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Laser-induced periodic surface structures (LIPSS) represent a unique route for functionalizing materials through the fabrication of surface nanostructures. Commercial AISI 316L stainless steel (SS316L) surfaces are laser treated by ultraviolet 300 ps laser pulses in a laser line scanning (LLS) approach. Processing parameters are optimized (pulse energy of 2.08 µJ, pulse repetition frequency of 300 kHz, and suitable laser scan and sample displacement rates) for the generation of low spatial frequency LIPSS over a large 25 × 25 mm2 area. Different angles of incidence of the laser radiation (0°, 30°, and 45°) and different linear laser beam polarizations (s and p) produce a plethora of rippled surface morphologies at distinct grains. Scanning electron microscopy and 2D Fourier transforms, together with calculations of the optical energy deposited at the treated surfaces using Sipe's first-principles electromagnetic scattering theory, are used to study and analyze in detail these surface morphologies. Combined with electron backscattering diffraction, analyses allow associating site-selectively various laser-induced-surface morphologies with the underlying crystalline grain orientation. Resulting grain orientation maps reveal a strong impact of the grain crystallographic orientation on LIPSS formation and point toward possible strategies, like multi-step processes, for improving the manufacturing of LIPSS and their areal coverage of polycrystalline technical materials.

Superconducting Nb thin films have been nanostructured by means of a femtosecond UV laser. Laser induced periodic surface structures (LIPSS) with lateral modulation of ≈ 250 nm and depth smaller than amplitude (≲ 20 nm from crest to trough) are obtained for optimized laser scanning conditions over the film surface, i.e. power, frequency, scanning speed and polarization. This provides a fast and scalable procedure of surface control at the nanoscale. In thin films, control over the kinetics of the LIPSS formation process has been crucial. Untreated and laser-patterned samples have been characterized by electron and atomic force microscopy as well as by local and global magnetometry. The superconducting properties reveal anisotropic behavior in accordance with the observed topography. The imprinted LIPSS define channels for anisotropic current flow and flux penetration. At low temperatures, magnetic flux avalanches are promoted by the increased critical current density, though flux tends to be channeled along the LIPSS. In general, directional flux penetration is observed, being a useful feature in fluxonic devices. Scalability allows us to pattern areas of the order of cm2/min.

This work studies the combination of direct femtosecond laser structuring of metal surfaces and Spatial Atomic Layer Deposition (SALD) of metal oxides as a novel approach to generate colours on different types of day-to-day metallic objects. In particular, a stainless-steel knife and an outdated 25 ct Dutch florin coin have been selected for the study. Our results show that it is possible both, to preserve the iridescence properties produced by laser processing and to tune the final metal surface colour by controlling the thickness of the ZnO coating. At the same time, this oxide coating could act as a protecting layer for the original material. We thus explore two different strategies to generate colour, namely, iridescence and interference, which can be even developed selectively. This novel methodology to colour metallic surfaces is a promising route to achieve cheap, scalable, and high-throughput processing methods and opens up a new avenue of possibilities and applications related to colour.

This work reports on studies aimed to evaluate the utilization of ultrashort 238 fs (fs) pulsed UV laser emission at 343 nm for eliminating colored crusts and surface deposits on significant Cretaceous flint surfaces, in an attempt to safeguard its aesthetic appearance and archaeological value. The results indicate that fs UV lasers may be an ideal, non-contact tool for selective surface cleaning of sensitive archaeological artefacts, since they enable contaminant desorption while avoiding photothermal damage.

