Artículos (Física Aplicada I)

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Resonant defect states of the SnO2:Ta transparent conductive oxide revealed by excitation wavelength-dependent Raman spectroscopy and hybrid functional DFT calculations
(Royal Society of Chemistry, 2025-04-01) Krause, Matthias; Romero-Muñiz, Carlos; Selyshchev, Oleksandr; Zahn, Dietrich R. T.; Escobar-Galindo, Ramón; Física de la Materia Condensada; Física Aplicada I
Excitation wavelength-dependent Raman spectroscopy, optical spectroscopy, and density functional theory (DFT) calculations with hybrid functionals were used to analyse the electronic structure of defects in SnO2:Ta (1.25 at% Ta) transparent conductive oxide thin films. Based on the Raman excitation profiles of the characteristic D1 and D2 defect modes of two tin vacancy VSn-type defects and one oxygen interstitial Oi-type defect, we derived the corresponding defect-induced electronic transitions of the involved defect states. DFT calculations revealed additional density-of-states for the three point defects at the top of the valence band (VB) in comparison to defect-free SnO2 and SnO2:Ta. The largest distortion of the VB electronic structure was caused by the VSn-type defect with the farthest possible distance from the Ta dopant in the studied 96-atom supercell, and the smallest distortion was caused by the Oi-type defect. Accordingly, the amount of VB splitting showed a reverse order to the electronic transition energies. From the projected defect-density-of-states, we found a delocalized nature of the VSn-type defects and a localized nature of the Oi-type defect, accounting for the different degrees of distortion of the SnO2:Ta electronic structure. Based on these complementary experimental and theoretical results, the electronic structure of point defects in the SnO2:Ta transparent conductive oxide was elucidated in detail. Thus, the proposed approach has great potential to resolve the ongoing controversy about point defects in SnO2.
Correlation between C-H•••Br and N-H•••Br hydrogen bond formation in perovskite CH3NH3PbBr3: a study based on statistical analysis
(MDPI, 2025-06-04) Garrote Márquez, Alejandro; Cruz Hernández, Norge; Menéndez-Proupin, Eduardo; Física Aplicada I; FQM401: Simulación y Aplicación de Materiales
This study investigates the potential correlation between C—H···Br and N—H···Br hydrogen bonds in CH3NH3PbBr3 over a broad temperature range (50–350 K), using a statistical analysis of molecular dynamics simulations. The analysis focused on quantifying the relationship between both hydrogen bond types via Pearson and Spearman correlation coefficients, derived from extensive datasets obtained from simulation trajectories. The results revealed a notable discrepancy between the two coefficients at low temperatures (T ≤ 125 K): While Spearman’s values suggested a strong monotonic correlation, Pearson’s values indicated a lack of linear association. Further analysis through data segmentation and block averaging demonstrated that the high Spearman coefficients at low temperatures were not statistically robust. At higher temperatures (T > 125 K), both correlation coefficients consistently exhibited low values, confirming the absence of meaningful correlation. These findings suggest that the formation of C–H···Br and N–H···Br hydrogen bonds occurs independently, with no evidence of cooperative behavior.
Further insight in the high selectivity of Pb2+ removal over Cd2 in natural and dealuminated rich-clinoptilolite
(MDPI, 2025-04-27) Durán Avendaño, Yaneth Stephanie; Cruz Hernández, Norge; Ruiz Salvador, Ángel Rabdel; Abatal, Mohamed; Universidad de Sevilla. Departamento de Física Aplicada I; Universidad de Sevilla; Consejo Nacional de Humanidades, Ciencia y Tecnología (CONAHCyT). México; Universidad de Sevilla. FQM401: Simulación y Aplicación de Materiales
This research aims to understand the experimental results on the high selectivity of Pb2+ removal over Cd2+ in natural and dealuminated rich-clinoptilolite. For this purpose, we have considered the results of experimental and Density Functional Theory (DFT)-based simulated annealing (SA) on sorption of Pb2+ and Cd2+ from aqueous solution. The dealumination process of natural clinoptilolite (Nat-CLI) was done by H2SO4 solutions at different concentrations (0.1–1.0 M). The results show that the maximum sorption capacity (q,max) of Pb2+ and Cd2+ varied from 224.554 × 10−3 to 53.827 × 10−3 meq/g, and between 39.044 × 10−3 to 20.529 × 10−3 meq/g, respectively, when the values of Si/Al ratio change from 4.36 to 9.50. From a theoretical point of view, the global minimum energies of natural and dealuminated clinoptilolites before and after sorption of Pb2+ and Cd2+ were calculated by an SA method, where heating-cooling cycles were modeled by ab initio Molecular Dynamics followed by energy minimization. The theoretical results confirmed that for all Si/Al ratios, the sorption of Pb2+ and Cd2+ takes place, and for dealuminated systems, the exchange energy outcomes are more favorable for the Pb2+ cations. Since such energy differences are very small, it is not explained from a thermodynamic point of view. On the other hand, it could be understood from a kinetic perspective. In this way, we set that the atomic structural properties of the zeolite modify the first hydration coordination sphere of metal cations.
