Crystallinity and magnetic properties of electrodeposited Co nanowires in porous alumina

Crystalline Co nanowires were pulse electrodeposited into nanoporous aluminum oxide template having an ultra-thinned barrier layer. The effects of off-time between pulses and electrolyte acidity on the microstructure and magnetic properties of the nanowires were investigated. Increasing the off time between pulses increased the crystallinity and the alignment of easy axis with the wire axis. The rate of these increments was seen to depend on the electrolyte acidity and reached its maximum at pH=5.25 electrolyte acidity. Optimizing the crystallinity and crystal orientation, a coercivity value of 3320 Oe and a squareness of>90% were obtained for pure Co nanowires. A 10% increase in coercivity was found after annealing the samples.     

Electrical investigation and ultraviolet detection of ZnO nanorods encapsulated with ZnO and Fe-doped ZnO layer

Encapsulated ZnO nanorod arrays were fabricated using a two-step method; hydrothermal followed by dip-coating. Intensity of X-ray diffraction peaks of ZnO nanorod films increased by encapsulation with ZnO and Fe doped ZnO layer. Encapsulation process increased diameter of the rods in a range of 20–40 nm. The optical studies indicated that the band-gap decreased with increment of the nanorod diameter, and increased with Fe doping in the ZnO layer. The electrical resistance of the samples demonstrated a remarkable reduction due to encapsulation, especially in the sample encapsulated with Fe doped-ZnO layer. The photoresponse behavior of ZnO nanorod films was investigated under different powers of ultraviolet illumination. The photoresponsivity was improved for encapsulated nanorods as compared to bare nanorods.     

Dual behaviors of magnetic CoxFe1−x (0≤x≤1) nanowires embedded in nanoporous with different diameters

Co_xFe_1−x nanowire arrays with various diameters and different composition were fabricated by ac electrodeposition using porous alumina template. Coercivity along the easy axis reaches to a maximum at 2330 Oe, for Co_xFe_1−x nanowires containing about 40 at% Co. The crystalline structure of the nanowires was concentration-independent and shows a bcc structure. The critical diameter for transition from coherent rotation to curling mode is 35 nm for CoFe containing less than 40 at% Co while it is 30 nm for those with more than 40 at% Co. Optimizing the magnetic properties of CoFe with different Co content was seen to be dependent on the diameter of nanowires. For 25 nm diameter, the optimum was shown below 50 at% Co while it was seen above 50 at% for nanowires with 50 nm diameter. The angular dependence of the coercivity with nanowires diameter were also studied.     

Molecular Interactions in [Hmim][NO3] Ionic Liquid and 2-Alkanol Mixtures: Kirkwood–Buff Integrals and Structure Factor

Russian Journal of Physical Chemistry A - In this paper, the investigation on thermophysical properties, structure, and dominant interactions in the binary systems containing...     

Densities, viscosities, excess molar volumes, and refractive indices of acetonitrile and 2-alkanols binary mixtures at different temperatures: Experimental results and application of the Prigogine–Flory–Patterson theory

Densities, viscosities, and refractive indices of mixing of acetonitrile with 2-propanol, 2-butanol, 2-pentanol, 2-hexanol and 2-heptanol, have been measured as a function of composition at 293.15, 298.15, 303.15 and 308.15 K and ambient pressure. The excess molar volumes, viscosity and refractive index deviations calculated and fitted to Redlich–Kister polynomials. From the experimental data, partial molar volumes, and partial molar volumes at infinite dilution, were also calculated. The latter values are interesting from a theoretical point of view since at infinite dilution the only interactions present are solute solvent interactions. For mixtures of acetonitrile with used 2-alkanols, over the entire range of mole fractions, Δη is negative and both, and Δn_D are positive. The effect of temperature and chain-length of the 2-alkanols on the excess molar volumes, viscosity and refractive index deviations of its mixtures with acetonitrile are discussed in terms of molecular interaction between unlike molecules. The experimental results have been used to test the applicability of the Prigogine–Flory–Patterson (PFP) theory.     

