Francisco Javier Palomares

Francisco Javier Palomares
Spanish National Research Council | CSIC · Instituto de Ciencia de Materiales de Madrid

PhD. Physics

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184
Publications
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2,802
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Publications

Publications (184)
Article
Full-text available
Surface nanopatterning induced by ion beam irradiation (IBI) has emerged as an effective nanostructuring technique since it induces patterns on large areas of a wide variety of materials, in short time, and at low cost. Nowadays, two main subfields can be distinguished within IBI nanopatterning depending on the irrelevant or relevant role played by...
Article
Full-text available
The use of magnetic nanoparticles in C–C coupling reactions enables the facile recovery of the catalyst under environmentally friendly conditions. Herein, the synthesis of Pd/Fe@Fe 3 O 4 nanoparticles by the reduction of Pd ²⁺ and oxidation of Fe on the surface of preformed Fe@Fe 3 O 4 is reported. The nanoparticles were characterized using a varie...
Article
Full-text available
We report on the measurement of the local magnetization dynamics occurring, at units of GHz, in large aspect ratio stripes lithographed from reduced damping amorphous Fe80B20 films. The stripes were submitted to local anisotropy modifications by micrometric beam synchrotron X-ray irradiation. Our results include data on the dispersion relationships...
Article
Full-text available
Gallium nanoparticles (Ga NPs) are attracting increasing attention because of their appealing physical-chemical properties. In particular, their mechanical properties play a key role in the implementation of these core-shell structures on certain applications, such as soft and stretchable electronics. Thus, efforts are being addressed to modulate t...
Article
We investigate the low temperature magnetic behavior of three epitaxial Co/Ag multilayers, grown onto MgO (001) substrates, with a nominal content per period of either half a monolayer or one monolayer of Co, and either 8 or 16 Ag monolayers. The samples were studied by X-ray reflectivity and diffraction, transmission electron microscopy, magnetome...
Article
In this work we study the crystallization processes of two sets of amorphous Fe80B20 films fabricated by Pulsed Laser Ablation Deposition on substrates with different nature, Corning glass® and MgO(001). We analyze their magnetic hysteresis mechanisms by means of magneto-optic techniques and Transmission Electron Microscopy. The as-deposited amorph...
Article
We report on the temperature dependence of the interactions present in single crystal magnetite nanoparticles having octahedral and spherical morphologies. From our results we conclude that the inter-particle interactions are, at all temperatures and in both octahedral and spherical nanoparticles, demagnetizing in nature. These interactions are not...
Article
We report on the effect, on the local magnetization reversal taking place in amorphous Fe80B20 stripes, of the irradiation with nanobeam synchrotron X-ray. That irradiation preserves the amorphous structure and results on the increase of the local coercivity with respect to that measured in a non-irradiated sample, in which the coercivity is mediat...
Article
We studied the adsorption/degradation process of methylene blue in a Fenton like process using iron oxide nanoparticles as a source of Fe²⁺ ions, where the nanoparticles were prepared via a facile electrochemical synthesis method. The degradation kinetics were studied using 2 g L⁻¹ of catalyst and 100 ppm of pollutant at pH 3.5. The influence of te...
Article
We study the nanopatterning of silicon surfaces under near-normal 40-keV Ar+ sputtering with simultaneous Fe oblique codeposition. The ion-beam incidence was kept at 15°, for which no pattern is produced in the absence of metal incorporation. Morphological and compositional analyses were performed by atomic force microscopy, in its morphological an...
Article
We report on the induction, through X-ray irradiation, of local anisotropy modifications in amorphous Fe80B20 stripes prepared by laser lithography from 15 nm thick films deposited by pulsed laser ablation. Those anisotropy modifications, taking place in a zone having a dimension of 15 μm around the X-ray beam (2 µm width) incidence area center poi...
Article
Full-text available
Due to its extraordinary properties, the C12A7:e⁻ electride has been suggested in the past as one of the most promising materials for coating Low Work-function Tethers (LWTs). Such subclass of electrodynamic tether, made of a conductive substrate coated with materials that enhance the electron emission through the thermionic and photoelectric effec...
Article
The solid state reaction between kaolin and Li2CO3 with a 1:1 M composition has been studied in the temperature range 380ºC-550 °C. The role played by Li2CO3 (basic medium) in the thermal transformation of the kaolin has been investigated by X-Ray diffraction, SEM, TEM, MAS-NMR and XPS techniques. For the first time, a nanostructured high density β...
Article
The non-covalent radiolabelling of new graphene oxide-bis(thiosemicarbazonato) nanohybrids with gallium-68 and zirconium-89 ions is reported herein for the first time.
