Influence of TiO2-Coating Layer on Nanoporous Alumina Membranes by ALD Technique

Geometrical, chemical, optical and ionic transport changes associated with ALD of TiO2-coating on the porous structure of two nanoporous alumina membranes (NPAMs), which were obtained by the two-step aluminum anodization method but with different pore size and porosity, are presented. Chemical and morphological changes were determined by analyzing XPS spectra and SEM images, showing practically total coverage of the NPAMs surface and leading to a reduction in the geometrical parameters of both samples, while SAED and high resolution TEM measurements allowed us to determine the crystalline structure and thickness of the TiO2-coating, with the latter confirmed by depth-profile XPS analysis. Spectroscopic ellipsometry measurements were also carried out in order to detect changes in characteristic optical parameters (refractive index, n, and extinction coefficient, k), due to the TiO2-coating of NPAMs. Considering the common application of NPAMs in solute/ion diffusion processes, the effect of the TiO2-coverage on electrochemical parameters was analyzed by measuring the concentration potential with a typical model electrolyte (KCl solutions), leading to an increase of the electropositive character for both kinds of samples

Magnetic properties and giant magnetoimpedance in amorphous and nanocrystalline microwires

We studied magnetic properties and GMI effect of Finemet-type FeCuNbSiB microwires. We observed that GMI effect and magnetic softness of microwires produced by the Taylor-Ulitovski technique, can be tailored by either controlling magnetoelastic anisotropy of as-prepared FeCuNbSiB microwires or controlling their structure by heat treatment or changing the fabrication conditions. GMI effect has been observed in as-prepared Fe-rich microwires with nanocrystalline structure.This work was supported by EU ERA-NET programme under project "SoMaMicSens" (MANUNET-2010-Basque-3), by Spanish MICINN under project MAT2010-18914, by the Basque Government under Saiotek-12 MEMFOMAG project (S-PE12UN139) and by federal target program "Scientific and scientific-pedagogical personnel of innovative Russia", state contract no 14.R18.21.0762. A. Zh. and V.Zh. wish to acknowledge support of the Basque Government under the Mobility Program (grants MV-2013-2-22 and MV-2013-2-23). Technical and human support provided by SGIker (UPV/EHU, MICINN, GV/EJ, ERDF and ESF) is gratefully acknowledged

Giant magnetoimpedance effect in nanocrystalline microwires

We studied GMI effect and magnetic properties of Finemet-type FeCuNbSiB microwires. We observed that GMI magnetic field and frequency dependences and magnetic softness of composite microwires produced by the Taylor-Ulitovski technique can be tailored either controlling magnetoelastic anisotropy of as-prepared FeCuNbSiB microwires or controlling their structure by heat treatment or changing the fabrication conditions. GMI effect has been observed in as-prepared Fe-rich microwires with nanocrystalline structure.This work was supported by EU ERA-NET programme under project "SoMaMicSens" (MANUN ET-2010-Basque-3), by EU under FP7 "EM-safety" project, by Spanish Ministry of Science and Innovation, MICINN under Project MAT2010-18914, by the Basque Government under Saiotek 11 MICMAGN project (S-PE11UN087) and by federal target program "Scientific and scientific-pedagogical personnel of innovative Russia", state contract No. 14.18.21.0783

Tailoring of magnetocaloric effect in Ni45.5Mn43.0In11.5 metamagnetic shape memory alloy

We investigate the direct and inverse magnetocaloric effect in Ni45.5Mn43.0In11.5 Heusler alloy ribbons comparing the results obtained for the as-quenched sample with the ones after different annealing procedures. An enhancement and shift of the entropy maximum to near room temperature is observed in all annealed samples. A remarkable magnetocaloric effect is observed in samples with short-time treatment (10 minutes) and at the lowest annealing temperature. We show that the suppressing of uncompensated martensitic transition and thermal hysteresis are both influenced by the heat treatment. Also, an improvement on Curie’s temperature is observed and, at low magnetic field, it has been risen up to 310 K. Our results demonstrate that the martensitic transformation is highly sensitive to the applied magnetic field and also to the annealing treatment, which means that the magnetocaloric effect can be tuned showing different behaviors for each sample.Authors are thankful to Spanish MICINN for financial support: MAT2009-13108-C02-01-02 and MAT2010-20798-C05-04. L. Gonzalez also thanks MICINN for a FPI Grant and J. García FICYT for a “Severo Ochoa” Grant

The study of magnetization process in amorphous FeNiSiB microwires

Czech and Slovak Conference on Magnetism (14. Košice, Slovakia. 2010