Über heteroorganische Verbindungen, 38. Mitt.

Zusammenfassung S-Morpholino-dialkyl-dithiophosphate reagieren mit O,O-Dialkyl-dithiophosphorsäuren (mit denselben Alkylgruppen) zu den symmetrisch substituierten Bis-(dialkoxy-thiophosphoryl)-disulfiden1–5; mit O,O-Diphenyl-dithiophosphorsäure zu den entsprechenden unsymmetrisch substituierten Disulfiden6–7. Falls die Alkylgruppen der reagierenden Substanzen nicht identisch sind, wird ein Gemisch der zwei symmetrisch substituierten Disulfide erhalten. Ein Reaktionsmechanismus wird vermutet und experimentell gestützt.

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Heterocyclic compounds, XXXVIII.: New synthesis of bis-(dialkoxy-or-alkoxy-phenoxy-thiophosphoryl)disulfides

S-Morpholino-dialkyl-dithiophosphates react with O,O-dialkyl-dithiophosphoric acids containing the same alkyl-group to the symmetrically substituted bis-(dialkyl-dithiophosphoryl)-disulfides1–5; with O,O-diphenyl-dithiophosphoric acid to the corresponding unsymmetrically substituted disulfides6, 7. If the alkyl-groups of the two reagents are not identical, a mixture of the two symmetrically substituted disulfides is formed. A reaction mechanism is proposed and experimentally confirmed.

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37. Mitt.:L. Almasi undL. Paskucz, Chem. Ber., (im Druck).     

Synthesis and characterization of ultrafine γ-Al2O3:Cr nanoparticles and their performance in antibacterial activity

Journal of Sol-Gel Science and Technology - Preventing the growth of potentially deadly bacteria by newly synthesized nanoparticles (NPs) is of great importance in the development of future drugs....     

Pulse electrodeposition of Co1−xZnx nanowire arrays: Magnetic improvement through electrolyte concentration,off-time between pulses and annealing

Using different electrolyte compositions and varying the off-time between pulses, Co_1xZn_x nanowire arrays were fabricated by ac pulse electrodeposition. The effect of deposition parameters on alloy contents was investigated by studying the microstructures and magnetic properties of as-deposited and annealed Co_1xZn_x nanowires. It is shown that Zn content in CoZn nanowires exponentially increases by increasing the zinc ions in the electrolyte. The Zn content initially increases to a maximum by increase in off-time between pulses and then falls off. Adding a certain amount of Zn to Co led to form amorphous CoZn nanowires. A significant increase in magnetization, coercivity and squareness of CoZn nanowires was observed after annealing. The rate of increase in magnetization of annealed samples was seen to be inversely proportional to their initial magnetization. Improvement of magnetic properties of annealed samples may be caused by magnetic cluster formation and pinning effect.     

The influence of crystallinity enhancement on the magnetic properties of ac electrodeposited Fe nanowires

Fe nanowire arrays with different degrees of crystallinity were fabricated by ac electrodeposition into anodic aluminium oxide templates. A (110) preferential crystal orientation was observed for all the samples. An extensive investigation of X-ray patterns revealed that the variation of the magnetic properties is a direct consequence of the crystallinity degree of Fe nanowires. The results indicate that the degree of crystallinity varies with electrolyte acidity, waveform and frequency of the ac electrodeposition voltage. Regardless of the waveform and electrolyte acidity, higher deposition frequency induces higher coercivity. The effect of waveform and pH value on the magnetic properties is seen to be more pronounced in the low deposition frequency. Improving the ac electrodeposition conditions increased the coercivity and squareness from almost 1010 Oe and 0.49 to 1810 Oe and 0.99, respectively. It was seen that annealing improved the crystallinity, thereby increasing the coercivity and squareness.