Ion Mobility and Segregation in Seed Surfaces Subjected to Cold Plasma Treatments
(American Chemical Society, 2025-02-24) Perea Brenes, Álvaro; Ruiz Pino, Natalia; Yubero, Francisco; Garcia, José Luis; Rodríguez González-Elipe, Agustín; Gómez Ramírez, Ana María; Prados Montaño, Antonio; López Santos, Carmen; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Universidad de Sevilla. Departamento de Física Aplicada I; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; European Union (UE); Universidad de Sevilla; Junta de Andalucía
Plasma treatment of seeds is an efficient procedure to accelerate germination, to improve initial stages of plant growth, and for protection against pathogen infection. Most studies relate these beneficial effects with biochemical modifications affecting the metabolism and genetic growth factors of seeds and young plants. Using barley seeds, in this work, we investigate the redistribution of ions in the seed surface upon their treatment with cold air plasmas. In addition, we investigate the effect of plasma in the lixiviation of ions through the seeds’ hull when they are immersed in water. Ion redistribution in the outer layers of air plasmatreated seeds has been experimentally determined through X-ray photoelectron spectroscopy analysis in combination with in-depth chemical profiling with gas cluster ion beams. The results show that in the shallowest layers of the seed hull (at least up to a depth of ∼100 nm) there is an enrichment of K+ and Ca2+ ions, in addition to changes in the O/C and N/C atomic ratios. These data have been confirmed by the electron microscopy/fluorescence analysis of seed cuts. Observations have been accounted for by a Monte Carlo model, simulating the electrostatic interactions that develop between the negative charge accumulated at the seed surface due to the interaction with the plasma sheath and the positive ions existing in the interior. Furthermore, it is shown that upon water immersion of plasma-treated seeds mobilized ions tend to lixiviate more efficiently than in pristine seeds. The detection of a significant concentration of NO3− anions in the water has been attributed to a secondary reaction of nitrogen species incorporated into the seeds during plasma exposure with reactive oxygen species formed on their surface during this treatment. The implications of these findings for the improvement of the germination capacity of seeds are discussed.
210Pb-based dating models for recent sediments. A review
(Elsevier, 2025-10) Abril Hernández, José María; Universidad de Sevilla. Departamento de Física Aplicada I; Universidad de Sevilla. RNM138: Física Nuclear Aplicada
The 210Pb-based dating method provides absolute ages determination in recent aquatic sediments at centennial scales. It is widely used to support a large variety of environmental studies. However, any empirical data set is compatible with an infinite number of chronologies that need to be constrained by a series of assumptions (models) on the particular sedimentary conditions of the studied environment, and validated with independent chronostratigraphic markers. During five decades, about thirty models have been developed to cope with the wide diversity of natural conditions, a good number of them appearing in recent years, along with new concepts such as model errors, attractors for χ-mapping, or kinetic reactive transport, which have changed common views and practices. This paper aims to present a comprehensive review of this dating method to provide to final users updated tools and a renewed understanding to improve the reliability of their applications. Models are classified in terms of their assumptions on the sedimentary systems, which are better understood from a revisited theory of early compaction and the description of the microcosms of saturated porous media, where composite fluxes of tracers undergo different deposition pathways in terms of physical and kinetic reactive transport. The article reviews empirical evidence on the natural variability in mass flows and initial activity concentrations. Some models allow analytical solutions, while others require numerical techniques. The review is illustrated with examples from real case studies.