Article
Full-text available
We report on the design and testing of new graphite and graphene oxide‐based extended π‐conjugated synthetic scaffolds for applications in sustainable chemistry transformations. Nanoparticle‐functionalised carbonaceous catalysts for new Fischer Tropsch and Reverse GasWater Shift (RGWS) transformations were prepared: functional graphene oxides emerg...
Article
Anatase TiO2 has become a material of great interest for photocatalytic production of hydrogen, environmental purification and solar energy conversion. Among the key parameters boosting the photocatalytic efficiency of the anatase nanoparticles, an increased light absorption to expand its optical response to the visible region, together with an imp...
Article
Full-text available
We present a ferromagnetic resonance study of the dynamic properties of a set of amorphous Fe-B films deposited on Corning Glass® and MgO (001) substrates, either with or without capping. We show that the in plane anisotropy of the MgO grown films contains both uniaxial and biaxial components whereas it is just uniaxial for those grown on glass. Th...
Article
We report on the magnetization reversal measured in two ferromagnetic/antiferromagnetic (F/AF) bilayer series: Fe/NiO/Al2O3 (nanoporous membranes, series N) and Fe/NiO/Si (wafers, series W). The Fe and NiO layers were deposited by pulsed laser ablation and magnetron sputtering, respectively. In both series different oxygen partial pressures were im...
Article
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Three-dimensional fluorescent graphene frameworks with controlled porous morphologies are of significant importance for practical applications reliant on controlled structural and electronic properties, such as organic electronics and photochemistry. Here we report a synthetically accessible approach concerning directed aromatic stacking interactio...
Article
We report on the low temperature magnetic behavior of an epitaxially grown multilayer formed by 32 repetitions of a nominal period corresponding to 1 monolayer (ML) Co and 16 ML Ag. The study of the magnetic properties was based on the measurement of the temperature dependencies of the dc magnetization upon field cooling (FC) and zero field cooling...
Article
Thermally activated relaxation over energy barriers concurrently related to local properties and interparticle interactions constitutes a major contribution to both the coercivity and the applied field frequency dependence of that quantity. We have measured the slow magnetic relaxation of magnetite nanoparticles (NPs), synthetized by using the oxid...
Article
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Silicon‐based materials are needed in cutting‐edge technological fields, for which hierarchical porosity and photonic properties help improve performance. In this work, the versatility of several fabrication routes that combine silicon infiltration by chemical vapor deposition (CVD), reactive ion etching (RIE), and carbon calcination, which produce...
Article
Full-text available
Magnetite nanoparticles (Fe3O4) of 12 ± 4 nm diameter are electrochemically synthesized for the adsorption and magnetic harvesting of Cr(VI) from contaminated simulated solutions. The removal of Cr(VI) from aqueous media follows pseudo-second-order kinetics. The adsorption efficiency is evaluated in three different scenarios. In standard conditions...
Article
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In this paper, we report on the phase selectivity in Cr and N co-doped TiO2 (TiO2:Cr,N) sputtered films by means of interface engineering. In particular, monolithic TiO2:Cr,N films produced by continuous growth conditions result in the formation of a mixed-phase oxide with dominant rutile character. On the contrary, modulated growth by starting wit...
Article
Full-text available
The ageing of graphene is an important issue for technological applications. Capping layers are a good way of circumventing this problem. In this work, we propose the use of ultra-thin NaCl films as easily-removable protective layers. We have carried out a detailed characterization of the NaCl/graphene interface on metal substrates, namely Cu(111)...
Article
With the aim of achieving stable, substantial remanences adequate for exploitation in stray field-based applications, we report on the hysteresis behavior occurring in arrays of single-crystal Fe motifs, e-beam lithographed into prisms with triangular bases and different orientations of their magnetocrystalline axes with respect to the morphologica...
Article
Direct, robust, and high-resolution patterning methods are needed to downscale the lateral size of two-dimensional materials to observe new properties and optimize the overall processing of these materials. In this work, we report a fabrication process where the initial microchannel of a few-layer WSe2 field-effect transistor is treated by oxygen p...
Article
Neural diseases at the central nervous system including spinal cord injury (SCI) remain therapeutic challenges. Graphene materials are being delineated as alternative tools for neural repair. Herein, the regenerative ability of reduced graphene oxide (rGO) scaffolds to support pivotal features of neural repair at 4 months after SCI is assessed by a...
Article
Alpha-1-acid glycoprotein (AGP) is a serum glycoprotein whose levels are increased two or three times during disease or injury. This makes it a potential biomarker for inflammatory bowel diseases and sepsis. Consequently, fast, simple, and cheap analytical methods for prognosis, diagnosis, and follow-up of these diseases are demanded. In this work,...
