Search

En el presente trabajo, se lleva a cabo un estudio sobre las propiedades mecánicas de chapa de dos aceros avanzado de alta resistencia. La búsqueda de un modelo teórico que defina su comportamiento en régimen plástico, así como la comparativa de sus resultados con el fin de predecir su comportamiento en etapas de conformado, y ayudar a optimizar los resultados en simulación mediante elementos finitos. También se añade un ejemplo de simulación para ver la importancia de la precisión del cálculo de las propiedades mecánicas en este campo. En el present projecte es du a terme un estudi sobre les propietats mecàniques de dues xapes d'acers avançats d'alta resistència. També es busca un model teòric per definir el comportament del material a règim plàstic, així com la comparativa d'ambdues xapes amb la finalitat de preveure el seu comportament en etapes de conformat i ajudar a optimitzar els resultats en simulació mitjançant elements finits. També s'afegeix un exemple de simulació per veure la importància de les propietats mecàniques en aquest camp.

Las cerámicas técnicas se han identificado como uno de los primeros campos donde las mayores mejoras en el procesado y la obtención de productos más avanzados se podrán alcanzar. Avances en la tecnología del procesado cerámico se requerirán para la comercialización de nuevos productos y para el mantenimiento de la competitividad en los productos ya consolidados. El molino de atrición es capaz de suministrar alta energía en el proceso de molienda consiguiendo mayores reducciones de tamaño de partícula. El procesado con el molino de atrición permite conseguir partículas submicrónicas que facilitan las etapas de conformado posterior y mejoran las propiedades del producto final. Esta alta eficiencia del molino de atrición hace que se puedan conseguir partículas en el rango incluso manométrico lo que tiene interesantes implicaciones tecnológicas. El objetivo principal de este trabajo es el estudio de los parámetros que afectan a la desaglomeración y molturación del material de partida, más una caracterización de la microestructura y de las propiedades mecánicas que genera en el material desarrollado.

La finalitat d'aquest projecte és l'adquisició d'un nou coneixement científic i tecnològic que permeti desenvolupar nous materials a partir de la producció de nanofibres de carboni, que responguin a necessitats de diferents sectors tecnològics i millorin les propietats mecàniques, elèctriques i tèrmiques dels materials existents. En tant això, l'objectiu d'aquest projecte és obtenir una sèrie de mostres de diferents nanofibres de carboni amb propietats controlades. Aquestes estaran generades a partir de diferents paràmetres, com són la temperatura, el temps, el tipus de catalitzador, el tipus de preparació d'aquest i l'aplicació d'un camp magnètic. Un altre dels objectius és realitzar una purificació de les mostres obtingudes. Com també crear diferents compòsits a partir d'una matriu polimèrica termoplàstica d'acrilonitril butadiè estirè (ABS) i nanofibres de carboni, tant purificades com sense purificar, per finalment estudiar les conductivitats elèctriques i tèrmiques dels compòsits elaborats. En aquest estudi s'han emprat materials accessibles comercialment, amb la finalitat d'agilitzar la fase experimental i aconseguir sistemes més fàcilment reproduïbles.

En aquest treball es pretén obtenir material porós de PDLLA, amb ús potencial com a bastida en enginyeria tissular, mitjançant l'ús de freó R-134a com a fluid escumant. Per aquest motiu, s'ha realitzat un estudi on es valoren diferents variables com la temperatura de procés, la pressió de treball i l'ús de N2 en la despressurització que poden modificar la microestructura final de la bastida. The aim of this project is to obtain PDLLA porous material. To use it as a scaffold in tissular engineering, through R-134a Freon as foaming gas. For this reason, many operational parameters like process temperature, working pressure and the use of N2 in depressurization have been studied to evaluate the influence of each one in the final microstructure of scaffolds.

Nota: Aquest document conté originàriament altre material i/o programari només consultable a la Biblioteca de Ciència i Tecnologia.

