New publication: Evolution of the structural and optical properties of La doped silver niobate-based thin films

Publicada el 1 septiembre, 2025 por agullo

Y. Mendez-González, J.D.S. Guerra, F. Agulló-Rueda, O. Peña‐Rodríguez, A. Fernández García, M. Manso Silvan, «Evolution of the structural and optical properties of La doped silver niobate-based thin films,» Mater. Sci. Eng. B 323A, 118667 (2025).

A detailed investigation on the structural and optical properties was conducted in lanthanum-substituted Ag(Nb0.80Ta0.20)O3 (ALNTx) thin films with La3+ concentrations of x = 0, 0.01, 0.02, and 0.03, prepared via chemical solution deposition process. X-ray diffraction confirmed the formation of a polycrystalline perovskite phase (orthorhombic, Pb21m) in all compositions, alongside minor Ag and Ag2O secondary-phases at low La levels. Raman spectroscopy revealed a progressive increase in the active vibrational modes with La doping, reaching up to 19 modes for the compositions with x = 0.02 and 0.03. In particular, the M1 band (at 108–110 cm-1) emerges only at these higher dopant levels, along with the progressive appearance of additional modes in the 550–950 cm-1 region (identified as M13–M19) as the La-content increases, indicating enhanced local structural distortion and NbO6 octahedral tilting. RBS analysis confirmed homogeneous stoichiometry and film thicknesses ranging from 4.4 × 1017 to 7.0 × 1017 atoms/cm2. Optical measurements revealed an indirect bandgap narrowing from 3.50 eV (undoped) to 2.81 eV (x = 0.02), driven by lattice distortion, local bonding changes and reduced Ag/La–O hybridization. The findings demonstrate that the La doping is an effective strategy for tuning the structural and optical properties of Ag(Nb,Ta)O3 thin films, making them attractive for integration into specialized optoelectronic applications, such as functional layers in tandem or multilayer energy devices.

Publicado en nanocharacterization, Raman spectroscopy, transition metal oxides | Etiquetado , , , , , , | Comentarios desactivados en New publication: Evolution of the structural and optical properties of La doped silver niobate-based thin films

New publication: Microstructural effects of thermal annealing in GaInNAsSb epitaxial layers

Publicada el 24 julio, 2025 por agullo

M. Gabás, A. Landa-Cánovas, J. Santiso, I. Lombardero, I. García, N. Miyashita, Y. Okada, P. F. Palacios, C. Algora, «Microstructural effects of thermal annealing in GaInNAsSb epitaxial layers,» J. Alloys Compd. 10137, 182315 (2025)

A set of dilute nitride GaInNAsSb epitaxial layers, some of them submitted to a thermal treatment, has been studied in this work in order to elucidate the microstructural changes induced by annealing. Two semiconductor structures consisting in a GaInNAsSb layer with two different thicknesses, 0.2 and 1 μm, sandwiched between GaAs layers, were grown on GaAs substrates. Three pieces of each structure were studied: one was left as-grown, another one was submitted to a rapid thermal annealing (RTA), and the third one to a longer annealing in a Metal Organic Vapor Phase Epitaxy (MOVPE) reactor. The objective was to compare the GaInNAsSb layer microstructure before and after each thermal treatment, as a function of the dilute nitride layer thickness. The composition profile of the samples and their variations with annealing have been determined using secondary ion mass spectrometry. X-ray diffraction techniques have been used to explore each layer crystalline quality, the lattice mismatch, and the strain. High resolution transmission electron microscopy tools have allowed to establish a quantitative comparison among the samples in terms of misfit dislocations density. Our results indicate that the effect that each annealing has on the microstructure of these GaInNAsSb layers is dependent on the initial state of the as-grown samples. RTA has a limited effect on these layers, while the MOVPE annealing induces noticeable changes in its microstructure.

Publicado en diluted nitrides, HRTEM, microscopy, nanoscience, nanotechnology, Publications, semiconductor | Etiquetado , , , , | Comentarios desactivados en New publication: Microstructural effects of thermal annealing in GaInNAsSb epitaxial layers

New publication: Thermal shock resistance of additive manufactured Inconel 718 by concentrated solar energy

Publicada el 22 mayo, 2025 por agullo

J. de Damborenea, A. Conde, G. P. Rodriguez-Donoso, F. Agulló-Rueda, and M. A. Arenas, «Thermal shock resistance of additive manufactured Inconel 718 by concentrated solar energy,» Sci. Rep. 15, 7557 (2025).

