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

Insights into the Synthesis Parameters Effects on the Structural, Morphological, and Magnetic Properties of Copper Oxide Nanoparticles

Publicada el 31 agosto, 2023 por agullo

The present study aims at the integration of the “oxalic conversion” route into “green chemistry” for the synthesis of copper oxide nanoparticles (CuO-NPs) with controllable structural, morphological, and magnetic properties. Two oxalate-containing precursors (H2C2O4.2H2O and (NH4)2C2O4.H2O) and different volume ratios of a mixed water/glycerol solvent were tested. First, the copper oxalates were synthesized and then subjected to thermal decomposition in air at 400 °C to produce the CuO powders. The purity of the samples was confirmed by X-ray powder diffraction (XRPD), and the crystallite sizes were calculated using the Scherrer method. The transmission electron microscopy (TEM) images revealed oval-shaped CuO-NPs, and the scanning electron microscopy (SEM) showed that morphological features of copper oxalate precursors and their corresponding oxides were affected by the glycerol (V/V) ratio as well as the type of C2O42- starting material. The magnetic properties of CuO-NPs were determined by measuring the temperature-dependent magnetization and the hysteresis curves at 5 and 300 K. The obtained results indicate the simultaneous coexistence of dominant antiferromagnetic and weak ferromagnetic behavior.

F. Mbarek, I. Chérif, A. Chérif, J. M. Alonso, I. Morales, P. de la Presa, S. Ammar, «Insights into the Synthesis Parameters Effects on the Structural, Morphological, and Magnetic Properties of Copper Oxide Nanoparticles,» Materials 16, 3426 (2023)

Publicado en HRTEM, Publications | Comentarios desactivados en Insights into the Synthesis Parameters Effects on the Structural, Morphological, and Magnetic Properties of Copper Oxide Nanoparticles

Transition from AFM Spin Canting to Spin Glass–AFM Exchange as Particle Size Decreases in LaFeO3

Publicada el 17 mayo, 2023 por agullo

In this work, we have studied structural and magnetic properties of LaFeO3 as a function of the particle size d, from bulk (d >> 1 μm) to nanoscale (d ≈ 30 nm). A large number of twins were observed for large particles that disappear for small particle sizes. This could be related to the softening of the FeO6 distortion as particle size decreases. It was observed that the bulk sample showed spin canting that disappeared for d ~ 125 nm and can be associated with the smoothening of the orthorhombic distortion. On the other hand, for d < 60 nm, the surface/volume ratio became high and, despite the high crystallinity of the nanoparticle, a notable exchange effect bias appeared, originated by two magnetic interactions: spin glass and antiferromagnetism. This exchange bias interaction was originated by the formation of a “magnetic core–shell”: the broken bonds at the surface atoms give place to a spin glass behavior, whereas the inner atoms maintain the anti-ferromagnetic G-type order. The LaFeO3 bulk material was synthesized by the ceramic method, whereas the LaFeO3 nanoparticles were synthesized by the sol-gel method; the particle size was varied by annealing the samples at different temperatures. The physical properties of the materials have been investigated by XRD, HRTEM, TGA, and AC and DC magnetometry.

En este trabajo hemos estudiado las propiedades estructurales y magnéticas de LaFeO3 en función del tamaño de partícula d, desde un tamaño de partícula grande (d >> 1 μm) hasta nanoescala (d ≈ 30 nm). Se observó un gran número de maclas para partículas grandes que desaparecen para partículas pequeñas. Esto podría estar relacionado con el ablandamiento de la distorsión de los octaedros FeO6 a medida que disminuye el tamaño de las partículas. Se observó que la muestra másica mostró un “canting” de espín que desapareció para d ~ 125 nm y puede estar asociada con el suavizado de la distorsión ortorrómbica. Por otro lado, para d < 60 nm, la relación superficie/volumen se hizo elevada y, a pesar de la alta cristalinidad de la nanopartícula, apareció un notable “bias” por efecto de intercambio, originado por dos interacciones magnéticas: “spin glass” y antiferromagnetismo. Esta interacción de intercambio de “bias” se originó por la formación de un «core-shell” magnético: los enlaces rotos en los átomos de la superficie dan lugar a un comportamiento de vidrio de espín, mientras que los átomos internos mantienen el orden antiferromagnético de tipo G. El material másico de LaFeO3 se sintetizó mediante el método cerámico, mientras que las nanopartículas de LaFeO3 se sintetizaron mediante el método sol-gel; el tamaño de partícula se varió recociendo las muestras a diferentes temperaturas. Las propiedades físicas de los materiales se han investigado mediante XRD, HRTEM, TGA y magnetometría AC y DC.

