Papers
1.
Rached, A.; Wederni, M. A.; Alaya, S.; Martín-Palma, R. J.; Khirouni, K.
Effects of the substitution in the two sites on barium titanate properties Journal Article
In: Inorganic Chemistry Communications, vol. 172, 2025.
@article{rached_effects_2025,
title = {Effects of the substitution in the two sites on barium titanate properties},
author = {A. Rached and M. A. Wederni and S. Alaya and R. J. Martín-Palma and K. Khirouni},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85211161739&doi=10.1016%2fj.inoche.2024.113675&partnerID=40&md5=d4ccd1056fece039e03f7b658bf18d89},
doi = {10.1016/j.inoche.2024.113675},
year = {2025},
date = {2025-01-01},
journal = {Inorganic Chemistry Communications},
volume = {172},
abstract = {Barium titanate compound has been studied given their many interesting physico-chemical properties, including their dielectric and ferroelectric behavior. Besides, the introduction of different elements in the barium titanate matrix increases the number of applications in which these compounds can be used. Within this context, in the present work we investigated the effect of doping barium titanate with alkali ions (Ca) and rare earth ions (Er) in Ba sites and by tin ions in Ti sites. The synthesized compound, termed BETS-Ca, was prepared via a solid–solid reaction technique. X-ray diffraction measurements indicated that the material has a tetragonal symmetry structure. Scanning electron microscopy analysis allowed to identify a dense microstructure with the existence of both grain and grain boundaries. Moreover, optical absorbance and infrared spectra indicated the incorporation of doping elements such as erbium and tin. Additionally, the electric and dielectric properties of the compounds were investigated. AC conductivity analysis suggested that conduction is governed by correlated barriers hopping and non overlapping small polaron tunneling processes. Nyquist plot showed the contribution of both grain and grain boundaries to the conduction. Finally, a ferroelectric-paraelectric transition was found around a specific temperature (TC = 360 K). According to the Curie-Weiss law, this transition has a diffusive character. © 2024 Elsevier B.V.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Barium titanate compound has been studied given their many interesting physico-chemical properties, including their dielectric and ferroelectric behavior. Besides, the introduction of different elements in the barium titanate matrix increases the number of applications in which these compounds can be used. Within this context, in the present work we investigated the effect of doping barium titanate with alkali ions (Ca) and rare earth ions (Er) in Ba sites and by tin ions in Ti sites. The synthesized compound, termed BETS-Ca, was prepared via a solid–solid reaction technique. X-ray diffraction measurements indicated that the material has a tetragonal symmetry structure. Scanning electron microscopy analysis allowed to identify a dense microstructure with the existence of both grain and grain boundaries. Moreover, optical absorbance and infrared spectra indicated the incorporation of doping elements such as erbium and tin. Additionally, the electric and dielectric properties of the compounds were investigated. AC conductivity analysis suggested that conduction is governed by correlated barriers hopping and non overlapping small polaron tunneling processes. Nyquist plot showed the contribution of both grain and grain boundaries to the conduction. Finally, a ferroelectric-paraelectric transition was found around a specific temperature (TC = 360 K). According to the Curie-Weiss law, this transition has a diffusive character. © 2024 Elsevier B.V.
2.
Saddik, K. Ben; Hernández, M. J.; Pampillón, M. A.; Cervera, M.; García, B. J.
On the absorption coefficient of GaP1-xNx layers and its potential application for silicon photovoltaics Journal Article
In: Materials Science in Semiconductor Processing, vol. 185, 2025.
@article{ben_saddik_absorption_2025,
title = {On the absorption coefficient of GaP1-xNx layers and its potential application for silicon photovoltaics},
author = {K. Ben Saddik and M. J. Hernández and M. A. Pampillón and M. Cervera and B. J. García},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85206315773&doi=10.1016%2fj.mssp.2024.109011&partnerID=40&md5=3aa2b52744ca9b9eb92377cf4971b44f},
doi = {10.1016/j.mssp.2024.109011},
year = {2025},
date = {2025-01-01},
journal = {Materials Science in Semiconductor Processing},
volume = {185},
abstract = {The absorption coefficient and the energy gap of GaP1-xNx layers has been obtained by spectroscopic ellipsometry for samples grown on Si(001) substrates by chemical beam epitaxy with N mole fractions in the range 0 ≤ x ≤ 0.081. The resulting absorption spectra exhibit a direct band-like behavior near the absorption edge. The absorption coefficient values increase with the N content, reaching values in the range α ∼ 1-2x104 cm−1 in the vicinity of the absorption edge below the original GaP direct bandgap, which are comparable to those obtained for high efficiency solar cell materials. Furthermore, dependence of the absorption coefficient with increasing N content points to a strong GaP Γ-like character of the conduction-band wave function of GaP1-xNx alloys near the Brillouin zone center at k = 0, as predicted by the band anticrossing model. Bandgap energy values obtained by spectroscopic ellipsometry are compared with previous values obtained by photoluminescence measurements on the same samples, observing a shift of about 50–100 meV. Finally, the value of the band anticrossing parameter coupling the N level and the host GaP conduction band has been obtained from the dependence of both, the bandgap and the absorption coefficient, with the N content (2.1 and 3.3 eV respectively). © 2024},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The absorption coefficient and the energy gap of GaP1-xNx layers has been obtained by spectroscopic ellipsometry for samples grown on Si(001) substrates by chemical beam epitaxy with N mole fractions in the range 0 ≤ x ≤ 0.081. The resulting absorption spectra exhibit a direct band-like behavior near the absorption edge. The absorption coefficient values increase with the N content, reaching values in the range α ∼ 1-2x104 cm−1 in the vicinity of the absorption edge below the original GaP direct bandgap, which are comparable to those obtained for high efficiency solar cell materials. Furthermore, dependence of the absorption coefficient with increasing N content points to a strong GaP Γ-like character of the conduction-band wave function of GaP1-xNx alloys near the Brillouin zone center at k = 0, as predicted by the band anticrossing model. Bandgap energy values obtained by spectroscopic ellipsometry are compared with previous values obtained by photoluminescence measurements on the same samples, observing a shift of about 50–100 meV. Finally, the value of the band anticrossing parameter coupling the N level and the host GaP conduction band has been obtained from the dependence of both, the bandgap and the absorption coefficient, with the N content (2.1 and 3.3 eV respectively). © 2024
3.
Caukwell, J.; Assenza, S.; Hassan, K. A.; Neilan, B. A.; Clulow, A. J.; Manni, L. Salvati; Fong, W. -K.
Lipidic drug delivery systems are responsive to the human microbiome Journal Article
In: Journal of Colloid and Interface Science, vol. 677, pp. 293–302, 2025.