A study of the main types of coatings and its processes that modern industry commonly apply to prevent to the corrosion due to the environmental effects to energetic market pipelines have been done. Extracting main time and temperature range values, coating heat treatment recreation have been applied to x65 pipelines steel grade samples obtained from a pipe which was formed using UOE forming process. Experimental tensile tests and Charpy V-Notch Impact test have been carried out for a deeply knowledge of the influence on the steel once this recreations are applied. The Yield Strength and toughness have been improved despite lower values in rupture strain and ductile-brittle temperature transition have been obtained. Finite Element Method have been applied to simulate the entirely pipe cold bending process to predict the mechanical properties and behaviour of the pipe made from x65 steel grade under different conditions. L'estudi dels tipus de recobriments i processos principals que la indústria moderna actual aplica per tal de prevenir la corrosió degut als efectes mediambientals sobre les canonades usades en el sector energètic ha sigut realitzat. Extraient els principals rangs de valors de temps i temperatura, la recreació dels tractaments tèrmics dels processos de recobriment han sigut aplicats sobre acer de tuberies x65 obtingut d'una canonada fabricada utilitzant el procés UOE de fabricació. Tests experimentals de tracció i d'impacte Charpy amb entalla en V han sigut realitzats per tal d'obtenir un profund coneixement de la seva influència en l'acer un cop aplicats aquests tractaments tèrmics. El límit elàstic i la tenacitat han sigut millorades malgrat valors més baixos de deformació última i de temperatura de transició fragil-dúctil han sigut obtinguts. Mètodes d'elements Finits han sigut aplicats per tal de simular el procés complet de flexió en fred de canonades per tal de predir les propietats mecàniques finals així com el comportament de la canonada feta d'acer x65 sota diferents condicions. Nota: Aquest document conté originàriament altre material i/o programari només consultable a la Biblioteca de Ciència i Tecnologia.

L'objectiu d'aquest projecte és sintetitzar i caracteritzar nanopartícules d'òxid de cobalt. Ens interessa estudiar diferents isomorfes de monòxid de cobalt (CoO) ja que són materials nous i se'n desconeixen les propietats; en algunes investigacions s'intueix un comportament antiferromagnètic la qual cosa les fa especialment interessants per aplicacions magnètiques.

The study was performed at OCAS, the Steel Research Centre of ArcelorMittal for the Industry market. The major aim of this research was to obtain an optimized tensile testing methodology with in-situ H-charging to reveal the hydrogen embrittlement in various high strength steels. The second aim of this study has been the mechanical characterization of the hydrogen effect on hight strength carbon steels with varying microstructure, i.e. ferrite-martensite and ferrite-bainite grades. The optimal parameters for H-charging - which influence the tensile test results (sample geometry type of electrolyte, charging methods effect of steel type, etc.) - were defined and applied to Slow Strain Rate testing, Incremental Step Loading and Constant Load Testing. To better understand the initiation and propagation of cracks during tensile testing with in-situ H-charging, and to make the correlation with crystallographic orientation, some materials have been analyzed in the SEM in combination with the EBSD technique. The introduction of a notch on the tensile samples permits to reach a significantly improved reproducibility of the results. Comparing the various steel grades reveals that Dual Phase (ferrite-martensite) steels are more sensitive to hydrogen induced cracking than the FB (ferritic-bainitic) ones. This higher sensitivity to hydrogen was found back in the reduced failure times, increased creep rates and enhanced crack initiation (SEM) for the Dual Phase steels in comparison with the FB steels.

4 páginas, 3 figuras.-- et al., A correlation between the grain orientation and the out-of-plane magnetic properties of nitrogen-enriched polycrystalline austenitic stainless steel surface is performed. Due to the competition between the magnetocrystalline anisotropy, the exchange and dipolar interactions, and the residual stresses induced by nitriding, the resulting effective magnetic easy-axis can lay along unusual directions. It is also demonstrated that, by choosing an appropriate stainless steel texturing, arrays of ferromagnetic structures with out-of-plane magnetization, embedded in a paramagnetic matrix, can be produced by local plasma nitriding through shadow masks., This work has been partially financed by the Catalan DGR and the Spanish MICINN (Grant Nos. 2009-SGR- 1292, MAT2007-66309-C02, and MAT2007-61629). E.M. thanks the Fund for Scientific Research—Flanders FWO for financial support. M.D.B. was partially supported by an ICREA ACADEMIA award.

The influence of chemistry and soaking temperature (maximal temperature of the continuous annealing) on the final properties of non-oriented electrical steels has been studied. With this objective two different studies have been performed. First the Mn, Ni and Cr content of a low loss electrical steel composition has been modified. An intermediate content and a high content of each element has been added in order to study the influence of this components on the magnetic looses, grain size and texture. Secondly the influence of the soaking temperature on magnetic properties, grain size and oxidation in four grades of non-oriented electrical steels (Steel A, B, C and D) was studied.