Concentrated Solar Power (CSP) is a powerful tool for simulating the extreme high-temperature conditions that metallic materials encounter. Using a vertical parabolic solar furnace, it was possible to perform heating and cooling cycles between 250 and 950 °C in approximately 250 s per cycle. This capability is particularly relevant for the development of solar receivers used in solar thermal plants. Additive Manufacturing (AM) offers the potential to create new compositions and geometries that can enhance the efficiency of these solar receivers. In this study, Ni-base superalloys—identified as suitable materials for high-temperature solar receivers—were produced using AM and tested in two conditions: as-built and after thermal treatment. These were compared with a forged reference alloy. The results revealed the formation of a protective oxide layer on the surface in all cases. However, the oxide layer on the samples fabricated by additive manufacturing appeared to be more compact and adherent compared to that formed on the reference alloy.

 

Publicado en microscopy, nanocharacterization, nanoscience, nanotechnology, Publications, Raman spectroscopy | Etiquetado , , | Comentarios desactivados en New publication: Thermal shock resistance of additive manufactured Inconel 718 by concentrated solar energy

New publication: Silicon amorphization responses by combined irradiations with MeV ion beams and ultrashort laser pulses

Publicada el 22 mayo, 2025 por agullo


I. Solana, M. Dolores Ynsa, F. Agulló-Rueda, J. Sánchez-Prieto, D. Grojo, J. Siegel, M. Garcia-Lechuga, «Silicon amorphization responses by combined irradiations with MeV ion beams and ultrashort laser pulses,» Surf. Interfaces 69, 106772 (2025).

This work demonstrates a significant synergistic effect between MeV ion implantation and femtosecond laser irradiation in silicon amorphization. The achievable amorphization depth and the range of laser fluencies leading to amorphization is increased for implanted samples in comparison to pristine silicon. In Si(100) samples, prior to femtosecond laser irradiation (800 nm and 120 fs, or 1030 nm and 180 fs) ion-induced defects are produced with protons (0.6, 1 and 2 MeV) or Si-ions (2 MeV) at varying ion-irradiation fluences. Then, the investigated defects densities before laser irradiation range from low levels to levels approaching ion-induced amorphization (defects per atom, dpa, from 10-9 to 0.1). The optimal pre-conditioning for subsequent femtosecond laser-induced amorphization is found at a moderate defect density level, dpa =10-5. Additionally, it is shown that the achievable spatial resolution of the synergistic material amorphization is determined by the high resolution of the focused ion irradiation, suggesting a potential pathway for high-resolution patterning based on laser-assisted techniques. However, at high defect densities (dpa ≈ 0.1), the synergistic effect diminishes, and femtosecond laser irradiation instead reduces disorder, indicating a defect-annealing effect rather than further amorphization.

Publicado en femtosecond-pulsed laser irradiation, ion irradiation, Publications, Raman spectroscopy, semiconductor, silicon, Sin categoría | Etiquetado , , , , , | Comentarios desactivados en New publication: Silicon amorphization responses by combined irradiations with MeV ion beams and ultrashort laser pulses

Director’s Team Seminar: A New Microscope in the Neighborhood by Ángel Landa

Publicada el 7 mayo, 2025 por agullo
Seminar A New Microscope in the Neighborhood

Seminar announcement: A New Microscope in the Neighborhood by Angel Landa

During the last decade new advances in electron microscopy are producing a revolution in transmission electron microscopy. This new developments in Transmission Electron Microscopy (TEM) and scanning TEM (STEM) are pushing the boundaries of nanoscale imaging and analysis, offering enhanced capabilities for materials science, biology, and other fields. Here are some key trends and recent advancements:

New developments in Scanning Transmission Electron Microscopy (STEM) are pushing the boundaries of nanoscale imaging and analysis, offering enhanced capabilities for materials science, biology, and other fields. Here are some key trends and recent advancements:
Advancements in Hardware and Software

  • Improved Resolution: Aberration-corrected STEMs are achieving sub-angstrom resolution, allowing researchers to visualize individual atoms and their arrangements with unprecedented clarity. The integration of Cold FEGs into new STEM instruments provides several key benefits that enhance their performance and capabilities: High Brightness and Small Energy Spread.
  • Faster Imaging and Data Acquisition: New detector technologies and advanced data acquisition architectures enable faster and more sensitive imaging. This allows for the capture of dynamic processes and the acquisition of richer datasets in a shorter time.
  • Enhanced Automation: Modern STEM platforms incorporate sophisticated automation features to streamline complex workflows, including alignment, calibration, and data acquisition. This improves ease of use and reduces the time required for experiments.
  • Multi-Modal Analysis: Current STEM instruments often integrate multiple analytical techniques, such as Energy-Dispersive X-ray Spectroscopy (EDS) and Electron Energy Loss Spectroscopy (EELS), allowing for simultaneous acquisition of structural, chemical, and electronic information at the nanoscale.
  • Direct Electron Detectors (DEDs): These detectors, increasingly used in STEM, record movies of the sample rather than still images, allowing for the correction of beam-induced motion and resulting in higher resolution and improved signal-to-noise ratios.