A symmetry-based multimodal transfer-matrix method for the analysis of 2D-periodic structures
(Institute of Electrical and Electronics Engineers, 2025) Jiménez Suárez, Jesús María; Mesa Ledesma, Francisco Luis; Universidad de Sevilla. Departamento de Física Aplicada I; Horizon Europe Research and Innovation Program
We propose a systematic and efficient extension of the multimodal transfer-matrix method to obtain the dispersion diagram of structures with 2-D periodicity specifically targeted to primitive unit cells that possess internal symmetries. When symmetry planes can be applied, the study of the unit cell can be simplified to a number of 1D-periodic scenarios that depend on the boundary conditions imposed by the symmetry planes. The study of these 1D-periodic scenarios is simpler, more accurate, and requires less computational cost. The proposed methodology has been validated with different examples of periodic structures with different lattices (squared, rectangular, and hexagonal), symmetries, and motifs. Furthermore, this approach brings about a deeper understanding of the study of the Brillouin zone (BZ) and the relationship between phase shift and paths on its irreducible Brillouin zone (IBZ).
Characterization and Suppression of Transmission Dips in Glide-Symmetric Holey Gap Waveguides
(Institute of Electrical and Electronics Engineers, 2025-06-03) Chen, Mingzheng; Bellbrant, Johan; Zetterstrom, Oskar; Mesa Ledesma, Francisco Luis; Quevedo Teruel, Óscar; Universidad de Sevilla. Departamento de Física Aplicada I; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Universidad de Sevilla. TIC112: Microondas
The spurious transmission dips that occur in glide-symmetric holey gap waveguides (GSHGWs) are systematically characterized in this work, and the obtained information is used to suppress them in the intended operating band of the gap waveguide. The analysis relies on the dispersion characteristics of the waveguide segment with electromagnetic bandgap (EBG) holes. These characteristics are explored through the multimodal transfer matrix approach, particularly focusing on identifying relevant edge and waveguide modes. We find four types of unwanted dips in the transmission coefficient within the intended operation frequency band of the gap waveguide under study. The first three types are all associated with the edge mode mostly concentrated in the small air-gap region between the waveguide and the EBG holes, whereas the fourth type is caused by a narrow stopband in the waveguide mode. Based on a thorough understanding of all dips, we propose three viable solutions: placing EBG holes away from the waveguide channel, intersecting EBG holes with the waveguide channel, and intersecting additional small holes with the waveguide channel and the EBG holes. After comparison, the last solution with two small holes per EBG hole along the waveguide channel was demonstrated to be the most advantageous in terms of transmission properties, compactness, and flexibility. This solution was also experimentally validated using a WR-19 GSHGW operating from 35 to 63 GHz.
On the proximity of Ablowitz–Ladik and discrete nonlinear Schrödinger models: A theoretical and numerical study of Kuznetsov-Ma solutions
(Elsevier, 2025-08) Lytle, Madison L.; Charalampidis, Efstathios G.; Mantzavinos, Dionyssios; Cuevas-Maraver, Jesús; Kevrekidis, Panayotis G.; Karachalios, Nikos I.; Universidad de Sevilla. Departamento de Física Aplicada I; National Science Foundation (NSF). United States; European Union (UE); Universidad de Sevilla. FQM280: Física no Lineal
In this work, we investigate the formation of time-periodic solutions with a non-zero background that emulate rogue waves, known as Kuznetsov-Ma (KM) breathers, in physically relevant lattice nonlinear dynamical systems. Starting from the completely integrable Ablowitz–Ladik (AL) model, we demonstrate that the evolution of KM initial data is proximal to that of the non-integrable discrete Nonlinear Schrödinger (DNLS) equation for certain parameter values of the background amplitude and breather frequency. This finding prompts us to investigate the distance (in certain norms) between the evolved solutions of both models, for which we rigorously derive and numerically confirm an upper bound. Finally, our studies are complemented by a two-parameter (background amplitude and frequency) bifurcation analysis of numerically exact, KM-type breather solutions of the DNLS equation. Alongside the stability analysis of these waveforms reported herein, this work additionally showcases potential parameter regimes where such waveforms with a flat background may emerge in the DNLS setting.