Premi a l'excel·lència investigadora. Àmbit de les Ciències Tecnològiques. 2008 The effect of imprinting symmetric and displaced vortex structures into an antiferromagnetic material is investigated in micron-sized disks consisting of exchange coupled ferromagnetic-antiferromagnetic bilayers. The imprint of displaced vortices manifests itself by the occurrence of a new type of asymmetric hysteresis loops characterized by curved, reversible, central sections with nonzero remanent magnetization. Such an imprint is achieved by cooling the disks through the blocking temperature of the system in small fields. Micromagnetic simulations reveal that asymmetric vortexlike loops naturally result from the competition between the different energies involved in the system.

Mesoporous Fe-Pt thin films are obtained by micelle-assisted electrodeposition onto metallic substrates with dissimilar activity (namely, gold, copper, and aluminum seed layers evaporated on Si/Ti) under constant applied potential (E=-1.1 V vs. Ag/AgCl) and deposition time (600 s). The amphiphilic triblock copolymer Pluronic P-123 is used as a soft template to guide the formation of mesopores. The occurrence of pores (ca. 7 nm in diameter) with narrow size distribution, distributed evenly over the surface, is observed in all cases. Despite the applied conditions being the same, the roughness and the amount of Fe incorporated in the films are influenced by the nature of the substrate. In particular, ultra-smooth films containing a larger amount of Fe (21 wt %) are obtained when deposition takes place on the Au surface. X-ray diffraction analyses reveal that Pt and Fe are alloyed to a certain extent, although some iron oxides/hydroxides also unavoidably form. The resulting films have been tested as electrocatalysts in the hydrogen evolution reaction (HER) in alkaline media. The mesoporous Fe-rich Fe-Pt films on Au show excellent HER activity and cyclability.

Mesoporous Ni-doped SnO₂ thin films synthesized from variable [Ni(II)/Sn(IV)] molar ratios (0 : 100, 5 : 95, 10 : 90, 15 : 85 and 20 : 80), thicknesses in the range of 100-150 nm, and average pore sizes lower than 10 nm were obtained through a sol-gel based self-assembly process using Pluronic P-123 as a structure-directing agent. Grazing incidence X-ray diffraction experiments indicate that the films mostly possess a tetragonal SnO₂ structure with Ni²+ in substitutional positions, although energy-dispersive X-ray analyses also reveal the occurrence of small NiO clusters in the films produced from high [Ni(II)/Sn(IV)] molar ratios (corresponding to a Ni amount of 8.6 at%). X-ray photoelectron spectroscopy experiments indicate the lack of metallic Ni and the occurrence of oxygen vacancies in the mesoporous films. Interestingly, the magnetic properties of these mesoporous films significantly vary as a function of the doping percentage. The undoped SnO₂ films exhibit a diamagnetic behavior, whereas a clear paramagnetic signal dominates the magnetic response of the Ni-doped mesoporous films, probably due to the presence of NiO as a secondary phase. A small ferromagnetic-like contribution superimposed to the paramagnetic background is observed for samples with high Ni contents, possibly stemming from the combined effect from Ni incorporation and the occurrence of oxygen vacancies.

Gnm3 Altres ajuts: Basque Government ELKARTEK, FN KK-2015/0010 ZrO₂-decorated ZnO (ZrO₂/ZnO) nanoparticles (NPs) have been synthesized by a facile co-precipitation method in the presence of cetyltrimethylammonium bromide (CTAB) surfactant. The ZrO₂ amount in the NPs has been varied from 1.0, 2.0, 4.9, to 9.3% by weight. The resulting NPs are heterostructured and consist of a crystalline ZnO core (wurtzite phase) surrounded by an amorphous ZrO₂ layer. X-ray diffraction analyses support this observation. The NPs show a narrow size distribution and are slightly elongated. Compared to pure ZnO NPs, the hybrid ZrO₂/ZnO ones show enhanced photocatalytic activity toward the degradation of Rhodamine B under UV-Vis light. Such enhancement has been partly attributed to the increased amount of oxygen vacancies when ZrO₂ is incorporated into the NPs, as shown by X-ray photoelectron spectroscopy analyses.