The impact of wavelength and pulse duration in laser cleaning of hard blackish contaminants crust from archaeologically significant Pleistocene bone is investigated in this research. The objective is to determine the practical cleaning procedures and identify adequate laser parameters for cleaning archaeological bone from Sima de los Huesos (Spain) based on conservation and restoration perspectives. Bone surface cleaning was performed utilizing two Q-switched Nd:YAG lasers: sub-nanosecond pulsed lasers with emission wavelengths at 355 nm and 1064 nm, respectively, and a Yb:KGW femtosecond pulsed laser with an emission wavelength in the third harmonic at 343 nm. In all experiments, the laser beam scanning mode was applied to measure cleaning efficiency in removing contaminants and degradation products while assessing the underlying substrate surface damage. Several properties, including wavelength-dependent absorption, pulse repetition rate, and thermal properties of the material, are analyzed when evaluating the ability of these lasers to boost the cleaning efficiency of the deteriorated bone surface. Bone surface morphology and composition were studied and compared before and after laser irradiation, using Optical Microscopy, Scanning Electron Microscopy with Energy Dispersive X-ray Spectrometry (SEM-EDS), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Photoelectron Spectroscopy (XPS) characterization methods. The results indicate that 238-femtosecond UV laser irradiation with 2.37 TWcm−2 is significantly safer and more efficient toward surface contaminant desorption than sub-nanosecond laser irradiation. The results herein presented suggest that these types of fs lasers may be considered for realistic laser conservation of valuable historic and archaeological museum artifacts.

The aim of this research work was to conduct a comparative study on the effectiveness of the application of chemical cleaning versus laser cleaning in the removal of surface congruent dissolution products from a potash-lime–silica historical stained-glass sample. EDTA was selected as the chemical cleaning agent. Laser cleaning was performed using a 238 fs pulse UV (343 nm) laser. The comparative cleaning studies were carried out on a stained-glass piece supplied by the Maison Lorin Glass Restoration Workshop from Chartres, France. Given the complex nature, irregular thickness and heterogeneity of the encrustations found on the glass, the two cleaning approaches were carefully performed step by step, while monitoring the process using an optical microscope. Raman spectroscopy and field emission scanning electron microscopy were used to characterize the changes induced on the sample surface during the cleaning process. The results demonstrate that the two cleaning approaches were able to eliminate the outer surface dark layer associated with carbon compounds, as well as the external part of the white layer generated by the crystallization of salts, formed with the dissolved elements after a reaction with the air. A comparison of the advantages and disadvantages of each method is also presented.

Laser irradiation enables the removal of unwanted surface deposits from different materials in a safe and controllable manner. Laser parameters should be carefully selected to achieve the removal of the target contaminants without inducing damage to the substrate. Ultra-short pulse lasers have opened new opportunities for safe and controlled decontamination of cultural heritage materials because the thickness of material that is affected by the laser is limited. In this study, an ultraviolet femtosecond pulsed laser was used for the removal of unwanted encrustation formed on the surface of an historical colourless stained-glass sample from the Cuenca Cathedral in Spain. One of the sides of this glass exhibits a reddish-brown grisaille that also has to be preserved. A laser cleaning process has been designed to avoid heat accumulation while controlling the thickness of ablated material. In this context, a multi-step process was selected in order to be able to eliminate, in a controlled way, the crust layer without damaging the grisaille layer, or the glass substrate. In this case, laser irradiation in beam scanning mode with a pulse repetition frequency of 10 kHz proved to be effective for the safe cleaning of the glass. The latter was analysed before and after laser cleaning by optical and confocal microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray fluorescence, and Raman spectroscopy, confirming that the crust layer was effectively eliminated without damaging the surface.

Silver-doped graphite-like carbon (Ag-GLC) coatings were prepared on the surface of aluminum alloy and single-crystal silicon by magnetron sputtering under different deposition parameters. The effects of silver target current and deposition temperature, as well as of the addition of CH4 gas flow, on the spontaneous escape behavior of silver from the GLC coatings were investigated. Furthermore, the corrosion resistance of the Ag-GLC coatings were evaluated. The results showed that the spontaneous escape phenomenon of silver could take place at the GLC coating, regardless of preparation condition. These three preparation factors all had an influence on the size, number and distribution of the escaped silver particles. However, in contrast with the silver target current and the addition of CH4 gas flow, only the change in deposition temperature had a significant positive effect on the corrosion resistance of the Ag-GLC coatings. The Ag-GLC coating showed the best corrosion resistance when the deposition temperature was 500 °C, which was due to the fact that increasing the deposition temperature effectively reduced the number of silver particles escaping from the Ag-GLC coating

