Artículos (Física de la Materia Condensada)

URI permanente para esta colecciónhttps://hdl.handle.net/11441/10869

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Effect of Exposure to Blue Light from Electronic Devices and the Mediterranean Diet on Macular Pigment
(MDPI, 2024) García Romera, Marta de la Concepción; Ponce García, Víctor; Torres Parejo, Úrsula; López Muñoz, Alfredo; Universidad de Sevilla. Departamento de Física de la Materia Condensada
Objective: To explore the effect of time exposure to flat screen electronic devices with LED lighting and the Mediterranean diet on macular pigment optical density (MPOD). Methods: In this cross-sectional observational study, the MPOD was measured by heterochromatic flicker photometry in 164 eyes (47 of younger women aged 20–31 and 35 of older women aged 42–70). Exclusion criteria: evidence of macular degeneration and eyes with cataracts. Data on the use of electronic devices and Mediterranean diet adherence were collected through a survey. Nonparametric analysis of variance and independent sample t-tests were used to compare subjects. Results: Significant differences (p < 0.01) were found in total time of exposure to LEDs (hours per day) between both groups (9.31 ± 3.74 younger women vs. 6.33 ± 3.64 older women). The MPOD values for the younger and adult populations were significantly different: 0.38 ± 0.16 and 0.47 ± 0.15 (p < 0.01), respectively. When comparing both groups for the same time of exposure to LEDs, differences were obtained between MPOD values of both populations: For total exposures greater than 6 h per day, the MPOD values were lower in younger women than in adult ones (0.37 ± 0.14 vs. 0.50 ± 0.14, p < 0.01). On the other hand, a significantly higher adherence was found in the older women in comparison with the younger women (OW 9.23 ± 2.50 vs. YW 7.70 ± 2.08, p < 0.01), with higher MPOD values (OW (0.52 ± 0.14) vs. (YW (0.34 ± 0.18). Conclusions: Higher MPOD values are observed with decreasing exposure time to electronic devices with LED lighting screens and higher adherence to the Mediterranean diet.
Microhardness and wear behavior of nanodiamond-reinforced nanocomposites for dental applications
(Wiley, 2024-10-04) Moriche Tirado, Rocío; Chetwani, Bhanu; Artigas-Arnaudas, Joaquín; Sánchez, María; Campo, Mónica; Prolongo, Margarita G.; Rams, Joaquín; Prolongo, Silvia G.; Ureña, Alejandro; Universidad de Sevilla. Departamento de Física de la Materia Condensada; Agencia Estatal de Investigación. España
In polymer-based dental composites, wear is a three-body wear system mainly abrasive, because of the food particles and wear products suspended in the oral cavity, which are transferred to the microcavities of the surface of the replacements. Due to this fact, the incorporation of nanodiamond as reinforcement in these polymer–matrix composites, which promotes the creation of a solid lubricant tribofilm surface could be advantageous. With the reinforcement of nanodiamonds, BisGMA/TEGDMA-based composites increase their microhardness by 95%–420%. A maximum hardness exceeding 65 HV is achieved with a reinforcement of 3.2 wt%. The specific wear rate of neat BisGMA/TEGDMA is near 10−4 mm3/Nm and the Archard's coefficient is 2.6 × 105. The incorporation of a content of 1.6 wt% ND is enough to cause a diminution of ~78% in the friction coefficient and a reduction of the specific wear rate and Archard's coefficient of ~50%. Nevertheless, the addition of relatively high contents reduces the effectiveness of photoinitiation and photocuring, which is related to the scattering and absorption of light radiation by ND. This causes a significant decline in elastic properties starting at 50 μm from the surface.