@article{caukwell_lipidic_2025,
title = {Lipidic drug delivery systems are responsive to the human microbiome},
author = {J. Caukwell and S. Assenza and K. A. Hassan and B. A. Neilan and A. J. Clulow and L. Salvati Manni and W. -K. Fong},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85201165361&doi=10.1016%2fj.jcis.2024.07.216&partnerID=40&md5=a0a246b5664c78e364c50092b07da390},
doi = {10.1016/j.jcis.2024.07.216},
year = {2025},
date = {2025-01-01},
journal = {Journal of Colloid and Interface Science},
volume = {677},
pages = {293–302},
abstract = {In vitro and in vivo tests for therapeutic agents are typically conducted in sterile environments, but many target areas for drug delivery are home to thousands of microbial species. Here, we examine the behaviour of lipidic nanomaterials after exposure to representative strains of four bacterial species found in the gastrointestinal tract and skin. Small angle X-ray scattering measurements show that the nanostructure of monoolein cubic and inverse hexagonal phases are transformed, respectively, into inverse hexagonal and inverse micellar cubic phases upon exposure to a strain of live Staphylococcus aureus often present on skin and mucosa. Further investigation demonstrates that enzymatic hydrolysis and cell membrane lipid transfer are both likely responsible for this effect. The structural responses to S. aureus are rapid and significantly reduce the rate of drug release from monoolein-based nanomaterials. These findings are the first to demonstrate how a key species in the live human microbiome can trigger changes in the structure and drug release properties of lipidic nanomaterials. The effect appears to be strain specific, varies from patient to patient and body region to body region, and is anticipated to affect the bioapplication of monoglyceride-based formulations. © 2024 The Author(s)},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In vitro and in vivo tests for therapeutic agents are typically conducted in sterile environments, but many target areas for drug delivery are home to thousands of microbial species. Here, we examine the behaviour of lipidic nanomaterials after exposure to representative strains of four bacterial species found in the gastrointestinal tract and skin. Small angle X-ray scattering measurements show that the nanostructure of monoolein cubic and inverse hexagonal phases are transformed, respectively, into inverse hexagonal and inverse micellar cubic phases upon exposure to a strain of live Staphylococcus aureus often present on skin and mucosa. Further investigation demonstrates that enzymatic hydrolysis and cell membrane lipid transfer are both likely responsible for this effect. The structural responses to S. aureus are rapid and significantly reduce the rate of drug release from monoolein-based nanomaterials. These findings are the first to demonstrate how a key species in the live human microbiome can trigger changes in the structure and drug release properties of lipidic nanomaterials. The effect appears to be strain specific, varies from patient to patient and body region to body region, and is anticipated to affect the bioapplication of monoglyceride-based formulations. © 2024 The Author(s)
4.
Toural, J. L. Sánchez; García-Pérez, J.; Bernardo-Gavito, R.; Granados, D.; Andrino-Gómez, A.; García, G.; Pau, J. L.; Ramos, M. A.; Gordillo, N.
Diamond-defect engineering of NV− centers using ion beam irradiation Journal Article
In: Diamond and Related Materials, vol. 151, 2025.
@article{sanchez_toural_diamond-defect_2025,
title = {Diamond-defect engineering of NV− centers using ion beam irradiation},
author = {J. L. Sánchez Toural and J. García-Pérez and R. Bernardo-Gavito and D. Granados and A. Andrino-Gómez and G. García and J. L. Pau and M. A. Ramos and N. Gordillo},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85210653060&doi=10.1016%2fj.diamond.2024.111838&partnerID=40&md5=f60b4304bf40959bc9d51444326d396f},
doi = {10.1016/j.diamond.2024.111838},
year = {2025},
date = {2025-01-01},
journal = {Diamond and Related Materials},
volume = {151},
abstract = {The interplay between ion beam modification techniques in the MeV range and the controlled generation of negatively charged nitrogen-vacancy (NV−) centers in nitrogen-doped synthetic diamond crystals is explored. An experimental approach employing both light (H+) and heavy (Br+6) ions was followed to assess their respective impacts on the creation of NV− centers, using different ion energies or fluences to generate varying amounts of vacancies. Photoluminescence spectroscopy was applied to characterize NV− and neutral NV0 centers. Initially, no NV centers were detected post-irradiation, despite the presence of substitutional nitrogen and vacancies. However, after annealing at 800 °C (and in some cases at 900 °C), most samples exhibited a high density of NV0 and especially NV− centers. This demonstrates that thermal treatment is essential for vacancy‑nitrogen recombination and NV− formation, often through electron capture from nearby nitrogen atoms. Notably, we achieved high NV− densities without graphitization, which is essential for preserving the material's properties for quantum applications. This study underscores and quantifies the effectiveness of MeV-range ions in controlling vacancy distributions and highlights their potential for optimizing NV− center formation to enhance the sensitivity of diamond-based quantum magnetic sensors. © 2024 The Authors},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The interplay between ion beam modification techniques in the MeV range and the controlled generation of negatively charged nitrogen-vacancy (NV−) centers in nitrogen-doped synthetic diamond crystals is explored. An experimental approach employing both light (H+) and heavy (Br+6) ions was followed to assess their respective impacts on the creation of NV− centers, using different ion energies or fluences to generate varying amounts of vacancies. Photoluminescence spectroscopy was applied to characterize NV− and neutral NV0 centers. Initially, no NV centers were detected post-irradiation, despite the presence of substitutional nitrogen and vacancies. However, after annealing at 800 °C (and in some cases at 900 °C), most samples exhibited a high density of NV0 and especially NV− centers. This demonstrates that thermal treatment is essential for vacancy‑nitrogen recombination and NV− formation, often through electron capture from nearby nitrogen atoms. Notably, we achieved high NV− densities without graphitization, which is essential for preserving the material's properties for quantum applications. This study underscores and quantifies the effectiveness of MeV-range ions in controlling vacancy distributions and highlights their potential for optimizing NV− center formation to enhance the sensitivity of diamond-based quantum magnetic sensors. © 2024 The Authors
5.
Tabares, G.; Magro, R.; Vázquez, L.; Fernandez, A.; Gordillo, N.
MoSe2xTe2–2x alloy for hydrogen gas detection Journal Article
In: Sensors and Actuators A: Physical, vol. 382, 2025.
@article{tabares_mose2xte22x_2025,
title = {MoSe2xTe2–2x alloy for hydrogen gas detection},
author = {G. Tabares and R. Magro and L. Vázquez and A. Fernandez and N. Gordillo},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85211967844&doi=10.1016%2fj.sna.2024.116126&partnerID=40&md5=23f06089f1c8f563c7395798c9007018},
doi = {10.1016/j.sna.2024.116126},
year = {2025},
date = {2025-01-01},
journal = {Sensors and Actuators A: Physical},
volume = {382},
abstract = {This study presents one of the first detailed investigation into the out-of-plane growth of two-dimensional MoSe2xTe2–2x for three distinct Se:Te compositions, yielding the samples MoSe0.46Te1.55, MoSe0.55Te1.45, and MoSe0.64Te1.35. Scanning electron microscopy reveals the morphological evolution, showcasing nanoflakes predominantly grown in a random out-of-plane orientation. Raman spectroscopy confirms the crystal structure of MoSe2xTe2–2x samples, with no detectable traces of MoO3 or MoO2 precursors. Distinctive peaks validate the presence of MoSe2xTe2–2x, while spectral shifts suggest at compositional variations. Conductive-Atomic Force Microscopy (C-AFM) was used to quantify current flow between a diamond-doped AFM tip and the sample. Additionally, the resistances of compositions MoSe0.46Te1.55, MoSe0.55Te1.45, and MoSe0.64Te1.35 were characterized, yielding median values of 108.0 Ω, 25.4 kΩ, and 240.0 kΩ, respectively, indicating diverse electrical properties associated with Se content. Notably, the sample with the highest Se content exhibits increased resistivity as anticipated, consistent with XRD spectra results. Finally, gas-sensing performance is evaluated by assessing electrical resistance variations before and after exposure to H2 gas at various temperatures, revealing significant changes indicative of enhanced charge flow upon H2 exposure. © 2024 The Authors},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
This study presents one of the first detailed investigation into the out-of-plane growth of two-dimensional MoSe2xTe2–2x for three distinct Se:Te compositions, yielding the samples MoSe0.46Te1.55, MoSe0.55Te1.45, and MoSe0.64Te1.35. Scanning electron microscopy reveals the morphological evolution, showcasing nanoflakes predominantly grown in a random out-of-plane orientation. Raman spectroscopy confirms the crystal structure of MoSe2xTe2–2x samples, with no detectable traces of MoO3 or MoO2 precursors. Distinctive peaks validate the presence of MoSe2xTe2–2x, while spectral shifts suggest at compositional variations. Conductive-Atomic Force Microscopy (C-AFM) was used to quantify current flow between a diamond-doped AFM tip and the sample. Additionally, the resistances of compositions MoSe0.46Te1.55, MoSe0.55Te1.45, and MoSe0.64Te1.35 were characterized, yielding median values of 108.0 Ω, 25.4 kΩ, and 240.0 kΩ, respectively, indicating diverse electrical properties associated with Se content. Notably, the sample with the highest Se content exhibits increased resistivity as anticipated, consistent with XRD spectra results. Finally, gas-sensing performance is evaluated by assessing electrical resistance variations before and after exposure to H2 gas at various temperatures, revealing significant changes indicative of enhanced charge flow upon H2 exposure. © 2024 The Authors
6.