Due to the properties anisotropy exhibited by high temperature (HTc) superconductors, develop adqate processing technologies is a major challenge. Recently, the laser induced solidification techniques have been using to improve the microstructure of HTc superconductors namely, Bi2Sr2CaCu2O8+x (Bi-2212), REBa2Cu3O7-x (RE-123, RE=Y,Gd). Different laser technologies have been used to fabricate well-textured samples and to machine them without generating cracks. Texture has been controlled using a Laser Zone Melting (LZM) technique while the sample is at thigh temperature in a system calle Laser Furnace. This tecniue can be considered as a modification of the laser line scanning protocol. A very flat solidification front has been obtained in samples up to 100 mm wide. We have fabricated Bi-2212 superconducting samples up to 10cm x 10cm size. The flatness reached in the solidification front allows obtaining misorientation angles lower than 15º in the full width of the sample. The transport properties of these superconducting materials have been correlated with the level of texture and the thickness od the tectured region reached during the laser process. It can be argued that the size of the plate samples is adequate to desing several electrical circuits adapted for different applications.

Laser technology has gained significant attention over the past few decades, as an efficient, precise, and contactless tool for artworks conservation, along with a wider diffusion of applications in physical assessment and diagnoses techniques. However, within the paper conservation field, laser cleaning techniques remain at an experimental level, especially concerning pressuresensitive tape-damaged paper-based artworks. Despite their instability, pressure-sensitive tapes have long been used as a convenience aid and were often employed on artworks as a temporary solution for a multitude of purposes, like the fastening of loose parts, tear mends, or picture framing for exhibit purposes. Conventional conservation procedures are often not entirely satisfactory for minimizing persistent, sticky, and aesthetic obstructive stains from aged tapes on fragile, water-sensitive media. Additionally, they are difficult to control and essentially based on a trial error-based methodology, which results in further damage to the paper matrix and promotes health risks to the paper conservator, further emphasizing the value of research into the effects of laser cleaning on paper support. A Carbide model (Light Conversion) fs-pulsed laser operating at 1030 nm, 515 nm and 343 nm was employed to explore the cleaning of a set of different types of adhesive-stained papers with no patrimonial value. Macrophotography, optical and confocal microscopy, colorimetry, and FTIR spectroscopy techniques were used for the documentation and analytical characterization of the samples before and after the cleaning trials. Pulsed fs lasers have shown to significantly improve the cleaning results in comparison to nanosecond pulsed lasers with similar emission wavelengths. In addition, its ability for realtime monitoring of the cleaning progress, along with the possibility for better control of the laser parameters (pulse duration, frequency, pulse energy), is particularly relevant for the cleaning efficie

The Laser Furnace (LF) technology has been used to produce uniform, dense MnFe2O4 spinel disks from a mixture of Fe and Mn oxides for controlled synthesis of spinel nanoparticles via Laser Ablation. Application of a CO2 laser in Line Scan mode onto a sample with the desired stoichiometry, enabled melt processing above 1580ºC at its outer surface layer. In this process, a combination of a laser system and a continuous roller furnace operating at a maximum volume temperature of 1000ºC is used. Such combination helps avoid excessive thermal stress, crack formation and catastrophic failure of these magnetic ceramic monoliths. Higher energy incubation values yield increased molten volumes and a thicker resolidified surface layer with a dense microstructure. Despite the high solidification rates imposed, MnFe2O4 spinel is the main phase obtained according to X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and magnetization studies. LF processed samples exhibit a reduction of the coercive fields and an increase of the saturation magnetization values, evidence for soft ferromagnetism and characteristic of the magnetic behavior associated with this spinel. This work demonstrates the convenience of the LF method for preparation of uniform, dense targets for Laser Ablation and other evaporation based techniques used in the fabrication of nanoparticles.