Two new Fe-based alloys, Fe-10Mn6Si1Pd and Fe-30Mn6Si1Pd, have been fabricated by arc-melting followed by copper mold suction casting. The Fe-30Mn6Si1Pd alloy mainly consists of ε-martensite and γ-austenite Fe-rich phases whereas the Fe-10Mn6Si1Pd alloy primarily contains α-Fe(Mn)-ferrite phase. Additionally, Pd-rich precipitates were detected in both alloys. Good mechanical response was observed by nanoindentation: hardness values around 5.6 GPa and 4.2 GPa and reduced Young's modulus values of 125 GPa and 93 GPa were measured for the as-prepared Fe-10Mn6Si1Pd and Fe-30Mn6Si1Pd alloys, respectively. Both alloys are thus harder and exhibit lower Young's modulus than 316L stainless steel, which is one of the most common Fe-based reference materials for biomedical applications. Compared with the ferromagnetic Fe-10Mn6Si1Pd alloy, the paramagnetic Fe-30Mn6Si1Pd alloy is more appropriate to be used as an implant since it would be compatible with nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) analyses. Concerning biocompatibitliy, the more hydrophilic Fe-10Mn6Si1Pd shows improved cell adhesion but its pronounced ion leaching has a negative effect on the proliferation of cells. The influence of immersion in simulated body fluid on composition, microstructure, mechanical and magnetic properties of both alloys is assessed, and the correlation between microstructure evolution and physical properties is discussed.

Ni (1 wt%)-, Pt (1 wt%)- and [Ni (0.5 wt%)/Pt (0.5 wt%)]-doped TiO₂ nanoporous catalysts have been successfully obtained through a facile two-step hydrothermal route. TiO₂ crystallizes mostly in the anatase phase and acts as a mesoporous matrix. Meanwhile, Ni, Pt and Ni/Pt dopants form small nanoparticles (NPs) (3-95 nm in diameter) which are hosted by the TiO₂ framework. The resulting composites exhibit a rather large surface area, in the range of 186-200 m2/g. The band gap energy reduces from 3.03 eV for the undoped TiO₂ to 2.15 eV for the Pt-loaded TiO₂. As a consequence, absorption expands toward the visible light range. The photodegradation of Rhodamine B dye in aqueous medium has been investigated under UV-vis light irradiation. The presence of Ni, Pt and Ni/Pt NPs significantly enhances the photocatalytic activity of the material. Furthermore, the Ni-doped TiO₂ shows ferromagnetic behavior at room temperature, which makes its recovery and subsequent fast reutilization possible. Interestingly, this sample also exhibits the best stability upon recycling. Considering all the current challenges in sustainable water remediation, these new photocatalysts could find applications in real environmental contexts in the near future.

Glass-forming Ti-based alloys are considered as potential new materials for implant applications. Ti75-xZr10NbxSi15 alloys (free cytotoxic elements) can be produced as melt-spun ribbons with glassy matrix and embedded single β-type macrocrystals. The corrosion and passivation behavior of these alloys in their homogenized melt-spun states have been investigated in Ringer solution at 37º C in comparison to their cast multiphase crystalline counterparts and to cp-Ti and β-type Ti-40Nb. All tested materials showed very low corrosion rates as expressed in corrosion current densities i corr

Altres ajuts: China Scholarship Council (CSC)/201406220145 i China Scholarship Council (CSC)/201306250050 Undoped and Ni-doped ordered mesoporous SnO₂ powders ([Ni(II)]/[Sn(II)] = 0 : 100, 5 : 95, 15 : 85, 20 : 80) were synthesized by nanocasting from mesoporous KIT-6 silica. The resulting Ni content in the Ni-loaded powders ranged between 1 at% and 9 at%. Successful replication of the silica template was verified by scanning electron microscopies for all samples. Residual silicon content did not surpass 4 at%. X-ray diffraction analyses showed that the powders were nanocrystalline, being the rutile-like phase of SnO₂ the dominant structure. Changes in the lattice constants depending on the Ni content were observed, suggesting that Ni enters the rutile structure of SnO₂ to some extent. No extra phases attributed to Ni were detected in the powders except for the sample synthesized from 20 : 80 [Ni(II)]/[Sn(II)], for which NiO as secondary phase was observed. The oxidation state and spatial distribution of Ni in the powders was investigated by X-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS) measurements, respectively. For 6 at% and 9 at% Ni content, the presence of Ni2+ was established. The corresponding EELS mapping showed that a fraction of Ni (the one not forming part of the rutile phase) tended to accumulate at the pore edges, forming a nanometer-thick NiO layer. Compared to undoped SnO₂, Ni-containing powders exhibit a ferromagnetic response at low and room temperatures. Uncompensated spins at the surface of NiO are likely to contribute, in part, to the observed ferromagnetic properties.