Fine-grained BCZT piezoelectric ceramics by combining high-energy mechanochemical synthesis and hot-press sintering
(Elsevier, 2024-12-05) Sayagués de Vega, María Jesús ; Otero Pino, Andrea; Santiago Andrades, Lucía; Poyato, R.; Monzón, M.; Paz, R.; Gotor Martínez, Francisco José; Moriche Tirado, Rocío; Universidad de Sevilla. Departamento de Física de la Materia Condensada; Ministerio de Ciencia, Innovación y Universidades (MICINN). España; Agencia Estatal de Investigación. España; European Union (UE)
Different stoichiometries of lead-free BaZr0.2Ti0.8O3–Ba0.7Ca0.3TiO3 (BCZT) prepared by mechanosynthesis and sintered by either conventional sintering (CS) or hot pressing (HP) techniques were studied to establish the dependence of piezoelectric and dielectric properties on sintering parameters and microstructure. All synthesized stoichiometries showed a pseudocubic perovskite phase with homogeneously distributed A- and B-cations in the structure. The BCZT retained the pseudocubic symmetry after sintering and an average grain size <1.8 µm was obtained in all cases. HP sintering hindered the secondary phase segregation observed in the CS ceramics and increased the relative density. Piezoelectric coefficients (d33) ranging from 5.1 to 21 pC/N and from 10.0 to 88.0 pC/N were obtained for CS and HP ceramics, respectively, despite the pseudocubic symmetry and the fine grain size. The higher d33 values for the HP ceramics are a consequence of the higher density, better chemical homogeneity and lower sintering temperature and time required for the mechanosynthesized BCZT powders with high sintering activity.
Seasonal Daylight Saving Time in UK: A long-standing, successful record with few reasons to change
(Wiley, 2024-11-29) Martín Olalla, José María; Mira, Jorge; Universidad de Sevilla. Departamento de Física de la Materia Condensada
Prevalence of sleep disturbance among Chinese healthcare professionals increases Eastward—caution with position in time zone
(Elsevier, 2024-11-19) Martín Olalla, José María; Mira, Jorge; Universidad de Sevilla. Departamento de Física de la Materia Condensada
We analyze data of the prevalence of sleep disturbance among Chinese healthcare professionals and maintain that they increase Eastward, refining previous results. We suggest that position in time zone is a valid explanatory metric only after daily rhythms have been uniformed. On a more general note, this finding suggest that daylight saving time might help reduce sleep disturbance.
Electrochemical Deposition of Manganese Oxide on Paper-Based Laser-Induced Graphene for the Fabrication of Sustainable High-Energy-Density Supercapacitors
(John Wiley & Sons, 2024-07-24) Klem, Maykel dos Santos; Abreu, Rodrigo; Pinheiro, Tomás; Coelho, João; Alves, Neri; Martins, Rodrigo; Universidad de Sevilla. Departamento de Física de la Materia Condensada; São Paulo Research Foundation (FAPESP); Fundação para a Ciên-cia e a Tecnologia; European Union (UE); Junta de Andalucía
Laser-induced graphene (LIG) is widely used to fabricate microsupercapacitors (MSCs) on various sustainable substrates, such as wood, cork, and lignin. However, the fabrication of MSCs, especially high energy density devices on paper, has rarely been reported. In this work, LIG electrodes are fabricated on wax-coated paper, followed by electrochemical deposition of manganese oxide (MnO2). The obtained LIG/MnO2 supercapacitors exhibit a maximum areal capacitance of 86.9 mF cm−2, while a device with pristine LIG electrodes exhibit a capacitance of 9.1 mF cm−2, both measured at a current density of 0.1 mA cm−2. In addition, the supercapacitor exhibits good cycling stability, retaining 80% of its initial capacitance after 1000 charge/discharge cycles at a current density of 1 mA cm−2. Notably, the LIG/MnO2 supercapacitor exhibits an exceptionally high energy density of 7.3 µWh cm−2 at a power density of 38.8 µW cm−2. In summary, a simple, fast, scalable, reproducible, and energy-efficient fabrication method is represented using electrochemical deposition of manganese oxide on paper-based laser-induced graphene, which are natural, abundant, and sustainable materials, paving the way for large-scale production of environmentally friendly supercapacitors.