Laser irradiation of transparent substrates in front of an absorbing target results in ablation of the target material and the consequent coating on the back of such substrate. The use of pulsed near-IR lasers is reviewed in this talk, with particular attention to coatings or surface modification produced on glass substrates. This method enables the fabrication of thin coatings on glass at low cost and without the need for vacuum or chemicals. It is thus attractive from the environmental and efficiency points of view. This relatively new fabrication method will be briefly presented and overviewed, and a number of examples analyzed in relation to the coatings obtained and types of lasers used.

Transition metal ferrite ceramics present very interesting magnetic properties, and are presently being considered in nanometric grain sizes for a number of applications in bioscience. Depending on the preferred transition metal for usage, these ferrite ceramics show stable melt behavior. Thus, they become ideal candidate materials for laser melt processing. Laser Zone Melting process provides many advantages, although until recently it was not possible to process large areas under controlled solidification conditions. These are necessary to exert a good degree of microstructure control. An effective solution to achieve a satisfactory directional solidification interface is found using Laser Line Scanning, where an instantaneous melting line is obtained on a substrate with a planar geometry. The resulting sharp melt-solid interface provides controlled microstructures and a stable melt on a moving material. In this particular case, the movable material is the preferred transition metal ferrite ceramic compact. Laser Line Scanning generates a dense compact on the machined surface that may be suitable for the subsequent production of nanoparticles with controlled properties via Laser Ablation. The purpose of present research is to focus on the evaluation of the microstructural and magnetic properties of nanoparticles of Mn ferrite spinel material fabricated via Laser ablation process.

Ice generation on the surface of wind generator blades can affect the performance of the generator in several aspects. It can deteriorate sensor performance, reduce efficiency, and cause mechanical failures. One of the alternatives to minimize these effects is to include passive solutions based on the modification of the blade surfaces, and in particular to generate superhydrophobic behavior. Ultra-short laser systems enable improved micromachining of polymer surfaces by reducing the heat affected zone (HAZ) and improving the quality of the final surface topography. In this study, a green fs laser is used to micromachine different patterns on the surface of materials with the same structure that can be found in turbine blades. Convenient optimization of surface topography via fs laser micromachining enables the transformation of an initially hydrophilic surface into a superhydrophobic one. Thus, an initial surface finish with a contact angle ca. 69° is transformed via laser treatment into one with contact angle values above 170°. In addition, it is observed that the performance of the surface is maintained or even improved with time. These results open the possibility of using lasers to control turbine blade surface microstructure while avoiding the use of additional chemical coatings. This can be used as a complementary passive treatment to avoid ice formation in these large structures.

[EN] Stained-glass windows form an important part of cultural heritage. Short pulse lasers open new opportunities for safe decontamination. In this work, and for the first time, the interaction of sub-nanosecond and femtosecond pulsed lasers with some contemporary stained-glasses has been analyzed exploring their applicability to safely clean stained-glass windows. The results show that, in these materials, damage can be induced using energy levels below damage thresholds due to the heat accumulation in the coating layer that is being eliminated. The latter generates significant thermal stresses on the glass volume, which induce crack formation. In consequence, in order to apply safe stained-glass cleaning protocols, laser parameters have to be selected to control the temperature increase within this layer. To achieve the latter goal, two alternative irradiation procedures were explored in this work. As a first option, a reduction of the effective pulse repetition frequency to values lower than 20 kHz was applied. A second alternative was used for lasers with pulse repetition rates in the hundreds of kHz. In this case, the burst mode was employed controlling the number of pulses emitted and combined with an adequate time lapse selection between two consecutive burst runs. A proof of concept demonstration was carried out on a stained-glass sample from the Cathedral of Cuenca, dated at the end of the XV century., [ES] Las vidrieras constituyen un elemento esencial de nuestro patrimonio cultural. Los láseres de pulsos ultracortos ofrecen nuevas oportunidades para desarrollar procesos de restauración seguros. En este trabajo, por primera vez, se estudia la interacción de láseres pulsados emitiendo pulsos en el rango de los subnanosegundos y femtosegundos con piezas de vidrieras contemporáneas, con el fin de explorar la posibilidad de desarrollar procesos seguros de restauración de vidrieras. Los resultados muestran que, en estos materiales, incluso trabajando con niveles de energía por debajo de los umbrales de daño, se puede generar deterioro por la acumulación de calor generada en la capa que se está eliminando, lo cual puede generar niveles de tensiones térmicas que provocan la ruptura del vidrio. Por tanto, para desarrollar protocolos de limpieza seguros, los parámetros de procesado deben escogerse de tal manera que se minimice la temperatura que se alcanza en esta capa. Se han explorado dos alternativas. Una es reducir la frecuencia de trabajo hasta valores por debajo de los 20 kHz. En el caso de láseres que trabajen a frecuencias más elevadas, la alternativa es trabajar en modo burst, limitando el número de pulsos en cada serie y estableciendo tiempos de espera entre dos series. Estas ideas se han aplicado sobre una pieza de vidriera de la Catedral de Cuenca de finales del siglo XV.

