V4O12](4-) unit and crystallization water molecules.

Hydrothermal syntheses and crystal structures of new cage-like mixed-valent polyoxovanadates

Three new cage-like mixed-valent polyoxovanadates [Ni(1,10'-phen)(3)](2)[V10O26] 1, [Zn(2,2'-biPY)(3)](3)[V15O36Cl](.)3H(2)O (2) and [Co(2,2'-biPY)(3)](3)[V15O36Cl](.)3H(2)O (3) have been hydrothermally synthesized for the first time and characterized by elemental analyses, IR, EPR spectra, TG analyses and single crystal X-ray diffraction. The polyoxoanion of I exhibits an interesting empty ellipsoidal [V-2(IV) V-8(V) O-26](4-) 'host' shell, while the oxo vanadium clusters of 2 and 3 possess a spherical [V-8(IV) V-7(V) O36Cl](6-) cage with a Cl- ion encapsulated. The structure-directing role of organic templates (1,10'-phen and 2,2'-bipy) on the formation of the polyoxoanion structures is discussed.