D. Alshalawi, J. M. Alonso, A. R. Landa-Cánovas, and P. de la Presa, “Transition from AFM Spin Canting to Spin Glass–AFM Exchange as Particle Size Decreases in LaFeO3,” Nanomaterials 13, 1657 (2023)

Publicado en HRTEM, Publications, transition metal oxides | Comentarios desactivados en Transition from AFM Spin Canting to Spin Glass–AFM Exchange as Particle Size Decreases in LaFeO3

TEM study of ∼PbCr2S4 columnar misfit phases

Publicada el 12 enero, 2023 por agullo


The disordered structure of the columnar misfit ​∼ ​PbCr2S4 phase (∼ character indicates that it is close to the stoichiometric composition but slightly away) has been revealed by means of transmission electron microscopy (TEM) varied techniques such as selected area electron diffraction (SAED), high-resolution TEM (HRTEM), dark-field TEM and high-angle annular dark field (HAADF) in scanning-transmision (STEM) mode. The structure consists of a hexagonal framework (Cr21S36), with unit cell parameters a0 ​= ​b0 ​= ​21.407 (1) Å and c0 ​  ​3.476 (1), and with hexagonal (Pb6Cr2S6) and trigonal columns (Pb3S) with the same a and b parameters and different c: c3 ​= ​3.98 Å; c6 ​= ​5.62 ​Å, measured by electron diffraction. While the framework exhibit no crystalline disorder, the arrangement of the two types of columns is disordered. This disorder is shown by electron diffraction as diffuse scattering planes which are perpendicular to the framework c axis and parallel to the a∗b∗ plane. While the disorder between hexagonal columns is due to the lack of correlation between different columns, we observe in the trigonal columns also the presence of intra-columnar atomic disorder. X-ray wavelength dispersive spectroscopy (XWDS) analyses produce Pb0.81(1)Cr2S3.97(6) composition. TEM imaging techniques suggest lack of correlation between trigonal columns as the cause for the observed disorder as well as inside-the-column structural disorder in Pb3S trigonal columns.

A. Gómez-Herrero, A. R. Landa-Cánovas, and L. C. Otero-Díaz, “TEM study of ∼PbCr2S4 columnar misfit phases,” J. Solid State Chem. 319, 123826 (2023)

Publicado en HRTEM, microscopy, nanocharacterization | Comentarios desactivados en TEM study of ∼PbCr2S4 columnar misfit phases

Coexistence of Two Spin Frustration Pathways in the Quantum Spin Liquid Ca10Cr7O28

Publicada el 21 octubre, 2022 por agullo

Kagome antiferromagnetic lattices are of high interest because the geometric frustration is expected to give rise to highly degenerated ground states that may host exotic properties such as quantum spin liquid (QSL). Ca10Cr7O28 has been reported to display all the features expected for a QSL. At present, most of the literature reports on samples synthesized with starting materials ratio CaO/Cr2O3 3:1, which leads to a material with small amounts of CaCrO4 and CaO as secondary phases; this impurity excess affects not only the magnetic properties but also the structural ones. In this work, samples with starting material ratios CaO/Cr2O3 3:1, 2.9:1, 2.85:1, and 2.8:1 have been synthesized and studied by X-ray diffraction with Rietveld refinements, selected area electron diffraction
measurements, high-resolution transmission electron microscopy (HRTEM), low-temperature magnetometry, and magnetic calorimetry. This result shows that a highly pure Ca10Cr7O28 phase is obtained for a CaO/Cr2O3 ratio of 2.85:1 instead of the 3:1 usually reported; the incorrect stoichiometric ratio leads to a larger distortion of the corner-sharing triangular arrangement of magnetic ions Cr+5 with S = 1/2 in the Kagome lattice. In addition, our study reveals that there exists another frustration pathway which is an asymmetric zigzag spin ladder along the directions [211], [12−1], and [1−1−1], in which the Cr−Cr distances are shorter than in the Kagome layers.


D. R. Alshalawi, J. M. Alonso, A. R. Landa-Cánovas, and P. de la Presa, «Coexistence of Two Spin Frustration Pathways in the Quantum Spin Liquid Ca10Cr7O28,» Inorg. Chem. 61, 16228 (2022).

Publicado en HRTEM, microscopy, nanocharacterization, nanoscience, Publications, transition metal oxides | Comentarios desactivados en Coexistence of Two Spin Frustration Pathways in the Quantum Spin Liquid Ca10Cr7O28

Spatially resolved MoOx phases by laser localized oxidation of MoO2

Publicada el 20 abril, 2021 por agullo


MoO2 thin films were subjected to a laser localized oxidation process that allowed to obtain different well defined MoOx phases. In particular, spatially resolved MoO2, α-MoO3, β-MoO3, amorphous a-MoO3, and Mo4O11 regions were obtained as a function of the laser power and the distance to the laser focus. The origin of this spatial phase separation was investigated through a careful and exhaustive Raman mapping study covering several micrometres away from the laser focus and taking into account the thermochemical properties of the species involved. It was found that a sublimation/deposition process, driven by the different vapour pressures of the species, was responsible for the phase separation. At higher laser power, a solid state reaction was observed to contribute as well. In the laser annealed tracks, distant lateral sidebands of oxide deposition were observed with composition that depended on the laser power and the distance to the centre of the track. Electrical measurements between irradiated and non-irradiated regions showed a strong rectifying behaviour, revealing a transformation from metal-like to semiconducting Mo oxide phases, which may open the way to the development of laser written all-oxide electronic circuits.

O. de Melo, F. Agulló-Rueda and V. Torres-Costa, “Spatially resolved MoOx phases by laser localized oxidation of MoO2: A possible route for all-molybdenum-oxide devices,” J. Mater. Chem. C 9, 6579–6588 (2021).

Publicado en laser irradiation, microscopy, nanocharacterization, Raman spectroscopy, semiconductor, Sin categoría, transition metal oxides | Etiquetado , , , , , , | Comentarios desactivados en Spatially resolved MoOx phases by laser localized oxidation of MoO2