Rodríguez-Tapiador, M. I.; Mánuel, J. M.; Blanco, E.; Márquez, E.; Gordillo, N.; Sainz, R.; Merino, J.; Fernández, S.
In: Materials Science in Semiconductor Processing, vol. 188, 2025.
@article{rodriguez-tapiador_effect_2025,
title = {Effect of N2 concentration on structural, morphological, and optoelectronic properties of Cu3N films fabricated by RF magnetron sputtering for photodetection applications},
author = {M. I. Rodríguez-Tapiador and J. M. Mánuel and E. Blanco and E. Márquez and N. Gordillo and R. Sainz and J. Merino and S. Fernández},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85211193003&doi=10.1016%2fj.mssp.2024.109176&partnerID=40&md5=29230c71895b36332c9e6b9fca52f871},
doi = {10.1016/j.mssp.2024.109176},
year = {2025},
date = {2025-01-01},
journal = {Materials Science in Semiconductor Processing},
volume = {188},
abstract = {Copper nitride (Cu3N) is a promising eco-friendly material for photodetection and photovoltaic absorption. This study focuses on fabricating high-quality Cu3N thin films via reactive radio-frequency magnetron sputtering, using pure N2 and N2/Ar mixture environments, respectively. We investigate how variations in the substrate temperature and the working gas pressure affect absorption capabilities. Phase structure analysis confirms an anti-ReO3 structure with a preferred (100) orientation, and lattice parameters between 0.3810 and 0.3832 nm, with electrical resistivity around 104 Ω cm, indicating a semiconductor character. The films exhibit improved crystalline quality when deposited in pure N2 at 100 °C. Rutherford Backscattering Spectrometry reveals non-stoichiometric films with Cu/N ratios close to 3. The work function showed by the films deposited in N2/Ar is approximately 4.45 eV, while for those deposited in pure N2, the values range from 4.30 to 4.62 eV. Optical properties show a high absorbance and a variable refractive index depending on the deposition conditions. Lastly, the Cu3N films deposited at 100 °C in pure N2 exhibit enhanced photocurrent and photosensitivity of 3.78 × 10−8 A and 9644.9 %, respectively, at 10 V and using AM1.5G as light source. This result underscores the importance of plasma composition as a key factor for obtaining a material with great potential to be applied in such applications. © 2024},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Copper nitride (Cu3N) is a promising eco-friendly material for photodetection and photovoltaic absorption. This study focuses on fabricating high-quality Cu3N thin films via reactive radio-frequency magnetron sputtering, using pure N2 and N2/Ar mixture environments, respectively. We investigate how variations in the substrate temperature and the working gas pressure affect absorption capabilities. Phase structure analysis confirms an anti-ReO3 structure with a preferred (100) orientation, and lattice parameters between 0.3810 and 0.3832 nm, with electrical resistivity around 104 Ω cm, indicating a semiconductor character. The films exhibit improved crystalline quality when deposited in pure N2 at 100 °C. Rutherford Backscattering Spectrometry reveals non-stoichiometric films with Cu/N ratios close to 3. The work function showed by the films deposited in N2/Ar is approximately 4.45 eV, while for those deposited in pure N2, the values range from 4.30 to 4.62 eV. Optical properties show a high absorbance and a variable refractive index depending on the deposition conditions. Lastly, the Cu3N films deposited at 100 °C in pure N2 exhibit enhanced photocurrent and photosensitivity of 3.78 × 10−8 A and 9644.9 %, respectively, at 10 V and using AM1.5G as light source. This result underscores the importance of plasma composition as a key factor for obtaining a material with great potential to be applied in such applications. © 2024
7.
Sanz-García, J. A.; Lifante-Pedrola, G.; Santiuste, J. E. M.; Cantelar, E.
Dual luminescent nano-thermometry based on the selective excitation of optical centers in CaF2:Er3+ nanoparticles Journal Article
In: Journal of Alloys and Compounds, vol. 1010, 2025.
@article{sanz-garcia_dual_2025,
title = {Dual luminescent nano-thermometry based on the selective excitation of optical centers in CaF2:Er3+ nanoparticles},
author = {J. A. Sanz-García and G. Lifante-Pedrola and J. E. M. Santiuste and E. Cantelar},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85208764495&doi=10.1016%2fj.jallcom.2024.177529&partnerID=40&md5=e54bcd3b17dbdcf9efc52a9391093b1e},
doi = {10.1016/j.jallcom.2024.177529},
year = {2025},
date = {2025-01-01},
journal = {Journal of Alloys and Compounds},
volume = {1010},
abstract = {We present a study about the feasibility of using the upconverted luminescence of CaF2:Er3+ nanoparticles (NPs), under near infrared excitation within the 4I15/2 → 4I11/2 absorption band, for thermal detection. In order to perform this study, it has been needed to investigate the upconversion processes as function of the Er3+ concentration and the excitation wavelength by using a tunable Ti:Sapphire laser. The results obtained indicate that, under this excitation scheme, the green (2H11/2:4S3/2) and red (4F9/2) emitting levels are populated through different multiphoton processes: Excited state absorption and energy transfer upconversion. Therefore, the ratio between the green and red emissions is also dependent on the Er3+ concentration and the excitation wavelength. Measurements based on site-selective emission/excitation, performed at room temperature, indicate that in these NPs there are at least two different optical centers whose emission bands can be isolated by an appropriate selection of the excitation wavelength. One these centers is compatible with the presence of isolated Er3+ ions, while the other one is tentatively related to the presence of clusters or aggregates. The upconverted luminescence of each optical center is analyzed as function of temperature by means of the ratiometric Fluorescence Intensity Ratio technique. The results indicate that both optical centers exhibit adequate thermal performances and relative sensitivities to be used in thermal sensing. © 2024 The Authors},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We present a study about the feasibility of using the upconverted luminescence of CaF2:Er3+ nanoparticles (NPs), under near infrared excitation within the 4I15/2 → 4I11/2 absorption band, for thermal detection. In order to perform this study, it has been needed to investigate the upconversion processes as function of the Er3+ concentration and the excitation wavelength by using a tunable Ti:Sapphire laser. The results obtained indicate that, under this excitation scheme, the green (2H11/2:4S3/2) and red (4F9/2) emitting levels are populated through different multiphoton processes: Excited state absorption and energy transfer upconversion. Therefore, the ratio between the green and red emissions is also dependent on the Er3+ concentration and the excitation wavelength. Measurements based on site-selective emission/excitation, performed at room temperature, indicate that in these NPs there are at least two different optical centers whose emission bands can be isolated by an appropriate selection of the excitation wavelength. One these centers is compatible with the presence of isolated Er3+ ions, while the other one is tentatively related to the presence of clusters or aggregates. The upconverted luminescence of each optical center is analyzed as function of temperature by means of the ratiometric Fluorescence Intensity Ratio technique. The results indicate that both optical centers exhibit adequate thermal performances and relative sensitivities to be used in thermal sensing. © 2024 The Authors
8.