Poster
Full-text available
Over the past decades, semiconductor photocatalysts have long been studied due to their potential application in a wide range of fields such as removal of toxic pollutants and photocatalytic water splitting. In this sense, current research endeavors in the field of semiconductor photocatalysts are widely focused on the sustainable production of TiO...
Article
Core-shell gallium nanoparticles (Ga NPs) have recently been proposed as an ultraviolet plasmonic material for different applications but only at room temperature. Here, the thermal stability as a function of the size of the NPs is reported over a wide range of temperatures. We analyse the chemical and structural properties of the oxide shell by x-...
Article
We have bombarded crystalline silicon targets with a 40 keV Fe+ ion beam at different incidence angles. The resulting surfaces have been characterized by atomic force, current-sensing and magnetic force microscopies, scanning electron microscopy, and x-ray photoelectron spectroscopy. We have found that there is a threshold angle smaller than 40° fo...
Article
Compositional changes taking place during the synthesis of alloyed CdSeZnS nanocrystals (NCs) allow shifting the optical features to higher energy as the NCs grow. Under certain synthetic conditions, the effect of those changes on the surface/interface chemistry competes with and dominates over the conventional quantum confinement effect in growing...
Article
The surface morphology of molybdenum silicide (Mo<sub>x</sub>Si<sub>1-x </sub>) films has been studied after low-energy Ar<sup>+</sup> ion-beam sputtering (IBS) to explore eventual pattern formation on compound targets and, simultaneously, gather information about the mechanisms behind silicide-assisted nanopatterning of silicon surfaces by IBS. Fo...
Article
The effect of the oxidation of gallium nanoparticles (Ga NPs) on their plasmonic properties is investigated. Discrete dipole approximation has been used to study the wavelength of the out-of-plane localized surface plasmon resonance (LSPR) in hemispherical Ga NPs, deposited on silicon substrates, with oxide shell (Ga2O3) of different thickness. The...
Article
Carbon black nanoparticles (CBNPs) press imprinted films are proposed for class-selective electrochemical detection of ortho-diphenols (o-diphenols) and mono-phenols (m-phenols) antioxidants. In order to optimize the sensor construction, different surface immobilizations of CBNPs electroactive films on a PMMA support were assayed by using different...
Article
Graphene functionalization with organics is expected to be an important step for the development of graphene-based materials with tailored electronic properties. However, its high chemical inertness makes difficult a controlled and selective covalent functionalization, and most of the works performed up to the date report electrostatic molecular ad...
Data
Supplementary Figures, Supplementary Tables, Supplementary Notes, Supplementary Methods and Supplementary References
Article
The gas phase synthesis and characterization of multifunctional core@shell, Au@TiOx nanoparticles is reported. The nanoparticles are produced in a one-step process by using a Multiple Ion Cluster Source under controlled environment that guaranties the purity of the nanoparticles. The growth of the Au cores (6 nm diameter) is stopped when these latt...
Article
The generation of intense electron beams with low emittance is key to both the production of coherent x rays from free electron lasers, and electron pulses with large transverse coherence length used in ultrafast electron diffraction. These beams are generated today by photoemission from disordered polycrystalline surfaces. We show that the use of...
Article
Full-text available
The dissolution of an antimicrobial ZnO-glass in the form of powder and in the form of sintered pellets were studied in water, artificial seawater, biological complex media such as common bacterial/yeast growth media (Luria Bertani (LB), yeast extract, tryptone), and human serum. It has been established that the media containing amino acids and pro...
Article
We have produced self-organised silicide nanodot patterns by medium-energy ion beam sputtering (IBS) of silicon targets with a simultaneous and isotropic molybdenum supply. Atomic force microscopy (AFM) studies show that these patterns are qualitatively similar to those produced thus far at low ion energies. We have determined the relevance of the...
Article
We have deposited 4-aminophenol on Pt(111) surfaces in ultra-high vacuum and studied the strength of its adsorption through a combination of STM, LEED, XPS and ab initio calculations. Although an ordered (2√3×2√3)R30º phase appears, we have observed that molecule-substrate interaction dominates the adsorption geometry and properties of the system....
Article
Well-dispersed magnetite nanoparticles of different sizes between 15 and 43 nm were synthesized by an electrochemical method in a controlled manner by simply changing the synthesis temperature. These nanoparticles were used as a reusable adsorbent to remove Cr(VI) from aqueous solution. The recovery efficiency was found to be highly dependent on en...
Article
Full-text available
The occurrence of ferro-antiferromagnetic (F/AF) interfaces in Fe/NiO bilayers brings about the possibility of controlling the Fe layer hysteretic properties through the unidirectional anisotropy induced by the presence of unbalanced, antiferromagnetic phase moments at that interface. In this work, we report on the Fe thickness and temperature depe...
