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Legarra E.,Basque Center for Materials | Apinaniz E.,University of the Basque Country | Plazaola F.,University of the Basque Country
Intermetallics | Year: 2016

The influence of the different crystal structures and the variation of the lattice parameter on the evolution of the magnetism in the order-disorder transition produced by crushing and mechanical milling in the intermetallic Fe75Al25-xSix alloys (x = 7.5, 12.5, 17.5, 25) has been systematically studied by means of XRD measurements, Mössbauer spectroscopy and magnetic measurements. The results indicate that with the addition of Si to binary Fe75Al25 alloy the mechanical deformation needed to disorder the alloys increases. At the same time the variation of the lattice parameter due to the disorder is reduced as Si is added. The magnetic measurements indicate that there is a complex behaviour in ternary alloys with an opposite influence of Si and Al during the order-disorder transition. However, when the transition is fulfilled there is a linear relationship between structural and magnetic parameters. © 2015 Elsevier Ltd. Source

Trujillo S.,University of Glasgow | Lizundia E.,University of the Basque Country | Vilas J.L.,University of the Basque Country | Vilas J.L.,Basque Center for Materials | Salmeron-Sanchez M.,University of Glasgow
Colloids and Surfaces B: Biointerfaces | Year: 2016

This work investigates the effect of the sequential availability of ZnO nanoparticles, (nanorods of ~40 nm) loaded within a degradable poly(lactic acid) (PLLA) matrix, in cell differentiation. The system constitutes a dynamic surface, in which nanoparticles are exposed as the polymer matrix degrades. ZnO nanoparticles were loaded into PLLA and the system was measured at different time points to characterise the time evolution of the physicochemical properties, including wettability and thermal properties. The micro and nanostructure were also investigated using AFM, SEM and TEM images. Cellular experiments with C2C12 myoblasts show that cell differentiation was significantly enhanced on ZnO nanoparticles-loaded PLLA, as the polymer degrades and the availability of nanoparticles become more apparent, whereas the release of zinc within the culture medium was negligible. Our results suggest PLLA/ZnO nanocomposites can be used as a dynamic system where nanoparticles are exposed during degradation, activating the material surface and driving cell differentiation. © 2016 Elsevier B.V. Source

Legarra E.,Basque Center for Materials | Apinaniz E.,University of the Basque Country | Plazaola F.,University of the Basque Country
Journal of Alloys and Compounds | Year: 2016

The aim of this work is to study the influence of the coexistence of different ordered structures on the evolution of the magnetism in the order-disorder transition produced by crushing and mechanical milling in the intermetallic Fe70Al30-xSix alloys. First, XRD measurements show that the three ordered samples have both D03 and B2 structures simultaneously and that the disordering process takes place in two stages. In the first one the D03 structure starts to disorder and in the second one, once the D03 structure has almost disappeared, the B2 starts to disorder. Second, Mössbauer spectroscopy and magnetic measurements show that there is an enhancement of the magnetic properties related to the structure change and to the increase of the lattice parameter in the order-disorder transition. The change of the magnetic behaviour is linked to the disordering of B2 structure in these alloys. © 2016 Elsevier B.V. Source

Maceiras A.,University of the Basque Country | Martins P.,University of Minho | Martins P.,International Iberian Nanotechnology Laboratory | Gonc alves R.,University of Minho | And 9 more authors.
European Polymer Journal | Year: 2015

The use of polymer based magnetoelectric materials for sensing and actuation applications has been the subject of increasing scientific and technological interest. One of the drawbacks to be overcome in this field is to increase the temperature range of application above 100°C. In this way, a nanocomposite material composed by a mixture of two aromatic diamines, 1,3-bis-2-cyano-3-(3 aminophenoxy)phenoxybenzene (diamine 2CN) and 1,3-bis(3-aminophenoxy)benzene (diamine 0CN) and CoFe2O4 (CFO) nanoparticles was designed, fabricated and successfully tested for high temperature magnetoelectric applications. Results revealed that CFO nanoparticles are well distributed within the 0CN2CN polymer matrix and that the addition of CFO nanoparticles does not significantly alter the polyimides structure. The magnetization response of the composite is determined by the CFO nanoparticle content. The piezoelectric response of the 0CN2CN polymer matrix (≈11 pC N-1) and the maximum α33 value (0.8 mV cm-1 Oe-1) are stable over time and decrease only when the composite is subjected to temperatures above 130°C. Strategies to further improve the ME response are also discussed. © 2015 Elsevier Ltd. All rights reserved. Source

Goncalves R.,University of Minho | Martins P.,University of Minho | Correia D.M.,University of Minho | Sencadas V.,University of Minho | And 5 more authors.
RSC Advances | Year: 2015

Magnetoelectric microspheres based on piezoelectric poly(vinylidene fluoride) (PVDF) and magnetostrictive CoFe2O4 (CFO), a novel morphology for polymer-based ME materials, have been developed by an electrospray process. The CFO nanoparticle content in the (3-7 μm diameter) microspheres reaches values up to 27 wt%, despite their concentration in the starting solution reaching values up to 70 wt%. Additionally, the inclusion of magnetostrictive nanoparticles into the polymer spheres has no relevant effect on the piezoelectric β-phase content (≈60%), crystallinity (40%) and the onset degradation temperature (460-465°C) of the polymer matrix. The multiferroic microspheres show a maximum piezoelectric response d33 ≈ 30 pC N-1, leading to a magnetoelectric response of Δd33 ≈ 5 pC N-1 obtained when a 220 mT DC magnetic field was applied. It is also shown that the interface between CFO nanoparticles and PVDF (from 0 to 55%) has a strong influence on the ME response of the microspheres. The simplicity and the scalability of the processing method suggest a large application potential of this novel magnetoelectric geometry in areas such as tissue engineering, sensors and actuators. © The Royal Society of Chemistry 2015. Source

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