In summary, the field of STEM is rapidly evolving with significant advancements in hardware, software, and methodologies. These new microscopes provide researchers with powerful tools to explore the nanoworld with unprecedented detail and enable breakthroughs in various scientific disciplines.

Publicado en HRTEM, microscopy, nanocharacterization, nanotechnology, People, seminar | Comentarios desactivados en Director’s Team Seminar: A New Microscope in the Neighborhood by Ángel Landa

New publication: Iodine substituted hydroxyapatite nanoparticles and activation of derived ceramics for range verification in proton therapy

Publicada el 22 octubre, 2024 por agullo

Osteosarcoma is a radioresistant cancer and proton therapy a promising radiation alternative to treat cancer with the advantage of high dose concentration in the tumor area. In this work, we propose the use of iodine substituted hydroxyapatite nanomaterials (IHAP) to use iodine (127I) as a proton radiation tracer giving access to range verification studies in mineralized tissues. For this purpose, the nanomaterials were synthesized at four iodine concentrations by hydrothermal synthesis. The material is characterized using different microstructural techniques to identify an optimal high iodine concentration and pure apatite phase nanomaterial. Finally, such pure IHAP powders were shaped and irradiated with proton beams of 6 and 10 MeV and their activation demonstrated through subsequent decay analysis. The materials could be integrated in phantom structures for the verification of doses and range of protons prior to animal testing and clinical proton therapy treatments of tumors located deep under combined soft and calcified tissue.

R. Magro, A. Muñoz-Noval, J. A. Briz Monago, J. R. Murias, A. Espinosa Rodríguez, L. M. Fraile, F. Agulló-Rueda, M. D. Ynsa, C. Tavares de Sousa, B. Cortés Llanos, G. M. García López, E. Nacher, V. García Tavora, N. Mont i Geli, A. Nerio, V. Valladolid Onecha, R. Pallás, A. Tarifeno-Saldivia, O. Tengblad, M. J. Manso Silvan and S. Viñals i Onsés, «Iodine substituted hydroxyapatite nanoparticles and activation of derived ceramics for range verification in proton therapy,» J. Mater. Chem. B , (2024).

Publicado en microscopy, nanocharacterization, nanoscience, nanotechnology, Publications, Raman spectroscopy | Etiquetado , , , , | Comentarios desactivados en New publication: Iodine substituted hydroxyapatite nanoparticles and activation of derived ceramics for range verification in proton therapy

New publication: Out-of-plane preferential growth of 2D molybdenum diselenide nanosheets on laser-induced periodic surface structures

Publicada el 19 junio, 2024 por agullo

In this study, we explore the morphology and orientation of molybdenum diselenide, a Van der Waals 2D material, through isothermal closed space vapor deposition on both pristine and laser-structured substrates. Laser structuring is conducted on dielectric (sapphire), semiconductor (silicon), and conductive (titanium nitride) substrates using ultrashort laser pulses, resulting in smooth topographic changes such as laser-induced periodic surface structures (LIPSS) or selective ablation. Scanning electron microscopy (SEM) reveals the pivotal role of surface structuring in the growth of out-of-plane MoSe2 nanosheets. This effect is particularly pronounced on crystalline substrates like sapphire and silicon, exhibiting in-plane growth on pristine substrates. Additionally, Raman spectroscopy not only confirms the vertical orientation of flakes on structured substrates but also highlights the presence of active edge sites by demonstrating an increased abundance of deposited material. Overall, our findings emphasize the controllability of directing the growth of MoSe2 flakes through appropriate pre-treatment of the substrate, with potential applications in various fields, including Surface-Enhanced Raman Scattering (SERS). Furthermore, the scalability, reproducibility, and applicability to any substrate make ultrashort laser structuration a highly promising general strategy for orienting 2D materials.

A. Fernández García, R. Ariza, J. Solis, F. Agulló-Rueda, M. Manso Silvan, M. Garcia-Lechuga, «Out-of-plane growth of 2D molybdenum diselenide nanosheets on ultrafast laser-structured substrates,» Appl. Surf. Sci. 160567 (2024).