Nickel tungsten alloy tapes (Ni—5 at% W, 10 mm wide, 80 µm thick, biaxially textured) used in second-generation high temperature superconductor (2G-HTS) technology were laser-processed in air with ultraviolet ps-laser pulses (355 nm wavelength, 300 ps pulse duration, 250–800 kHz pulse repetition frequency). By employing optimized surface scan-processing strategies, various laser-generated periodic surface structures were generated on the tapes. Particularly, distinct surface microstructures and nanostructures were formed. These included sub-wavelength-sized highly-regular hexagonally-arranged nano-protrusions, wavelength-sized line-grating-like laser-induced periodic surface structures (LIPSS, ripples), and larger irregular pyramidal microstructures. The induced surface morphology was characterized in depth by electron-based techniques, including scanning electron microscopy (SEM), electron back scatter diffraction (EBSD), cross-sectional transmission electron microscopy (STEM/TEM) and energy dispersive X-ray spectrometry (EDS). The in-depth EBSD crystallographic analyses indicated a significant impact of the material initial grain orientation on the type of surface nanostructure and microstructure formed upon laser irradiation. Special emphasis was laid on high-resolution material analysis of the hexagonally-arranged nano-protrusions. Their formation mechanism is discussed on the basis of the interplay between electromagnetic scattering effects followed by hydrodynamic matter re-organization after the laser exposure. The temperature stability of the hexagonally-arranged nano-protrusion was explored in post-irradiation thermal annealing experiments, in order to qualify their suitability in 2G-HTS fabrication technology with initial steps deposition temperatures in the range of 773–873 K.

We report transport, electromechanical, and structural properties of single core MgB2/Fe wire produced using a new fabrication method, called designed internal Mg diffusion (IMD) process, which relies on the use of non-stoichiometric Mg + B pellets with excess Mg in place of a central Mg rod used in the standard IMD method. Structural analysis revealed the successful formation of a porous MgB2 structure in the center and a dense circular MgB2 layer surrounding this structure in the designed-IMD wire. Fast transport I–V measurements showed that the designed IMD method increased engineering critical current density (Je) up to twice that of the IMD wires in self-field. The central porous MgB2 structure shared the applied current and indirectly behaved as an internal stabilizer against quench damage at high applied currents.

The present invention relates to a method for modifying a vitreous material, a system suitable for carrying out said method, and the modified vitreous material that can be obtained by said method. This process improves the mechanical properties of the vitreous material. [EN], El objeto de la presente invención es un procedimiento de modificación de un material vítreo; un sistema adaptado para realizar dicho procedimiento y el material vítreo modificado obtenible mediante dicho procedimiento. Este proceso mejora las propiedades mecánicas del material vítreo. [ES]