Design of Broadband Aperture-Coupled Microstrip Antenna Arrays With Differential Feeding
(Institute of Electrical and Electronics Engineers Inc., 2024) Delgado Lozano, Ignacio María; Fernández Prieto, Armando; Losada Torres, Vicente; Boix, R. R.; Medina Mena, Francisco; Universidad de Sevilla. Departamento de Electrónica y Electromagnetismo; Universidad de Sevilla. Departamento de Física Aplicada I; Ministerio de Ciencia, Innovación y Universidades (MICIU). España
This paper proposes the design of broadband microstrip antennas fed by differential microstrip lines. The designed broadband antennas are composed of two capacitively coupled rectangular stacked patches excited through a dog-bone shaped aperture by short-circuited differential microstrip lines. The short-circuited lines are symmetrically located with respect to the apertures so that their differential-mode (DM) naturally excites the aperture, while their common-mode (CM) is intrinsically rejected. The DM design of the antennas is based on an equivalent second-order filter circuit consisting of two capacitively coupled parallel LC resonators, which helps to ensure the DM broadband impedance matching of the antenna. Two different 2 × 2 arrays using the proposed antennas have been designed, fabricated and measured, one involving four 180° hybrids and three power dividers in the feeding network, the other involving one 180° hybrid and six power dividers. Bandwidths larger than 25%, gains around 12 dBi and cross-polarization below -25 dB have been achieved by the two arrays at a center frequency of 5.5 GHz.
Multidimensional nanoarchitectures for improved indoor light harvesting in dye-sensitized solar cells
(Elsevier, 2025-04) Castillo Seoane, Javier; Contreras Bernal, Lidia; Riquelme Expósito, Antonio Jesús; Fauvel, Samuel; Kervella, Yann; Gil Rostra, Jorge; Lozano Barbero, Gabriel Sebastián; Barranco Quero, Ángel; Demadrille, Renaud; Sánchez Valencia, Juan Ramón; Borrás Martos, Ana Isabel; Universidad de Sevilla. Departamento de Física Aplicada I; Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte; Consejo Superior de Investigaciones Científicas (CSIC); European Union (UE). H2020; Universidad de Sevilla. TEP123: Metalurgia e Ingeniería de los Materiales
Dye Sensitized Solar Cells (DSSCs) have recently gained renewed interest for their potential in indoor light harvesting and powering wireless devices. However, to fully exploit their potential, crucial aspects require further attention, in particular, the improvement of spectral compatibility and low-light harvesting mechanisms, as well as the development of efficient photoanodes through high-yield scalable methods. In this article, we propose the use of nanocomposite photoanodes integrating mesoporous TiO2 nanoparticles, ITO nanotubes (NT), and anatase TiO2 shells (ITO@TiO2 NT) prepared by step-by-step method relying on mild temperature conditions and avoiding toxic precursors. These photoanodes outperform previous attempts to implement low-dimensional ITO and ITO@TiO2 nanowires and nanotubes for outdoor light conversion, demonstrating a power conversion efficiency under low artificial light intensity of 24 % for at 0.014 mW cm−2, a 166 % increase compared to the conventional architectures. Advanced microstructural, optical, and electrochemical characterizations have revealed that the strong scattering effect of the light in the visible range coupled with enhanced charge collection at low-intensity illumination are the essential mechanisms responsible for such enhanced energy conversion. Remarkably, our devices retain up to 90 % of the normal incidence efficiency even under glancing illumination, while conventional reference devices retain only 30 %.
Triboelectric pixels as building blocks for microscale and large-area integration of drop energy harvesters
(Cell Press, 2024-10-03) Ghaffarinejad, Ali; García Casas, Xabier; Núñez-Gálvez, Fernando; Budagosky Marcilla, Jorge Alejandro; Fortio Godinho, Vanda Cristina; López Santos, Carmen; Sánchez Valencia, Juan Ramón; Barranco Quero, Ángel; Borrás, Ana; Universidad de Sevilla. Departamento de Electrónica y Electromagnetismo; Universidad de Sevilla. Departamento de Física Aplicada I; Ministerio de Ciencia e Innovación (MICIN). España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Universidad de Sevilla; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; European Union (UE). H2020
Triboelectric nanogenerators (TENGs) are the most promising technology for harvesting energy from low-frequency liquid flows and impacts such as rain droplets. However, current drop energy harvester technologies suffer from low output power due to limitations in triboelectric materials, suboptimal device designs, and the inability to fully capture the kinetic energy of falling drops. This article introduces a microscale TENG capable of efficiently converting drop impact energy into electrical power in a single, rapid step. The device features a capacitive structure that enhances energy conversion through instantaneous capacitance changes when the drops contact the submillimetric top electrodes. This compact design establishes a path toward the development of dense arrays and rain panels and is adaptable to various liquids, scales, triboelectric surfaces, and thin-film configurations, including flexible and transparent materials.