Multifold Enhanced Photon Upconversion in a Composite Annihilator System Sensitized by Perovskite Nanocrystals
(American Chemical Society, 2024) Chua, Xian Wei; Dai, Linjie; Anaya Martín, Miguel; Salway, Hayden; Ruggeri, Edoardo; Bi, Pengqing; Yang, Zhihong; Stranks, Samuel D.; Yang, Le; Universidad de Sevilla. Departamento de Física de la Materia Condensada; Engineering and Physical Sciences Research Council (UK); European Union (UE). H2020; Ministerio de Ciencia, Innovación y Universidades (MICINN). España; Royal Society. UK; National Research Foundation (NRF). Singapore
Photon upconversion via triplet–triplet annihilation (TTA-UC) provides a pathway to overcoming the thermodynamic efficiency limits in single-junction solar cells by allowing the harvesting of sub-bandgap photons. Here, we use mixed halide perovskite nanocrystals (CsPbX3, X = Br/I) as triplet sensitizers, with excitation transfer to 9,10-diphenylanthracene (DPA) and/or 9,10-bis[(triisopropylsilyl)ethynyl]anthracene (TIPS-An) which act as the triplet annihilators. We observe that the upconversion efficiency is five times higher with the combination of both annihilators in a composite system compared to the sum of the individual single-acceptor systems. Our work illustrates the importance of using a composite system of annihilators to enhance TTA upconversion, demonstrated in a perovskite-sensitized system, with promise for a range of potential applications in light-harvesting, biomedical imaging, biosensing, therapeutics, and photocatalysis.
High-Performance 3D Nanostructured Silver Electrode for Micro-Supercapacitor Application
(American Chemical Society, 2023-10-17) González, Ana Silvia; García, Javier; Vega, Victor; Caballero Flores, Rafael; Prida, Victor M.; Universidad de Sevilla. Departamento de Física de la Materia Condensada; Ministerio de Ciencia, Innovación y Universidades (MICINN). España; Principado de Asturias
In the current energy crisis scenario, the development ofrenewable energy forms such as energy storage systems among the super-capacitors is an urgent need as a tool for environmental protection againstincreasing pollution. In this work, we have designed a novel 3D nanostructuredsilver electrode through an antireplica/replica template-assisted procedure. Thechemical surface and electrochemical properties of this novel 3D electrode havebeen studied in a 5 M KOH electrolyte. Microstructural characterization andcompositional analysis were studied by SEM, energy-dispersive X-ray spectros-copy, XRD technique, and Kripton adsorption at −198 °C, together with cyclicvoltammetry and galvanostatic charge−discharge cycling measurements,Coulombic efficiency, cycle stability, and their leakage current drops, in additionto the self-discharge and electrochromoactive behavior, were performed to fullycharacterize the 3D nanostructured electrode. Large areal capacitance value of 0.5F/cm2 and Coulombic efficiency of 97.5% are obtained at a current density of 6.4 mA/cm2 for a voltage window of 1.2 V (between−0.5 and 0.8 V). The 3D nanostructured silver electrode exhibits excellent capacitance retention (95%) during more than 2600cycles, indicating a good cyclic stability. Additionally, the electrode delivers a high energy density of around 385.87 μWh/cm2 and apower density value of 3.82 μW/cm2 and also displays an electrochromoactive behavior. These experimental results strongly supportthat this versatile combined fabrication procedure is a suitable strategy for improving the electrochemical performances of 3Dnanostructured silver electrodes for applications as micro-supercapacitors or in electrochemical devices
Materials for 3D Printed Metal and Metal-Ion Batteries
(John Wiley & Sons, 2024) García Rodríguez, Tomás; Medina Santos, Jesus I.; Coelho, João; Pinilla, Sergio; Universidad de Sevilla. Departamento de Física de la Materia Condensada; Comunidad Autónoma de Madrid; Junta de Andalucía; Science Foundation Ireland
The review provides an overview of the latest innovations, trends, and challenges in the field of 3D-printed metal and metal-ion batteries. It focuses on the materials used in the printing of batteries, including electrodes, electrolytes, and other electroactive components. Compared to other high-quality reviews on the topic, this review provides a broader selection of materials that are expected to gain attention in the next few years, such as redox-active polymers and metal-organic frameworks. This work gives an overview and insight into the latest trends in printing techniques as well as a statistical review of their uses and strengths. We have also gathered the latest works done for each of the material types, and we have taken the opportunity to put them in context and use them to exemplify in which direction is the field going. The review concludes with a critical view of the challenges ahead and a discussion of the direction that the field is taking as well as the external factors that might help to define its future.