Controlled laser irradiation parameters using recently developed sub-nanosecond pulsed laser technology with emission wavelength in the near Infrared regime (1064 nm) have been assessed on a Pleistocene bone from the archaeological site of Sierra de Atapuerca, Spain. Burst pulse mode was employed to explore contaminant removal efficiency, while at the same time, assessing the degree of damage produced to the underlying original substrate surface. The surface morphology and composition of the deteriorated bone have been characterized, along with the effects of laser irradiation at 1064 nm, using Optical Microscopy (OM), Scanning Electron Microscopy–with Energy Dispersive X-ray Spectrometry (SEM–EDS), and X-ray Photoelectron Spectroscopy (XPS). The most effective laser cleaning parameters in burst mode have been identified in order to optimize the emission parameters of the laser, thus localizing its interaction within the outermost layers of contaminants and degradation products, avoiding damage to the underlying original bone surface. Hence, threshold cleaning and substrate damage values have been determined for this new sub-ns laser, paving the way to safer laser cleaning procedures that may be useful for the effective conservation of bone archaeological artifacts.

The objective of this work is the enhancement of metal-to-metal bonding to provide high thermal conductivity together with electrical insulation, to be used as heat sinks at room and cryogenic temperatures. High thermal conductive metal (copper) and epoxy resin (Stycast 2850FT) were used in this study, with the latter also providing the required electrical insulation. The copper surface was irradiated with laser to induce micro- and nano-patterned structures that result in an improvement of the adhesion between the epoxy and the copper. Thus, copper-to-copper bonding strength was characterized by means of mechanical tensile shear tests. The effect of the laser processing on the thermal conductivity properties of the Cu/epoxy/Cu joint at different temperatures, from 10 to 300 K, is also reported. Using adequate laser parameters, it is possible to obtain high bonding strength values limited by cohesive epoxy fracture, together with good thermal conductivity at ambient and cryogenic temperatures.

A pulsed laser ablation backwriting technique with high repetitive rates is implemented for the fabrication of silver coatings on glass surfaces. This method enables geometrical constraint-free deposition of metallic coatings. These exhibit sufficiently low electrical resistance to be used as electrodes in dielectric barrier discharge (DBD) plasma elements. Ambient air deposition of metallic silver electrodes on standard glass slides is explored using a sub-ns UV laser source, combined with hybrid beam scanning methods. The green nature of the overall deposition process includes a preliminary irradiation scan to homogenise the target surface before the subsequent backwriting step. Metal transfer is achieved by combining two phenomena within a simple beam scanning process: LIRT (laserinduced reverse transfer) of silver from the target to the glass, with a partial and secondary LIFT (Laser-Induced Forward Transfer) of silver from the glass to the target. Appropriate selection of pulse energy and pulse repetition rates, beam scanning velocities and target motion enable the growth of sufficiently thick Ag deposits on glass with the required low electrical resistivity and nearly 2D constraint-free geometry. This method avoids the use of vacuum and liquids, resulting in a cheap, facile and green methodology for the deposition of silver electrodes onto transparent substrate surfaces.

The Laser Floating Zone (LFZ) technique, also known as Laser-Heated Pedestal Growth (LHPG), has been developed throughout the last several decades as a simple, fast, and crucible-free method for growing high-crystalline-quality materials, particularly when compared to the more conventional Verneuil, Bridgman–Stockbarger, and Czochralski methods. Multiple worldwide efforts have, over the years, enabled the growth of highly oriented polycrystalline and single-crystal high-melting materials. This work attempted to critically review the most representative advancements in LFZ apparatus and experimental parameters that enable the growth of high-quality polycrystalline materials and single crystals, along with the most commonly produced materials and their relevant physical properties. Emphasis will be given to materials for photonics and optics, as well as for electrical applications, particularly superconducting and thermoelectric materials, and to the growth of metastable phases. Concomitantly, an analysis was carried out on how LFZ may contribute to further understanding equilibrium vs. non-equilibrium phase selectivity, as well as its potential to achieve or contribute to future developments in the growth of crystals for emerging applications.