Here it is demonstrated that multiple-energy, anomalous small-angle X-ray scattering (ASAXS) provides significant enhancement in sensitivity to internal material boundaries of layered nanoparticles compared with the traditional modeling of a single scattering energy, even for cases in which high scattering contrast naturally exists. Specifically, the material-specific structure of monodispersed Fe₃O₄|γ-Mn₂O₃ core|shell nanoparticles is determined, and the contribution of each component to the total scattering profile is identified with unprecedented clarity. We show that Fe₃O₄|γ-Mn₂O₃ core|shell nanoparticles with a diameter of 8.2 ± 0.2 nm consist of a core with a composition near Fe₃O₄ surrounded by a (Mn(x)Fe(1-x))₃O₄ shell with a graded composition, ranging from x ≈ 0.40 at the inner shell toward x ≈ 0.46 at the surface. Evaluation of the scattering contribution arising from the interference between material-specific layers additionally reveals the presence of Fe₃O₄ cores without a coating shell. Finally, it is found that the material-specific scattering profile shapes and chemical compositions extracted by this method are independent of the original input chemical compositions used in the analysis, revealing multiple-energy ASAXS as a powerful tool for determining internal nanostructured morphology even if the exact composition of the individual layers is not known a priori.

Aquest projecte s'ha realitzat al Servei de Microscòpia de la Universitat Autònoma de Barcelona, i ha tingut una durada de dos anys (2007-2009). Els objectius concrets d'aquest projecte assolits per a les diferents assignatures ha estat l'anàlisi de característiques citològiques, característiques morfològiques i anatòmiques de les estructures vegetatives dels diferents nivells d’organització, característiques morfològiques i anatòmiques de les estructures reproductores. El material docent obtingut en aquest projecte està sent utilitzat en les assignatures següents: Botànica Farmacèutica, Biodiversitat vegetal marina, Recursos vegetals aquàtics: les algues, Plantes d'ús alimentari, Conserv. i gestió de poblacions i comunitats marines, Usos i cultius de recursos algals marins, B. i diversitat de criptògames, Biologia II, Tècniques Exp. de biologia II, Botànica, Biologia animal i vegetal. Per a la realització de l’estudi, s'ha obtingut una col·lecció d’imatges al MLC, MER i MET per aclarir els criteris sistemàtics. Durant el primer any s’han adquirit totes les imatges necessàries, per tal de poder elaborar el material didàctic en suport digital. Durant el segon any s’ha implementat aquest material a les respectives classes pràctiques i s’ha avaluat la seva importància en la millora de la formació dels alumnes i del suport al professor. L’aplicació del material elaborat a la docència pràctica durant el tot segon any ha permès fer un primer estudi per valorar la seva eficàcia i fer-hi les correccions oportunes. Durant tot el projecte, el treball conjunt de professors i tècnics ha estat bàsic per a l’obtenció de material didàctic adequat a la realitat dels estudis actuals i a la docència pràctica. This project has been carried out at the Servei de Microscopia of the Universitat Autonoma de Barcelona, and lasted two years (2007-2009). The specific objectives of this project for the different subjects have been the analysis of cytological characteristics, anatomical and morphological characteristics of vegetative structures at different levels of organization, and morphological and anatomical structures breeder. The teaching material obtained in this project is being used in the following subjects: Pharmaceutical Botany, Plant Biodiversity, Marine Resources aquatic plants: algae, plants use food preserves. and management of marine populations and communities, customs and cultures of marine algal resources, B. Biology II, Techniques Exp. Biology II, Botany, Animal and Plant Biology. For the realization of the study, a collection of images have been obtained by using MLC, MER MET to clarify the criteria and systematic. During the first year, all necessary images have been acquired, in order to produce the material in digital form. During the second year, this material has been implemented in the respective practical classes and its importance in improving both the training of students as well as teacher support has been evaluated. The application of the material prepared for teaching practice during the entire second year has allowed the first study to evaluate its effectiveness and make necessary corrections. Throughout the project, the collaborative work between teachers and technicians has been a key factor to obtain a material suitable to the reality of current studies and teaching practices.