Hernández-Gutiérrez, J.; Sebastián-Vicente, C.; García-Cabañes, A.; Carrascosa, M.
Light-assisted patterning of salt precipitation on photovoltaic LiNbO3 substrates Journal Article
In: European Physical Journal Plus, vol. 139, no. 3, 2024.
@article{hernandez-gutierrez_light-assisted_2024,
title = {Light-assisted patterning of salt precipitation on photovoltaic LiNbO3 substrates},
author = {J. Hernández-Gutiérrez and C. Sebastián-Vicente and A. García-Cabañes and M. Carrascosa},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85186539821&doi=10.1140%2fepjp%2fs13360-024-04994-7&partnerID=40&md5=bfccfe8ad480f1b00dd573df8e0e0f39},
doi = {10.1140/epjp/s13360-024-04994-7},
year = {2024},
date = {2024-01-01},
journal = {European Physical Journal Plus},
volume = {139},
number = {3},
abstract = {The control of salt crystallization on a surface has important implications in many technological and industrial applications. In this work, we propose and demonstrate an optoelectrical method to define and control the spatial distribution of salt crystallization on a lithium niobate photovoltaic substrate. It is based on the bulk photovoltaic effect that generates an electric field on the illuminated regions of the crystal. The salt only crystallizes on these illuminated regions of the substrate. Single salt spots or more complicated spatial patterns, defined by the light intensity spatial distribution, have been achieved. In particular, some results have been obtained using scanning/moving laser beams, i.e., “drawing” the saline patterns. The role of light exposure time and salt concentration in the aqueous solution has been studied. The method has been checked with several salts with successful results showing its general applicability. A discussion on the possible physical mechanisms behind the method and their implication for the operation of photovoltaic platforms in other applications is also included. © The Author(s) 2024.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The control of salt crystallization on a surface has important implications in many technological and industrial applications. In this work, we propose and demonstrate an optoelectrical method to define and control the spatial distribution of salt crystallization on a lithium niobate photovoltaic substrate. It is based on the bulk photovoltaic effect that generates an electric field on the illuminated regions of the crystal. The salt only crystallizes on these illuminated regions of the substrate. Single salt spots or more complicated spatial patterns, defined by the light intensity spatial distribution, have been achieved. In particular, some results have been obtained using scanning/moving laser beams, i.e., “drawing” the saline patterns. The role of light exposure time and salt concentration in the aqueous solution has been studied. The method has been checked with several salts with successful results showing its general applicability. A discussion on the possible physical mechanisms behind the method and their implication for the operation of photovoltaic platforms in other applications is also included. © The Author(s) 2024.
9.
Zamboni, R.; Sebastián-Vicente, C.; Denz, C.; Imbrock, J.
Light-Induced Virtual Electrodes for Microfluidic Droplet Electro-Coalescence Journal Article
In: Advanced Functional Materials, vol. 34, no. 13, 2024.
@article{zamboni_light-induced_2024,
title = {Light-Induced Virtual Electrodes for Microfluidic Droplet Electro-Coalescence},
author = {R. Zamboni and C. Sebastián-Vicente and C. Denz and J. Imbrock},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85179730946&doi=10.1002%2fadfm.202305286&partnerID=40&md5=aa726ac635cf5be1511a49febc60fe26},
doi = {10.1002/adfm.202305286},
year = {2024},
date = {2024-01-01},
journal = {Advanced Functional Materials},
volume = {34},
number = {13},
abstract = {Electro-coalescence is the fusion phenomenon between a pair or more microfluidic droplets that are immersed in an immiscible medium under an electric field. This technique is frequently used to merge confined droplets in surfactant-stabilized microfluidic emulsions using local electric fields. Despite the necessity of miniaturized electrodes, this method has proven highly successful in microfluidics and lab-on-a-chip applications. Miniaturized electrodes severely curtail the spatial and temporal flexibility of the electric potential, thus hindering real-time and flexible operation and leading to high production costs. The current study addresses this problem with reconfigurable electric field potential by light-driven functional virtual electrodes. These electrodes are light-induced on a non-centrosymmetric ferroelectric photovoltaic crystal placed below a microfluidic droplet channel. The photovoltaic effect in the crystal is responsible for the space charge distributions that act as virtual electrodes, whose evanescent field is screened by free charges into the two liquids inside the channel. A numerical model is developed to describe the evolution of the evanescent electric field causing electro-coalescence. Based on this prediction, two coalescence processes occur at two different timescales and with different numbers of droplets involved. Controlled exposure time modulation allows either rapid on-demand coalescence of droplet pairs or breakup of the entire emulsion. © 2023 The Authors. Advanced Functional Materials published by Wiley-VCH GmbH.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Electro-coalescence is the fusion phenomenon between a pair or more microfluidic droplets that are immersed in an immiscible medium under an electric field. This technique is frequently used to merge confined droplets in surfactant-stabilized microfluidic emulsions using local electric fields. Despite the necessity of miniaturized electrodes, this method has proven highly successful in microfluidics and lab-on-a-chip applications. Miniaturized electrodes severely curtail the spatial and temporal flexibility of the electric potential, thus hindering real-time and flexible operation and leading to high production costs. The current study addresses this problem with reconfigurable electric field potential by light-driven functional virtual electrodes. These electrodes are light-induced on a non-centrosymmetric ferroelectric photovoltaic crystal placed below a microfluidic droplet channel. The photovoltaic effect in the crystal is responsible for the space charge distributions that act as virtual electrodes, whose evanescent field is screened by free charges into the two liquids inside the channel. A numerical model is developed to describe the evolution of the evanescent electric field causing electro-coalescence. Based on this prediction, two coalescence processes occur at two different timescales and with different numbers of droplets involved. Controlled exposure time modulation allows either rapid on-demand coalescence of droplet pairs or breakup of the entire emulsion. © 2023 The Authors. Advanced Functional Materials published by Wiley-VCH GmbH.
10.
Sebastián-Vicente, C.; Zamboni, R.; García-Cabañes, A.; Carrascosa, M.
Photovoltaic Charge Lithography on Passive Dielectric Substrates Using Fe:LiNbO3 Stamps Journal Article
In: Advanced Electronic Materials, 2024.