Publicado en microscopy, MoSe2, nanocharacterization, nanoscience, nanotechnology, Raman spectroscopy, semiconductor | Etiquetado , , , , , | Comentarios desactivados en New publication: Out-of-plane preferential growth of 2D molybdenum diselenide nanosheets on laser-induced periodic surface structures

Femtosecond laser thinning for resistivity control of tungsten ditelluride thin-films synthesized from sol-gel deposited tungsten oxide

Publicada el 30 noviembre, 2023 por agullo

In this work we present a route for fabricating WTe2 thin-films together with femtosecond laser post processing, enabling to finely control the conductivity. First, we produce amorphous films of WO3 on Si by spin-coating a sol-gel precursor followed by a consolidating annealing and a reduction process in partial H2 atmosphere, leading to porous metallic tungsten cluster layers. To achieve WTe2, the films were exposed to the chalcogen vapours by isothermal closed space vapor transport. The formation of a tungsten ditelluride film composed of piled crystals could be confirmed and a gradient of surface rich Te identified through hard X-ray photoelectron spectroscopy. Finally, it is demonstrated that resistivity can be changed from 0.2 mΩ.m to 1 mΩ.m, while keeping the material characteristics. An anisotropic conductivity can be induced by direct selective thinning with fs laser writing (350 fs pulse duration, 515 nm laser wavelength) of 1D stripes. The obtained results, demonstrate that laser processing is a promising thin-film post-processing technique that can be applied to 2D transition metal dichalcogenide thin films.

A. Fernández García, M. Garcia-Lechuga, F. Agulló-Rueda, J. Rubio Zuazo, and M. Manso Silvan, «Femtosecond laser thinning for resistivity control of tungsten ditelluride thin-films synthesized from sol-gel deposited tungsten oxide,» Surf. Interfaces 44, 103668 (2024).

Publicado en laser irradiation, microscopy, nanocharacterization, nanoscience, nanotechnology, Publications, Raman spectroscopy, semiconductor | Etiquetado | Comentarios desactivados en Femtosecond laser thinning for resistivity control of tungsten ditelluride thin-films synthesized from sol-gel deposited tungsten oxide

ICMM Days

Publicada el 9 octubre, 2023 por agullo

The Materials Science Institute of Madrid organized an internal meeting in Buitrago del Lozoya for a bbrief presentation of the different research groups and services. Here is the presentation from our group of Nanocharacterization of Materials (Nanocarma)

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Publicado en Gallery, HRTEM, ion irradiation, laser irradiation, microscopy, nanocharacterization, nanoscience, nanotechnology, People, Publications, Raman spectroscopy, Sin categoría, transition metal oxides | Etiquetado , , , , , , , , , | Comentarios desactivados en ICMM Days

Antibacterial Films of Silver Nanoparticles Embedded into Carboxymethylcellulose/Chitosan Multilayers on Nanoporous Silicon: A Layer-by-Layer Assembly Approach Comparing Dip and Spin Coating

Publicada el 31 agosto, 2023 por agullo

The design and engineering of antibacterial materials are key for preventing bacterial adherence and proliferation in biomedical and household instruments. Silver nanoparticles (AgNPs) and chitosan (CHI) are broad-spectrum antibacterial materials with different properties whose combined application is currently under optimization. This study proposes the formation of antibacterial films with AgNPs embedded in carboxymethylcellulose/chitosan multilayers by the layer-by-layer (LbL) method. The films were deposited onto nanoporous silicon (nPSi), an ideal platform for bioengineering applications due to its biocompatibility, biodegradability, and bioresorbability. We focused on two alternative multilayer deposition processes: cyclic dip coating (CDC) and cyclic spin coating (CSC). The physicochemical properties of the films were the subject of microscopic, microstructural, and surface–interface analyses. The antibacterial activity of each film was investigated against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria strains as model microorganisms. According to the findings, the CDC technique produced multilayer films with higher antibacterial activity for both bacteria compared to the CSC method. Bacteria adhesion inhibition was observed from only three cycles. The developed AgNPs–multilayer composite film offers advantageous antibacterial properties for biomedical applications.

N. Naveas, R. Pulido, V. Torres-Costa, F. Agulló-Rueda, M. Santibanez, F. Malano, G. Recio-Sánchez, K. Garrido-Miranda, M. Manso-Silván, J. Hernandez-Montelongo, «Antibacterial Films of Silver Nanoparticles Embedded into Carboxymethylcellulose/Chitosan Multilayers on Nanoporous Silicon: a Layer-by-Layer Assembly Approach Comparing Dip and Spin Coating,» Int. J. Mol. Sci. 24, 10595 (2023)

Publicado en Publications, Raman spectroscopy, silicon | Comentarios desactivados en Antibacterial Films of Silver Nanoparticles Embedded into Carboxymethylcellulose/Chitosan Multilayers on Nanoporous Silicon: A Layer-by-Layer Assembly Approach Comparing Dip and Spin Coating