Compositional and microstructural study of joining methods in archaeological gold objects
(John Wiley and Sons Ltd, 2017-03) Scrivano, Simona; Gómez-Tubio, Blanca María; Ortega-Feliú, Inés; Ager Vázquez, Francisco José; Paúl Escolano, Antonio; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Universidad de Sevilla. Departamento de Física Aplicada III; Universidad de Sevilla. Departamento de Física Aplicada I; Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Economía y Competitividad (MINECO). España
This work arises in response to the need to understand the production techniques of pre-roman gold jewels, starting from the systematic characterization of the different methods of metal joining used in antiquity to produce these objects. To meet this requirement, different procedures used in antiquity were reproduced by means of experimental archaeology. These models correspond to three metal-joining methods reported by ancient recipes: solid-state diffusion with copper salt, brazing and autogenous welding. These techniques were studied by different analytical methods in order to characterize them at both compositional and microstructural level (SEM-EDS, metallography, μ-XRF and μ-PIXE). The results obtained show that the solid-state diffusion bonding with copper salt presents a crystal hexagonal structure without phase changes in the joining point, where only a variation in the grain size is observed. At the compositional level, this soldering method is characterized by a local increase in copper concentration and a small decrease in gold content. In contrast, brazing shows a dendritic-porous structure due to the superposition of the soldering alloy and the crystal structure of the original foils. Besides, the compositional analysis revealed an increment of silver and copper concentrations and a simultaneous reduction of gold concentration. Finally, in the autogenous welding, no changes at the microstructural and compositional levels were observed. The results obtained have also demonstrated the usefulness of a portable μ-XRF system for the in-situ characterization of ancient jewels.
Combining XRF and GRT for the analysis of ancient silver coins
(Elsevier, 2016-05) Ager Vázquez, Francisco José; Gómez-Tubio, Blanca María; Paúl Escolano, Antonio; Gómez-Morón, A.; Scrivano, Simona; Ortega-Feliú, Inés; Respaldiza Galisteo, Miguel Ángel; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Universidad de Sevilla. Departamento de Física Aplicada I; Universidad de Sevilla. Departamento de Física Aplicada III; Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Economía y Competitividad (MINECO). España
Archaeological silver-copper alloys are usually affected by silver enrichment of the near surface layers, either intentional or fortuitous. In previous studies we have shown that surface composition of archaeological bronzes and leaded copper coins obtained by XRF can be corrected by means of gamma-ray transmission (GRT) to obtain the bulk composition. In the present work, we have studied the applicability of this method to silver-copper alloys and established the most suitable conditions for the GRT correction calculation. The analysis of the microstructure of the core and the corrosion layers of a set of silver roman coins shows that copper could be leached from the surface during corrosion and cleaning treatments, resulting in an apparent silver surface enrichment. After the correction calculations by GRT method, the concentrations of the major elements, Ag and Cu, were found to be in good agreement with the bulk composition obtained by direct analysis of the cut cross-sections of the coins. The GRT method shows to be a useful tool to study metal artefacts having a surface composition modified by corrosion or cleaning treatments.
The complete solution of the Schrödinger equation with the Rosen–Morse type potential via the Nikiforov–Uvarov method
(Elsevier, 2024-02) Gordillo Núñez, Guillermo; Álvarez Nodarse, Renato; Quintero, Niurka R.; Universidad de Sevilla. Departamento de Física Aplicada I; Ministerio de Ciencia e Innovación (MICIN). España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Junta de Andalucía; Universidad de Granada; Andalusian research group; Universidad de Sevilla. FQM415: Modelado Físico-Matemático de Sistemas no Lineales
We determine exact solutions of the time-independent Schrödinger equation for the Rosen–Morse type potential by using the Nikiforov–Uvarov method. This method allows us to write the eigenfunctions of the Schrödinger equation as the product of two simpler functions in a constructive way. The resolution of this problem is used to show that the kinks of the non-linear Klein–Gordon equation with 𝜑2𝑝+2 type potentials are stable. We also derive the orthogonality and completeness relations satisfied by the set of eigenfunctions, which are useful in the description of the dynamics of kinks under perturbations or interacting with antikinks.