@article{sebastian-vicente_photovoltaic_2024,
title = {Photovoltaic Charge Lithography on Passive Dielectric Substrates Using Fe:LiNbO3 Stamps},
author = {C. Sebastián-Vicente and R. Zamboni and A. García-Cabañes and M. Carrascosa},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85205676617&doi=10.1002%2faelm.202400327&partnerID=40&md5=76dac885bb076773f6a3e70e0be8c86b},
doi = {10.1002/aelm.202400327},
year = {2024},
date = {2024-01-01},
journal = {Advanced Electronic Materials},
abstract = {Photovoltaic Fe:LiNbO3 is an outstanding material platform able to photo-generate versatile charge patterns, useful for a broad variety of applications. However, in some cases, its photorefractive effect, light absorption, and active ferroelectric properties may interfere with the optimum operation of certain devices based on Fe:LiNbO3. Here, a novel optoelectronic method is proposed and demonstrated to transfer photovoltaic charge patterns from Fe:LiNbO3 to non-photovoltaic passive substrates, thus removing these possible limitations. The method, denominated as photovoltaic charge lithography (PVCL), resembles the operation of a stamp and does not require external high-voltage supplies or electron/ion beams. Upon contact between the active Fe:LiNbO3 stamp and a passive dielectric substrate, the light-induced charge pattern can be faithfully mirrored on the passive substrate. The imprinted pattern is probed and characterized by dielectrophoretic and electrophoretic particle trapping. The results reveal that the charge builds up on the passive substrate during contact, allowing charge tunability. Moreover, arbitrary charge distributions can be flexibly tailored, using scanning laser beams or spatially structured light. Overall, PVCL opens the possibility of printing complex 1D/2D charge patterns of controlled polarity on different passive dielectric materials, enhancing the technological potential of Fe:LiNbO3 photovoltaic platforms. © 2024 The Author(s). Advanced Electronic Materials published by Wiley-VCH GmbH.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Photovoltaic Fe:LiNbO3 is an outstanding material platform able to photo-generate versatile charge patterns, useful for a broad variety of applications. However, in some cases, its photorefractive effect, light absorption, and active ferroelectric properties may interfere with the optimum operation of certain devices based on Fe:LiNbO3. Here, a novel optoelectronic method is proposed and demonstrated to transfer photovoltaic charge patterns from Fe:LiNbO3 to non-photovoltaic passive substrates, thus removing these possible limitations. The method, denominated as photovoltaic charge lithography (PVCL), resembles the operation of a stamp and does not require external high-voltage supplies or electron/ion beams. Upon contact between the active Fe:LiNbO3 stamp and a passive dielectric substrate, the light-induced charge pattern can be faithfully mirrored on the passive substrate. The imprinted pattern is probed and characterized by dielectrophoretic and electrophoretic particle trapping. The results reveal that the charge builds up on the passive substrate during contact, allowing charge tunability. Moreover, arbitrary charge distributions can be flexibly tailored, using scanning laser beams or spatially structured light. Overall, PVCL opens the possibility of printing complex 1D/2D charge patterns of controlled polarity on different passive dielectric materials, enhancing the technological potential of Fe:LiNbO3 photovoltaic platforms. © 2024 The Author(s). Advanced Electronic Materials published by Wiley-VCH GmbH.
11.
González, N.; García, T.; Morant, C.; Barrio, R.
In: Nanomaterials, vol. 14, no. 2, 2024.
@article{gonzalez_fine-tuning_2024,
title = {Fine-Tuning Intrinsic and Doped Hydrogenated Amorphous Silicon Thin-Film Anodes Deposited by PECVD to Enhance Capacity and Stability in Lithium-Ion Batteries},
author = {N. González and T. García and C. Morant and R. Barrio},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85183099095&doi=10.3390%2fnano14020204&partnerID=40&md5=4f64c19b7c393516fe6a90d56122b9fc},
doi = {10.3390/nano14020204},
year = {2024},
date = {2024-01-01},
journal = {Nanomaterials},
volume = {14},
number = {2},
abstract = {Silicon is a promising alternative to graphite as an anode material in lithium-ion batteries, thanks to its high theoretical lithium storage capacity. Despite these high expectations, silicon anodes still face significant challenges, such as premature battery failure caused by huge volume changes during charge–discharge processes. To solve this drawback, using amorphous silicon as a thin film offers several advantages: its amorphous nature allows for better stress mitigation and it can be directly grown on current collectors for material savings and improved Li-ion diffusion. Furthermore, its conductivity is easily increased through doping during its growth. In this work, we focused on a comprehensive study of the influence of both electrical and structural properties of intrinsic and doped hydrogenated amorphous silicon (aSi:H) thin-film anodes on the specific capacity and stability of lithium-ion batteries. This study allows us to establish that hydrogen distribution in the aSi:H material plays a pivotal role in enhancing battery capacity and longevity, possibly masking the significance of the conductivity in the case of doped electrodes. Our findings show that we were able to achieve high initial specific capacities (3070 mAhg-1 at the 10th cycle), which can be retained at values higher than those of graphite for a significant number of cycles (>120 cycles), depending on the structural properties of the aSi:H films. To our knowledge, this is the first comprehensive study of the influence of these properties of thin films with different doping levels and hydrogen distributions on their optimization and use as anodes in lithium-ion batteries. © 2024 by the authors.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Silicon is a promising alternative to graphite as an anode material in lithium-ion batteries, thanks to its high theoretical lithium storage capacity. Despite these high expectations, silicon anodes still face significant challenges, such as premature battery failure caused by huge volume changes during charge–discharge processes. To solve this drawback, using amorphous silicon as a thin film offers several advantages: its amorphous nature allows for better stress mitigation and it can be directly grown on current collectors for material savings and improved Li-ion diffusion. Furthermore, its conductivity is easily increased through doping during its growth. In this work, we focused on a comprehensive study of the influence of both electrical and structural properties of intrinsic and doped hydrogenated amorphous silicon (aSi:H) thin-film anodes on the specific capacity and stability of lithium-ion batteries. This study allows us to establish that hydrogen distribution in the aSi:H material plays a pivotal role in enhancing battery capacity and longevity, possibly masking the significance of the conductivity in the case of doped electrodes. Our findings show that we were able to achieve high initial specific capacities (3070 mAhg-1 at the 10th cycle), which can be retained at values higher than those of graphite for a significant number of cycles (>120 cycles), depending on the structural properties of the aSi:H films. To our knowledge, this is the first comprehensive study of the influence of these properties of thin films with different doping levels and hydrogen distributions on their optimization and use as anodes in lithium-ion batteries. © 2024 by the authors.
12.
Ramírez, M. O.; Molina, P.; Hernández-Pinilla, D.; López-Polín, G.; Ares, P.; Lozano-Martín, L.; Yan, H.; Wang, Y.; Sarkar, S.; Shuhaib, J. H. Al; Leardini, F.; Gómez-Herrero, J.; Chhowalla, M.; Bausá, L. E.
Integrating 2D Materials and Plasmonics on Lithium Niobate Platforms for Pulsed Laser Operation at the Nanoscale Journal Article
In: Laser and Photonics Reviews, vol. 18, no. 1, 2024.
@article{ramirez_integrating_2024,
title = {Integrating 2D Materials and Plasmonics on Lithium Niobate Platforms for Pulsed Laser Operation at the Nanoscale},
author = {M. O. Ramírez and P. Molina and D. Hernández-Pinilla and G. López-Polín and P. Ares and L. Lozano-Martín and H. Yan and Y. Wang and S. Sarkar and J. H. Al Shuhaib and F. Leardini and J. Gómez-Herrero and M. Chhowalla and L. E. Bausá},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85175991331&doi=10.1002%2flpor.202300817&partnerID=40&md5=0dae66d504b276b658d822725bcc9a22},
doi = {10.1002/lpor.202300817},
year = {2024},
date = {2024-01-01},
journal = {Laser and Photonics Reviews},
volume = {18},
number = {1},
abstract = {The current need for coherent light sources for integrated (nano)photonics motivates the search for novel laser designs emitting at technologically relevant wavelengths with high-frequency stability and low power consumption. Here, a new monolithic architecture that integrates monolayer MoS2 and chains of silver nanoparticles on a rare-earth (Nd3+) doped LiNbO3 platform is developed to demonstrate Q-switched lasing operation at the nanoscale. The localized surface plasmons provided by the nanoparticle chains spatially confine the gain generated by Nd3+ ions at subwavelength scales, and large-area monolayer MoS2 acts as saturable absorber. As a result, an ultra-compact coherent pulsed light source delivering stable train pulses with repetition rates of hundreds of kHz and pulse duration of 1 µs is demonstrated without the need of any voltage-driven optical modulation. Moreover, the monolithic integration of the different elements is achieved without sophisticated processing, and it is compatible with LiNbO3-based photonics. The results highlight the robustness of the approach, which can be extended to other 2D materials and solid-state gain media. Potential applications in communications, quantum computing, or ultra-sensitive sensing can benefit from the synergy of the materials involved in this approach, which provides a wealth of opportunities for light control at reduced scales. © 2023 The Authors. Laser & Photonics Reviews published by Wiley-VCH GmbH.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The current need for coherent light sources for integrated (nano)photonics motivates the search for novel laser designs emitting at technologically relevant wavelengths with high-frequency stability and low power consumption. Here, a new monolithic architecture that integrates monolayer MoS2 and chains of silver nanoparticles on a rare-earth (Nd3+) doped LiNbO3 platform is developed to demonstrate Q-switched lasing operation at the nanoscale. The localized surface plasmons provided by the nanoparticle chains spatially confine the gain generated by Nd3+ ions at subwavelength scales, and large-area monolayer MoS2 acts as saturable absorber. As a result, an ultra-compact coherent pulsed light source delivering stable train pulses with repetition rates of hundreds of kHz and pulse duration of 1 µs is demonstrated without the need of any voltage-driven optical modulation. Moreover, the monolithic integration of the different elements is achieved without sophisticated processing, and it is compatible with LiNbO3-based photonics. The results highlight the robustness of the approach, which can be extended to other 2D materials and solid-state gain media. Potential applications in communications, quantum computing, or ultra-sensitive sensing can benefit from the synergy of the materials involved in this approach, which provides a wealth of opportunities for light control at reduced scales. © 2023 The Authors. Laser & Photonics Reviews published by Wiley-VCH GmbH.
