Browsing by Author "Murillo, N."
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Item Magnetic and magnetostrictive behavior of amorphous and nanocrystalline (by current annealing) Fe86Zr7B6Cu1 alloy(1997-09) Zuberek, R.; Murillo, N.; González, J.; Blanco, J. M.; García-Tello, P.; Tecnalia Research & InnovationA reinforcement of the ferromagnetic character with applied tensile stress has been found in Fe86Zr7B6Cu1 amorphous alloy with a linear relationship between the change of the magnetization per unit stress. By annealing with electric current, an improvement of the magnetic softness of the alloy can be achieved in the range of current density of 50 to 75 Axmm-2. Such an effect is connected to the presence of ultrafine grains of dimensions typically of nanometers. Results of the magnetostriction constant are also report edfor the as-quenched and nanocrystalline alloy which are interpreted in terms of surface and bulk contributions from α-Fe grains.Item Optical sensors based on polymeric nanofibers layers created by electrospinning(2018) Ponce-Alcántara, S.; Martín-Sánchez, D.; Pérez-Márquez, A.; Maudes, J.; Murillo, N.; García-Rupérez, J.; PRINTEX; Tecnalia Research & InnovationPorous materials have become ideal candidates for the creation of optical sensors that are able to reach extremely high sensitivities, due to both the possibility to infiltrate the target substances on them and to their large surface-to-volume ratio. In this work, we present a new alternative for the creation of porous optical sensors based on the use of polymeric nanofibers (NFs) layers fabricated by electrospinning. Polyamide 6 (PA6) NFs layers with average diameters lower than 30 nm and high porosities have been used for the creation of Fabry-Pérot optical sensing structures, which have shown an experimental sensitivity up to 1060 nm/RIU (refractive index unit). This high sensitivity, together with the low production cost and the possibility to be manufactured over large areas, make NFs-based structures a very promising candidate for the development of low-cost and high performance optical sensors.Item Structural and magnetic properties of sintered Sr-ferrites fabricated by powder injection molding(1999-08) Murillo, N.; González, J.; Guraya, C.; Gutiérrez, M.; Seco, F. J.; EXTREMAT; Tecnalia Research & InnovationStudies of micro structure (SEM and metalographic micrographs) and magnetic properties (remanent magnetisation and coercive field) have been performed on bipolar sintered Sr-ferrite permanent magnets obtained by powder injection molding (PIM) method under applied magnetic field in order to align the magnetic particles during the PIM process. Magnetic measurements on the samples were made in the parallel and perpendicular direction of the aligning magnetic field. The remanence in the direction of alignment increased sharply with the alignment field to a maximum value of 3840 Gs while the coercivity decreases to a minimum value of 3220 Oe.