Article
Full-text available
Samples of nominal composition Li1.3Fe0.3Ti1.7(PO4)3 with a NASICON-type crystal structure, can be sintered up to 95% of the theoretical density at only 600°C using spark plasma sintering, SPS. The final pellets however show different colouration in their upper and lower faces, being the upper face white and the lower one pink. The analysis of both...
Article
Full-text available
We report the growth of europium sesquioxide (Eu2O3) thin films by pulsed laser deposition (PLD) in vacuum at room temperature from a pure Eu2O3 ceramic bulk target. The films were deposited in different configurations formed by adding capping and/or buffer layers of amorphous aluminum oxide (a-Al2O3). The optical properties, refractive index and e...
Article
An effective synthesis strategy for the extensive fluorination of the TiO2 anatase lattice has been developed which provides a highly stable blue-colored titania powder. The process also produces a convenient faceted morphology of the doped nanoparticles. Both theoretical and experimental data indicate an ordered atomic structure, in which an excep...
Article
Magnetic, chemical and structural properties of electrosynthesized CoxNi100 -x have been studied. The electrodeposition has been conducted both in the presence and absence of a low magnetic field. The application of a perpendicular magnetic field during the synthesis modified slightly the morphology of the alloys. These changes depend more on the f...
Article
Direct sublimation of a Cu4Cl4 metal-organic cluster on Cu(110) in ultra-high vacuum allows the formation of ultra-large well-organized metal-organic supramolecular wires. Our results show that the large monomers assemble to each other by π−π interactions connecting dipyrimidine units and are stabilized by the surface.
Article
We address the impact of metal co-deposition in the nanodot patterning dynamics of Si(100) surfaces under normal-incidence 1 keV Ar(+) ion-beam sputtering (IBS). In particular, the effect of both the metal nature (Fe or Mo) and flux has been studied. Morphological and compositional evolution were followed by atomic force microscopy (AFM) and Ruther...
Article
CoNi alloys including Co30Ni70, Co50Ni50 and Co70Ni30 were prepared via mechanical alloying using Co and Ni powders. The crystallinity and short-range order were studied using X-ray diffraction and X-ray absorption spectroscopy. The results show that the milling process increases the number of vacancies, especially around the Co atoms, while the mi...
Article
Full-text available
Ion beam patterning of a nanoscale ripple surface has emerged as a versatile method of imprinting uniaxial magnetic anisotropy (UMA) on a desired in-plane direction in magnetic films. In the case of ripple patterned thick films, dipolar interactions around the top and/or bottom interfaces are generally assumed to drive this effect following Schlöma...
Article
Full-text available
In this work, we improve the ability to tailor the switching mechanism in nanomagnets by introducing an additional, highly controlled source of anisotropy: magnetocrystalline anisotropy. We analyze the vortex dynamics in single crystal Fe nanotriangles with different orientations of the crystalline axes. By experimental studies and simulation, we s...
Article
Full-text available
Fluorine species adsorbed on the surface of TiO2 anatase nanoparticles improve their photocatalytic performance by reducing the recombination rate of photogenerated electrons and holes. Trifluoroacetic acid (TFAA) has been recently proposed as a promising harmless substitute for hydrofluoric acid (HF) in preparing fluorine-modified anatase with goo...
Article
Cadmium telluride (CT) and Zn-doped (∼4 at%) CT (CZT) crystals grown by the Bridgman method were mechanically polished to achieve mirror-like surfaces and subsequently irradiated with medium-energy (30–200 keV) Ar + ions under oblique incidence (60° with respect to the target normal). Atomic force microscopy shows that ion sputtering induces the fo...
Article
Laser driven plasma light sources offer highly intense output in the UV-visible region combined with a source size as small as 100 μm. In order to effectively use the small source size in high brightness applications, a stigmatic monochromator and focusing system must be used. Here we describe a simple brightness preserving optical system that shou...
Article
The magnetic phase transitions for Gd(0 0 0 1) grown on W(1 1 0) – a bulk transition at 293 K and a surface transition about 85 K above this – are found to influence the energy separation of the Gd 5s and 4s core-photoelectron doublets. The 5s doublet separation ΔE5s changes over a range of temperatures spanning these transitions, and decreases by...
Article
The biofilm formation of a strain of the extremophile bacterium Acidiphilium sp., capable of donating electrons directly to electrodes, was studied by different surface characterization techniques. We develop a method that allows the simultaneous study of bacterial biofilms by means of fluorescence microscopy and atomic force microscopy (AFM), in w...