13.
Miguel, D.; Cienfueeos, L. Á.; Martín-Lasanta, A.; Morrillo, S. P.; Zotti, L. A.; Leary, E.; Bürkle, M.; Asai, Y.; Jurado, R.; Cárdenas, D. J.; Rubio-Bollinger, G.; Agraït, N.; Cuerva, J. M.; González, M. T.
Toward Multiple Conductance Pathways with Heterocycle-Based Oligo(phenyleneethynylene) Derivatives Book Section
In: Quantum Theory of Transport Properties of Single Molecules, pp. 139–163, 2024.
@incollection{miguel_toward_2024,
title = {Toward Multiple Conductance Pathways with Heterocycle-Based Oligo(phenyleneethynylene) Derivatives},
author = {D. Miguel and L. Á. Cienfueeos and A. Martín-Lasanta and S. P. Morrillo and L. A. Zotti and E. Leary and M. Bürkle and Y. Asai and R. Jurado and D. J. Cárdenas and G. Rubio-Bollinger and N. Agraït and J. M. Cuerva and M. T. González},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85211298899&partnerID=40&md5=f37b7a4b188ea212d1b5177ea62df142},
year = {2024},
date = {2024-01-01},
booktitle = {Quantum Theory of Transport Properties of Single Molecules},
pages = {139–163},
keywords = {},
pubstate = {published},
tppubtype = {incollection}
}
14.
López-Méndez, R.; Dubrova, A.; Reguera, J.; Magro, R.; Esteban-Betegón, F.; Parente, A.; García, M. Ángel; Camarero, J.; Fonda, E.; Wilhelm, C.; Muñoz-Noval, Á.; Espinosa, A.
In: Advanced Healthcare Materials, 2024.
@article{lopez-mendez_multiscale_2024,
title = {Multiscale Thermal Analysis of Gold Nanostars in 3D Tumor Spheroids: Integrating Cellular-Level Photothermal Effects and Nanothermometry via X-Ray Spectroscopy},
author = {R. López-Méndez and A. Dubrova and J. Reguera and R. Magro and F. Esteban-Betegón and A. Parente and M. Ángel García and J. Camarero and E. Fonda and C. Wilhelm and Á. Muñoz-Noval and A. Espinosa},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85211457250&doi=10.1002%2fadhm.202403799&partnerID=40&md5=b108578ec953bcc4b0e7221a86256fa9},
doi = {10.1002/adhm.202403799},
year = {2024},
date = {2024-01-01},
journal = {Advanced Healthcare Materials},
abstract = {In the pursuit of enhancing cancer treatment efficacy while minimizing side effects, near-infrared (NIR) photothermal therapy (PTT) has emerged as a promising approach. By using photothermally active nanomaterials, PTT enables localized hyperthermia, effectively eliminating cancer cells with minimal invasiveness and toxicity. Among these nanomaterials, gold nanostars (AuNS) stand out due to their tunable plasmon resonance and efficient light absorption. This study addresses the challenge of measuring nanoscale temperatures during AuNS-mediated PTT by employing X-ray absorption spectroscopy (XAS) within 3D tumor spheroids. It also aims to investigate the heat generated at the nanoscale and the resultant biological damage observed at a larger scale, utilizing confocal microscopy to establish connections between AuNS heat generation, tissue damage, and their impacts on cellular structure. These nanoscale and microscale thermal effects have been compared with macroscopic values obtained from infrared thermography, as part of a multiscale thermal analysis. The findings underscore the efficacy of AuNS in enhancing PTT and provide insights into the spatial distribution of thermal effects within tumor tissues. This research advances the understanding of localized hyperthermia in cancer therapy and underscores the potential of AuNS-based PTT for clinical applications. © 2024 The Author(s). Advanced Healthcare Materials published by Wiley-VCH GmbH.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In the pursuit of enhancing cancer treatment efficacy while minimizing side effects, near-infrared (NIR) photothermal therapy (PTT) has emerged as a promising approach. By using photothermally active nanomaterials, PTT enables localized hyperthermia, effectively eliminating cancer cells with minimal invasiveness and toxicity. Among these nanomaterials, gold nanostars (AuNS) stand out due to their tunable plasmon resonance and efficient light absorption. This study addresses the challenge of measuring nanoscale temperatures during AuNS-mediated PTT by employing X-ray absorption spectroscopy (XAS) within 3D tumor spheroids. It also aims to investigate the heat generated at the nanoscale and the resultant biological damage observed at a larger scale, utilizing confocal microscopy to establish connections between AuNS heat generation, tissue damage, and their impacts on cellular structure. These nanoscale and microscale thermal effects have been compared with macroscopic values obtained from infrared thermography, as part of a multiscale thermal analysis. The findings underscore the efficacy of AuNS in enhancing PTT and provide insights into the spatial distribution of thermal effects within tumor tissues. This research advances the understanding of localized hyperthermia in cancer therapy and underscores the potential of AuNS-based PTT for clinical applications. © 2024 The Author(s). Advanced Healthcare Materials published by Wiley-VCH GmbH.
15.
Villamiel, M.; Cortés-Avendaño, P.; Ferreira-Lazarte, A.; Condezo-Hoyos, L.
Chemistry of ultrasound processing Book Section
In: Chemistry of Thermal and Non-Thermal Food Processing Technologies, pp. 175–199, 2024.