Picosecond lifetimes of hydrogen bonds in the halide perovskite CH₃NH₃PbBr₃
(American Chemical Society, 2024-11-26) Garrote Márquez, Alejandro; Lodeiro Moraga, Lucas; Cruz Hernández, Norge; Liang, Xia; Walsh, Aron; Menéndez-Proupin, Eduardo; Universidad de Sevilla. Departamento de Física Aplicada I; Universidad de Sevilla. FQM401: Simulación y Aplicación de Materiales
The structures and properties of organic–inorganic perovskites are influenced by the hydrogen bonding between the organic cations and the inorganic octahedral networks. This study explores the dynamics of hydrogen bonds in CH3NH3PbBr3 across a temperature range from 70 to 350 K, using molecular dynamics simulations with machine-learning force fields. The results indicate that the lifetime of hydrogen bonds decreases with increasing temperature from 7.6 ps (70 K) to 0.16 ps (350 K), exhibiting Arrhenius-type behavior. The geometric conditions for hydrogen bonding, which include bond lengths and angles, maintain consistency across the full temperature range. The relevance of hydrogen bonds for the vibrational states of the material is also evidenced through a detailed analysis of the vibrational power spectra, demonstrating their significant effect on the physical properties for this class of perovskites.
Investigación multidisciplinar basada en el uso de aceleradores de partículas: el Centro Nacional de Aceleradores
(Fundación General de la Universidad Autónoma de Madrid, 2024-09) López Gutiérrez, José María; García-Tenorio García-Balmaseda, Rafael; Universidad de Sevilla. Departamento de Física Aplicada I; Universidad de Sevilla. RNM138: Física Nuclear Aplicada
En este artículo se lleva a cabo un análisis descriptivo a distintos niveles del Centro Nacional de Aceleradores, dedicado fundamentalmente a la realización de investigaciones multidisciplinares basadas en el uso de aceleradores de partículas y equipos asociados. En el artículo se hace así referencia a las seis instalaciones principales que posee este centro y a las distintas líneas de investigación asociadas a ellas. Igualmente se describe la estructura de recursos personales que posee, y que integra un conjunto de sesenta personas, mencionándose igualmente las características orientadas a los usuarios externos del centro a través de las actividades de carácter transversal que desarrolla y a las colaboraciones estratégicas con empresas e instituciones que viene poniendo en práctica en los últimos años.
Metal-only additive manufacturing of V-band lightweight waveguide and horn components
(Institute of Electrical and Electronics Engineers, 2024-09) Chen, Mingzheng; Rico Fernández, José; Mesa Ledesma, Francisco Luis; Quevedo Teruel, Óscar; Universidad de Sevilla. Departamento de Física Aplicada I; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Universidad de Sevilla. TIC112: Microondas
Additive manufacturing (AM) is growing as a key technology for the miniaturization and integration of microwave components. Among several AM processes, laser powder-bed fusion (LPBF) is especially convenient for waveguides and horns because it allows for 3-D printing of metal-only parts with high accuracy and low surface roughness. During the 3-D printing process, metallic powder materials are selectively consolidated by melting layer by layer together using a heat source, that is, a laser, allowing for adaptation to complex and shaped structures. The present study investigates the feasibility of using LPBF-AM to fabricate waveguides and geodesic H-plane horns in V-band. Geodesic H-plane horns comprise two parallel curved metallic plates to reduce phase errors and achieve high gain and aperture efficiency, and are particularly suited to be fabricated using LPBF. The monolithic waveguides demonstrate significantly better performance than their two-piece counterparts, achieving an average attenuation coefficient of 5.3 dB/m for the straight waveguide and 8 dB/m for the 90° E-plane waveguide bend at 50–70 GHz. Similarly, the monolithic geodesic H-plane horn has higher realized gains and radiation efficiencies with only a sixth of the weight compared to the two-piece version at 52–68 GHz. The results demonstrate that the LPBF-AM technique is a promising candidate to produce monolithic metal-only microwave components in V-band.