Aquest projecte s'ha realitzat al Servei de Microscòpia de la Universitat Autònoma de Barcelona, i ha tingut una durada de dos anys (2006-2008). La finalitat d’aquest projecte ha estat l’elaboració de material didàctic basat en la captació d’imatges i l’edició de recursos pedagògics de suport digital aplicats a la ciència de materials. Es pretén millorar així la qualitat docent de les pràctiques de diverses assignatures dels ensenyaments de Física i d’Enginyeria de Materials utilitzant tècniques d’anàlisi actuals com són la Microscòpia Electrònica de Rastreig (MER) i la Microscòpia Optica (MO). Amb aquest projecte es vol fomentar també el treball interdisciplinari en equip entre professionals (docents i tècnics superiors de recerca) i acostar la teoria de les assignatures a la realització pràctica, facilitant el suport digital necessari per aconseguir un màxim aprofitament a les aules. Les imatges de MER i MO ajudaran als alumnes a familiaritzar-se amb el món de la recerca i la indústria. This project has been carried out at the Microscopy Service of the Universitat Autònoma de Barcelona, and has had a duration of two years (2006-2008). The purpose of this project has been the elaboration of didactic material based on the recording of images and the edition of pedagogic resources of digital support applied to the science of materials. It is intended to improve like this the educational quality of the practices of several subjects of the education of both Physics and Engineering of Materials using current techniques of analysis such us the Scanning Electron Microscopy (SEM) and the Optical Microscopy (OM). With this project it is wanted to foment also the interdisciplinary work among professionals (teachers and superior research technicians) and to bring over the theory of the subjects in the practical realization, facilitating the necessary digital support to achieve a maximum exploitation to the classrooms. The images of SEM and OM will help to the students to familiarize oneself with the world of the research and the industry.

Acesso restrito: Texto completo. p. 2651-2657. Submitted by JURANDI DE SOUZA SILVA (jssufba@hotmail.com) on 2012-04-12T18:27:41Z No. of bitstreams: 1 __ac.els-cdn.com_S002230...a0d551c3e334826f0421566aa4f12.pdf: 511365 bytes, checksum: a8e44dd00c5d8c06e2f394fce568a529 (MD5) Made available in DSpace on 2012-04-12T18:27:41Z (GMT). No. of bitstreams: 1 __ac.els-cdn.com_S002230...a0d551c3e334826f0421566aa4f12.pdf: 511365 bytes, checksum: a8e44dd00c5d8c06e2f394fce568a529 (MD5) Previous issue date: 2010-10 The present paper evaluates the corrosion resistance of four new amorphous Fe-Cr-based alloys containing Mo or Nb, as well as their thermal stability and the effect of their partial crystallization. Ribbons of Fe68B20Cr12, Fe67.7B20Cr12Mo0,3, Fe67.7B20Cr12Nb0,3 and Fe67.7B20Cr12Nb0,15Mo0,15 alloys were processed by the melt-spinning technique. The crystallization process of the four compositions occurs in a single-stage step with the simultaneous precipitation of fcc-Fe and Fe3.5B phases. The addition of Nb and/or Mo leads to an increase in the crystallization temperature, indicating that these elements stabilize the amorphous phase. The results also indicate that the alloy containing both Nb and Mo presented greater uniform corrosion resistance than the alloy containing either one or the other of these elements in NaCl and H2SO4 solution.

L'Escola d'Estiu del projecte Women-in-Nano va tenir lloc a Coma-ruga del 2 al 6 del passat mes de juny amb el títol "Desenvolupament de la carrera i tendències en la recerca". Aquesta activitat va ser organitzada per la Professora Maria Dolors Baró, catedràtica del Departament de Física de la UAB, dins del projecte "Enfortint el paper de les dones científiques a la nanociència", una iniciativa de la Comissió Europea enquadrada en el 6è Programa Marc en Recerca, Desenvolupament Tecnològic i Demostració. La Escuela de Verano del proyecto Women-in-Nano tuvo lugar en Coma-ruga del 2 al 6 del pasado mes de junio bajo el título "Desarrollo de la carrera y tendencias en la investigación". Esta actividad fue organizada por la Profesora Maria Dolors Baró, catedrática del Departamento de Física de la UAB, dentro del proyecto "Fortaleciendo el papel de las mujeres científicas en la nanociencia", una iniciativa de la Comisión Europea encuadrada en el 6o Programa Marco en Investigación, Desarrollo Tecnológico y Demostración.

This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The magnetization reversal in Permalloy (Py) and Py-IrMn disks (1μm diameter) is investigated. The Py disks reverse their magnetization via vortex state formation. Conversely, if the Py-IrMn disks are field cooled from above the blocking temperatureTB, a critical angle with respect to the cooling direction is set, beyond which the vortex no longer nucleates. This angle can be experimentally tuned by varying the magnitude of the exchange bias field. Furthermore, the coupling with IrMn can also induce an enhancement of the vortex stability when the disks are zero-field cooled from above TB.