@incollection{villamiel_chemistry_2024,
title = {Chemistry of ultrasound processing},
author = {M. Villamiel and P. Cortés-Avendaño and A. Ferreira-Lazarte and L. Condezo-Hoyos},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85213539730&doi=10.1016%2fB978-0-443-22182-8.00010-3&partnerID=40&md5=2cbeec51c739a6ac70c0962cad7b9662},
doi = {10.1016/B978-0-443-22182-8.00010-3},
year = {2024},
date = {2024-01-01},
booktitle = {Chemistry of Thermal and Non-Thermal Food Processing Technologies},
pages = {175–199},
abstract = {The increasing demand for high-quality, additive-free foods in the last decades has sparked a growing interest in advanced technologies that can meet this rising demand for top-notch quality products while preserving the original properties of foods. This chapter has delved into the dynamic relationship between nutritional properties and the evolving technologies that are reshaping the realm of food production, particularly ultrasound. The revision here carried out comprises the main general aspects related to the application of ultrasound and the involved mechanisms. We have included the effect of single and intermediate frequency on the main components of food such as lipids, proteins, enzymes, carbohydrates, and bioactive compounds. Special attention has been pain to the impact of intermediate-frequency ultrasound on the functionalization of phenolic moieties. © 2025 Elsevier Inc. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {incollection}
}
The increasing demand for high-quality, additive-free foods in the last decades has sparked a growing interest in advanced technologies that can meet this rising demand for top-notch quality products while preserving the original properties of foods. This chapter has delved into the dynamic relationship between nutritional properties and the evolving technologies that are reshaping the realm of food production, particularly ultrasound. The revision here carried out comprises the main general aspects related to the application of ultrasound and the involved mechanisms. We have included the effect of single and intermediate frequency on the main components of food such as lipids, proteins, enzymes, carbohydrates, and bioactive compounds. Special attention has been pain to the impact of intermediate-frequency ultrasound on the functionalization of phenolic moieties. © 2025 Elsevier Inc. All rights reserved.
16.
Noah, A.; Fridman, N.; Zur, Y.; Markman, M.; King, Y. K.; Klang, M.; Rama-Eiroa, R.; Solanki, H.; Ashby, M. L. R.; Levin, T.; Herrera, E.; Huber, M. E.; Gazit, S.; Santos, E. J. G.; Suderow, H.; Steinberg, H.; Millo, O.; Anahory, Y.
Field-Induced Antiferromagnetic Correlations in a Nanopatterned Van der Waals Ferromagnet: A Potential Artificial Spin Ice Journal Article
In: Advanced Science, 2024.
@article{noah_field-induced_2024,
title = {Field-Induced Antiferromagnetic Correlations in a Nanopatterned Van der Waals Ferromagnet: A Potential Artificial Spin Ice},
author = {A. Noah and N. Fridman and Y. Zur and M. Markman and Y. K. King and M. Klang and R. Rama-Eiroa and H. Solanki and M. L. R. Ashby and T. Levin and E. Herrera and M. E. Huber and S. Gazit and E. J. G. Santos and H. Suderow and H. Steinberg and O. Millo and Y. Anahory},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85211095215&doi=10.1002%2fadvs.202409240&partnerID=40&md5=c6593a196d357a573e8354dbb3f31e74},
doi = {10.1002/advs.202409240},
year = {2024},
date = {2024-01-01},
journal = {Advanced Science},
abstract = {Nano-patterned magnetic materials have opened new venues for the investigation of strongly correlated phenomena including artificial spin-ice systems, geometric frustration, and magnetic monopoles, for technologically important applications such as reconfigurable ferromagnetism. With the advent of atomically thin 2D van der Waals (vdW) magnets, a pertinent question is whether such compounds could make their way into this realm where interactions can be tailored so that unconventional states of matter can be assessed. Here, it is shown that square islands of CrGeTe3 vdW ferromagnets distributed in a grid manifest antiferromagnetic correlations, essential to enable frustration resulting in an artificial spin-ice. By using a combination of SQUID-on-tip microscopy, focused ion beam lithography, and atomistic spin dynamic simulations, it is shown that a square array of CGT island as small as 150 × 150 × 60 nm3 have tunable dipole–dipole interactions, which can be precisely controlled by their lateral spacing. There is a crossover between non-interacting islands and significant inter-island anticorrelation depending on how they are spatially distributed allowing the creation of complex magnetic patterns not observable at the isolated flakes. These findings suggest that the cross-talk between the nano-patterned magnets can be explored in the generation of even more complex spin configurations where exotic interactions may be manipulated in an unprecedented way. © 2024 The Author(s). Advanced Science published by Wiley-VCH GmbH.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Nano-patterned magnetic materials have opened new venues for the investigation of strongly correlated phenomena including artificial spin-ice systems, geometric frustration, and magnetic monopoles, for technologically important applications such as reconfigurable ferromagnetism. With the advent of atomically thin 2D van der Waals (vdW) magnets, a pertinent question is whether such compounds could make their way into this realm where interactions can be tailored so that unconventional states of matter can be assessed. Here, it is shown that square islands of CrGeTe3 vdW ferromagnets distributed in a grid manifest antiferromagnetic correlations, essential to enable frustration resulting in an artificial spin-ice. By using a combination of SQUID-on-tip microscopy, focused ion beam lithography, and atomistic spin dynamic simulations, it is shown that a square array of CGT island as small as 150 × 150 × 60 nm3 have tunable dipole–dipole interactions, which can be precisely controlled by their lateral spacing. There is a crossover between non-interacting islands and significant inter-island anticorrelation depending on how they are spatially distributed allowing the creation of complex magnetic patterns not observable at the isolated flakes. These findings suggest that the cross-talk between the nano-patterned magnets can be explored in the generation of even more complex spin configurations where exotic interactions may be manipulated in an unprecedented way. © 2024 The Author(s). Advanced Science published by Wiley-VCH GmbH.
17.
Ros-Oton, X.; Torres-Latorre, C.; Weidner, M.
Semiconvexity estimates for nonlinear integro-differential equations Journal Article
In: Communications on Pure and Applied Mathematics, 2024.
@article{ros-oton_semiconvexity_2024,
title = {Semiconvexity estimates for nonlinear integro-differential equations},
author = {X. Ros-Oton and C. Torres-Latorre and M. Weidner},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85208922547&doi=10.1002%2fcpa.22237&partnerID=40&md5=cec638291d92ce02b5e8c09d52df1296},
doi = {10.1002/cpa.22237},
year = {2024},
date = {2024-01-01},
journal = {Communications on Pure and Applied Mathematics},
abstract = {In this paper we establish for the first time local semiconvexity estimates for fully nonlinear equations and for obstacle problems driven by integro-differential operators with general kernels. Our proof is based on the Bernstein technique, which we develop for a natural class of nonlocal operators and consider to be of independent interest. In particular, we solve an open problem from Cabré-Dipierro-Valdinoci. As an application of our result, we establish optimal regularity estimates and smoothness of the free boundary near regular points for the nonlocal obstacle problem on domains. Finally, we also extend the Bernstein technique to parabolic equations and nonsymmetric operators. © 2024 The Author(s). Communications on Pure and Applied Mathematics published by Wiley Periodicals LLC.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this paper we establish for the first time local semiconvexity estimates for fully nonlinear equations and for obstacle problems driven by integro-differential operators with general kernels. Our proof is based on the Bernstein technique, which we develop for a natural class of nonlocal operators and consider to be of independent interest. In particular, we solve an open problem from Cabré-Dipierro-Valdinoci. As an application of our result, we establish optimal regularity estimates and smoothness of the free boundary near regular points for the nonlocal obstacle problem on domains. Finally, we also extend the Bernstein technique to parabolic equations and nonsymmetric operators. © 2024 The Author(s). Communications on Pure and Applied Mathematics published by Wiley Periodicals LLC.
18.
Martínez-Ratón, Y.; Velasco, E.
Density-functional theory for clustering of two-dimensional hard particle fluids Journal Article
In: Journal of Molecular Liquids, vol. 397, 2024.