Theory and design of waveguide dual polarization-plane rotators based on rotational corrugations
(Institute of Electrical and Electronics Engineers, 2024-11) García Contreras, Ginés; Mesa Ledesma, Francisco Luis; Córcoles Ortega, Juan; Ruiz Cruz, Jorge Alfonso; Quevedo Teruel, Óscar; Universidad de Sevilla. Departamento de Física Aplicada I; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Universidad de Sevilla. TIC112: Microondas
This work presents a framework for the introduction of reciprocal dual polarization-plane rotators in waveguide technology. This concept is presented using rotational and longitudinal unit cells (rotational corrugations), stating rigorously the geometrical constraints required for its implementation. The devices have been studied from both a linear and a circular polarization modal perspective, using a mode-matching technique for rotationally symmetric modes and dispersion diagrams. Furthermore, various devices that use the proposed scheme have been designed to show the operation principle. A prototype has been built using additive manufacturing as a proof of concept. It has been measured using dedicated ortho-mode transducers (OMTs) for extracting the different involved signals and fully characterizing their performance.
Numerical modelling of higher-symmetric periodic structures with hexagonal lattice
(Institute of Electrical and Electronics Engineers, 2024-11) Petek, Martin; Rico Fernández, José; Tobón Vásquez, Jorge Alberto; Valerio, Guido; Mesa Ledesma, Francisco Luis; Quevedo Teruel, Óscar; Vipiana, Francesca; Universidad de Sevilla. Departamento de Física Aplicada I; European Cooperation in Science and Technology (COST); Ministerio de Ciencia e Innovación (MICIN). España; Universidad de Sevilla. TIC112: Microondas
This paper presents the development of the multi-modal transfer matrix method (MMTMM) to deal with periodic structures with hexagonal unit cells and higher symmetries. The method is able to calculate complex modal solutions, including the attenuation in the stopband. A key feature is the reformulation of the MMTMM into an eigenvalue problem whose eigensolutions in the complex plane can be systematically obtained for the boundaries of the irreducible Brillouin zone, where the phase-shift conditions are linearly dependent. The obtained phase-shift dispersion diagrams are verified against a commercial software, while the attenuation constant is validated with a developed method of moments. A glide-symmetric structure and a mirror half-turn structure are investigated. The latter is found to possess a highly isotropic stopband with a fractional bandwidth of 94.9%, wider than previously reported for holey structures. Finally, the operation of the unit cell is demonstrated with a practical implementation for preventing leakage in a waveguide flange.
Mechanisms of de-icing by surface rayleigh and plate lamb acoustic waves
(Wiley, 2024-12) Pandey, Shilpi; Moral Jalón, Jaime del; Jacob, Stefan; Montes Montañez, Laura; Gil Rostra, Jorge; Frechilla Zabal, Alejandro; Karimzadeh, Atefeh; Rico-Gavira, Víctor Joaquín ; Kanter, Raul; Kandelin, Niklas; López Santos, Carmen; Koivuluoto, Heli; Angurel Lambán, Luis Alberto; Winkler, Andreas; Borrás Martos, Ana Isabel; Rodríguez González-Elipe, Agustín; Universidad de Sevilla. Departamento de Física Aplicada I; Agencia Estatal de Investigación. España; European Union (UE). H2020
Acoustic waves (AW) have recently emerged as an energy-efficient ice-removal procedure compatible with functional and industrial-relevant substrates. However, critical aspects at fundamental and experimental levels have yet to be disclosed to optimize their operational conditions. Identifying the processes and mechanisms by which different types of AWs induce de-icing are some of these issues. Herein, using model LiNbO3 systems and two types of interdigitated transducers, the e-icing and anti-icing efficiencies and mechanisms driven by Rayleigh surface acoustic waves (R-SAW) and Lamb waves with 120 and 510 μm wavelengths, respectively, are analyzed. Through the experimental analysis of de-icing and active anti-icing processes and the finite element simulation of the AW generation, propagation, and interaction with small ice aggregates, it is disclosed that Lamb waves are more favorable than R-SAWs to induce de-icing and/or prevent the freezing of small ice droplets. Prospects for applications of this study are supported by proof of concept experiments, including de-icing in an icing wind tunnel, demonstrating that Lamb waves can efficiently remove ice layers covering large LN substrates. Results indicate that the de-icing mechanism may differ for Lamb waves or R-SAWs and that the wavelength must be considered as an important parameter for controlling the efficiency.

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