The main objective of this study is to investigate the structural features, magnetic behaviour, photocatalytic properties and blood compatibility of NiFe2O4 nanoparticles (NPs) obtained by subnanosecond laser ablation in water. Structure and size distribution of NPs were studied using X-Ray Diffractometry (XRD) and Transmission Electron Microscopy (TEM). The photocatalytic properties of NPs were evaluated by photo-degradation of Methylene Blue (MeB) dye under ambient visible light illumination. Four different kinetic models were used to identify the photocatalytic degradation mechanism of NiFe2O4 nanoparticles and it was found that the pseudo-second-order model was the most suitable type to interpret the experimental kinetic data of MeB photodegradation. The hemocompatibility of NiFe2O4 nanoparticles was studied by hemolysis tests using human erythrocytes drawn from healthy volunteers. NiFe2O4 nanoparticles caused undesirable hemolysis ratios at 0.05, 1 and 5 mg/ml concentrations, while the biologically safe concentration of these nanoparticles was found to be below 0.01 mg/ml.

Un horno continúo 4 al que se le acopla un láser por medios ópticos convencionales que permite el tratamiento superficial de una pieza, con el que se pueden alcanzar en dicha superficie temperaturas de hasta 3000°C, mientras que en el resto de la pieza la temperatura es sensiblemente inferior. La pieza en el horno se calienta a una temperatura del orden de los 500°C y por una apertura 5se hace llegar a la pieza un haz de rayos láser que barre una línea perpendicular a la dirección de su movimiento de forma que elbarrido de toda la superficie se consigue mediante el avance mecánico de la pieza. Este barrido debe superar los extremos laterales de la pieza. El tipo de generador de rayo láser debe hacerse compatible con los diferentes colores que decoran la superficie dela pieza. El horno está dividido en diferentes zonas, con controles de temperatura independientes, para conseguir alcanzar los valores deseados, tanto de calentamiento como de enfriamiento. El sistema generador de radiación láser y su deflector comprende /a cavidad de generación y emisión de radiación (láser de CO2, en torno a los 10,6 µm, o los láseres de diodos o de Nd en sus diferentes variedades) y el sistema de manipulación de haz emitido, que puede hacerse por un sistema de galvanómetros o por una serie de combinaciones de lentes para conseguir dar forma al haz e incidir de la manera adecuada al tipo de proceso, material tratado y láserempleado.

Irradiation with ultra-short (femtosecond) laser beams enables the generation of sub-wavelength laser-induced periodic surface structures (LIPSS) over large areas with controlled spatial periodicity, orientation, and depths affecting only a material layer on the sub-micrometer scale. This study reports on how fs-laser irradiation of commercially available Nb foil samples affects their superconducting behavior. DC magnetization and AC susceptibility measurements at cryogenic temperatures and with magnetic fields of different amplitude and orientation are thus analyzed and reported. This study pays special attention to the surface superconducting layer that persists above the upper critical magnetic field strength Hc2, and disappears at a higher nucleation field strength Hc3. Characteristic changes were distinguished between the surface properties of the laser-irradiated samples, as compared to the corresponding reference samples (non-irradiated). Clear correlations have been observed between the surface nanostructures and the nucleation field Hc3, which depends on the relative orientation of the magnetic field and the surface patterns developed by the laser irradiation.

The Laser Furnace (LF) method has been applied to directionally solidify NiFe2O4 spinel disks from a mixture of Fe and Ni oxides in order to obtain uniform, dense targets for controlled synthesis of spinel nanoparticles via Laser Ablation. Application of a CO2 laser in Line Scan mode onto a sample with the desired stoichiometry, enabled melt processing above 1580 °C at its outer surface layer. This process was carried out inside a continuous roller furnace at a maximum volume temperature of 1000 °C. Such combination helps avoid excessive thermal stress, crack formation and catastrophic failure of these magnetic ceramic monoliths. Higher energy incubation values yield increased molten volumes and a thicker resolidified surface layer with a dense microstructure. Despite the high solidification rates imposed, NiFe2O4 spinel is the main phase obtained according to X-Ray Diffraction (XRD) and magnetization studies. LF processed samples exhibit a reduction of the coercive fields and an increase of the saturation magnetization values, evidence for soft ferromagnetism and characteristic of the magnetic behaviour associated with this spinel. This work demonstrates the convenience of the LF method for preparation of uniform, dense targets for Laser Ablation and other evaporation based techniques used in the fabrication of nanoparticles.