@article{martinez-raton_density-functional_2024,
title = {Density-functional theory for clustering of two-dimensional hard particle fluids},
author = {Y. Martínez-Ratón and E. Velasco},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85184753354&doi=10.1016%2fj.molliq.2024.124044&partnerID=40&md5=7bdb2cda89458c964c163bb6610b926e},
doi = {10.1016/j.molliq.2024.124044},
year = {2024},
date = {2024-01-01},
journal = {Journal of Molecular Liquids},
volume = {397},
abstract = {Fluids made of two-dimensional hard particles with polygonal shapes may stabilize symmetries which do not result directly from the particle shape. This is due to the formation of clusters in the fluid. Entropy alone can drive these effects, which represent a challenge for standard theories. In this article we present a general density-functional theory for clustering effects in fluids of hard particles in two dimensions. The theory combines a free-energy functional of the angular distribution function with an association energy term which qualitatively reproduces the clustering tendencies of the particles found in Monte Carlo simulations. Application is made to a fluid of hard right-angled triangles. © 2024},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Fluids made of two-dimensional hard particles with polygonal shapes may stabilize symmetries which do not result directly from the particle shape. This is due to the formation of clusters in the fluid. Entropy alone can drive these effects, which represent a challenge for standard theories. In this article we present a general density-functional theory for clustering effects in fluids of hard particles in two dimensions. The theory combines a free-energy functional of the angular distribution function with an association energy term which qualitatively reproduces the clustering tendencies of the particles found in Monte Carlo simulations. Application is made to a fluid of hard right-angled triangles. © 2024
19.
Ersu, G.; Munuera, C.; Mompean, F. J.; Vaquero, D.; Quereda, J.; Rodrigues, J. E. F. S.; Alonso, J. A.; Flores, E.; Ares, J. R.; Ferrer, I. J.; Al-Enizi, A. M.; Nafady, A.; Kuriakose, S.; Island, J. O.; Castellanos-Gomez, A.
Low-Cost and Biodegradable Thermoelectric Devices Based on van der Waals Semiconductors on Paper Substrates Journal Article
In: Energy and Environmental Materials, vol. 7, no. 1, 2024.
@article{ersu_low-cost_2024,
title = {Low-Cost and Biodegradable Thermoelectric Devices Based on van der Waals Semiconductors on Paper Substrates},
author = {G. Ersu and C. Munuera and F. J. Mompean and D. Vaquero and J. Quereda and J. E. F. S. Rodrigues and J. A. Alonso and E. Flores and J. R. Ares and I. J. Ferrer and A. M. Al-Enizi and A. Nafady and S. Kuriakose and J. O. Island and A. Castellanos-Gomez},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85146326106&doi=10.1002%2feem2.12488&partnerID=40&md5=a8862d038a9233b578406824e1dc4cd0},
doi = {10.1002/eem2.12488},
year = {2024},
date = {2024-01-01},
journal = {Energy and Environmental Materials},
volume = {7},
number = {1},
abstract = {We present a method to fabricate handcrafted thermoelectric devices on standard office paper substrates. The devices are based on thin films of WS2, Te, and BP (P-type semiconductors) and TiS3 and TiS2 (N-type semiconductors), deposited by simply rubbing powder of these materials against paper. The thermoelectric properties of these semiconducting films revealed maximum Seebeck coefficients of (+1.32 ± 0.27) mV K−1 and (−0.82 ± 0.15) mV K−1 for WS2 and TiS3, respectively. Additionally, Peltier elements were fabricated by interconnecting the P- and N-type films with graphite electrodes. A thermopower value up to 6.11 mV K−1 was obtained when the Peltier element were constructed with three junctions. The findings of this work show proof-of-concept devices to illustrate the potential application of semiconducting van der Waals materials in future thermoelectric power generation as well as temperature sensing for low-cost disposable electronic devices. © 2022 The Authors. Energy & Environmental Materials published by John Wiley & Sons Australia, Ltd on behalf of Zhengzhou University.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We present a method to fabricate handcrafted thermoelectric devices on standard office paper substrates. The devices are based on thin films of WS2, Te, and BP (P-type semiconductors) and TiS3 and TiS2 (N-type semiconductors), deposited by simply rubbing powder of these materials against paper. The thermoelectric properties of these semiconducting films revealed maximum Seebeck coefficients of (+1.32 ± 0.27) mV K−1 and (−0.82 ± 0.15) mV K−1 for WS2 and TiS3, respectively. Additionally, Peltier elements were fabricated by interconnecting the P- and N-type films with graphite electrodes. A thermopower value up to 6.11 mV K−1 was obtained when the Peltier element were constructed with three junctions. The findings of this work show proof-of-concept devices to illustrate the potential application of semiconducting van der Waals materials in future thermoelectric power generation as well as temperature sensing for low-cost disposable electronic devices. © 2022 The Authors. Energy & Environmental Materials published by John Wiley & Sons Australia, Ltd on behalf of Zhengzhou University.
20.
Roldán-Piñero, C.; Luengo-Márquez, J.; Assenza, S.; Pérez, R.
Systematic Comparison of Atomistic Force Fields for the Mechanical Properties of Double-Stranded DNA Journal Article
In: Journal of Chemical Theory and Computation, vol. 20, no. 5, pp. 2261–2272, 2024.
@article{roldan-pinero_systematic_2024,
title = {Systematic Comparison of Atomistic Force Fields for the Mechanical Properties of Double-Stranded DNA},
author = {C. Roldán-Piñero and J. Luengo-Márquez and S. Assenza and R. Pérez},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85186468171&doi=10.1021%2facs.jctc.3c01089&partnerID=40&md5=66ecd9bf962709e2fb0be2e11c7f680f},
doi = {10.1021/acs.jctc.3c01089},
year = {2024},
date = {2024-01-01},
journal = {Journal of Chemical Theory and Computation},
volume = {20},
number = {5},
pages = {2261–2272},
abstract = {The response of double-stranded DNA to external mechanical stress plays a central role in its interactions with the protein machinery in the cell. Modern atomistic force fields have been shown to provide highly accurate predictions for the fine structural features of the duplex. In contrast, and despite their pivotal function, less attention has been devoted to the accuracy of the prediction of the elastic parameters. Several reports have addressed the flexibility of double-stranded DNA via all-atom molecular dynamics, yet the collected information is insufficient to have a clear understanding of the relative performance of the various force fields. In this work, we fill this gap by performing a systematic study in which several systems, characterized by different sequence contexts, are simulated with the most popular force fields within the AMBER family, bcs1 and OL15, as well as with CHARMM36. Analysis of our results, together with their comparison with previous work focused on bsc0, allows us to unveil the differences in the predicted rigidity between the newest force fields and suggests a roadmap to test their performance against experiments. In the case of the stretch modulus, we reconcile these differences, showing that a single mapping between sequence-dependent conformation and elasticity via the crookedness parameter captures simultaneously the results of all force fields, supporting the key role of crookedness in the mechanical response of double-stranded DNA. © 2024 The Authors. Published by American Chemical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The response of double-stranded DNA to external mechanical stress plays a central role in its interactions with the protein machinery in the cell. Modern atomistic force fields have been shown to provide highly accurate predictions for the fine structural features of the duplex. In contrast, and despite their pivotal function, less attention has been devoted to the accuracy of the prediction of the elastic parameters. Several reports have addressed the flexibility of double-stranded DNA via all-atom molecular dynamics, yet the collected information is insufficient to have a clear understanding of the relative performance of the various force fields. In this work, we fill this gap by performing a systematic study in which several systems, characterized by different sequence contexts, are simulated with the most popular force fields within the AMBER family, bcs1 and OL15, as well as with CHARMM36. Analysis of our results, together with their comparison with previous work focused on bsc0, allows us to unveil the differences in the predicted rigidity between the newest force fields and suggests a roadmap to test their performance against experiments. In the case of the stretch modulus, we reconcile these differences, showing that a single mapping between sequence-dependent conformation and elasticity via the crookedness parameter captures simultaneously the results of all force fields, supporting the key role of crookedness in the mechanical response of double-stranded DNA. © 2024 The Authors. Published by American Chemical Society.