Green Fabrication of Stackable Laser-Induced Graphene Micro-Supercapacitors under Ambient Conditions: Toward the Design of Truly Sustainable Technological Platforms
(John Wiley & Sons, 2024) Silvestre, Sara L.; Morais, Maria; Soares, Raquel R. A.; Johnson, Zachary T.; Benson, Eric; Ainsley, Elisabeth; Pham, Veronica; Claussen, Jonathan C.; Gomes, Carmen L.; Martins, Rodrigo; Fortunato, Elvira; Pereira, Luis; Coelho, João; Universidad de Sevilla. Departamento de Física de la Materia Condensada; Fundação para a Ciência e a Tecnologia. Portugal; European Union (UE); Junta de Andalucía; National Science Foundation (NSF)
Extensive research into green technologies is driven by the worldwide push for eco-friendly materials and energy solutions. The focus is on synergies that prioritize sustainability and environmental benefits. This study explores the potential of abundant, non-toxic, and sustainable resources such as paper, lignin-enriched paper, and cork for producing laser-induced graphene (LIG) supercapacitor electrodes with improved capacitance. A single-step methodology using a CO2 laser system is developed for fabricating these electrodes under ambient conditions, providing an environmentally friendly alternative to conventional carbon sources. The resulting green micro-supercapacitors (MSCs) achieve impressive areal capacitance (≈7–10 mF cm−2) and power and energy densities (≈4 μW cm-2 and ≈0.77 µWh cm−2 at 0.01 mA cm−2). Stability tests conducted over 5000 charge–discharge cycles demonstrate a capacitance retention of ≈80–85%, highlighting the device durability. These LIG-based devices offer versatility, allowing voltage output adjustment through stacked and sandwich MSCs configurations (parallel or series), suitable for various large-scale applications. This study demonstrates that it is possible to create high-quality energy storage devices based on biodegradable materials. This development can lead to progress in renewable energy and off-grid technology, as well as a reduction in electronic waste.
Elucidating the Mechanism of Iron-Catalyzed Graphitization: The First Observation of Homogeneous Solid-State Catalysis
(Wiley, 2024) Hunter, Robert D.; Takeguchi, Masaki; Hashimoto, Ayako; Ridings, Kannan M.; Hendy, Shaun C.; Zakharov, Dmitri; Warnken, Nils; Isaacs, Jack; Fernández Muñoz, Sol; Ramírez Rico, Joaquín; Schnepp, Zoe; Universidad de Sevilla. Departamento de Física de la Materia Condensada; University of Birmingham; Ministerio de Ciencia, Innovación y Universidades (MICINN). España; Junta de Andalucía; ALBA staff
Carbon is a critical material for existing and emerging energy applications and there is considerable global effort in generating sustainable carbons. A particularly promising area is iron-catalyzed graphitization, which is the conversion of organic matter to graphitic carbon nanostructures by an iron catalyst. In this paper, it is reported that iron-catalyzed graphitization occurs via a new type of mechanism that is called homogeneous solid-state catalysis. Dark field in situ transmission electron microscopy is used to demonstrate that crystalline iron nanoparticles “burrow” through amorphous carbon to generate multiwalled graphitic nanotubes. The process is remarkably fast, particularly given the solid phase of the catalyst, and in situ synchrotron X-ray diffraction is used to demonstrate that graphitization is complete within a few minutes
Al2O3/Y3Al5O12 (YAG)/ZrO2 Composites by Single-step Powder Synthesis and Spark Plasma Sintering
(Elsevier, 2024) Vakhshouri, Maryam; Najafzadehkhoee, Aliasghar; Talimian, Ali; López Pernía, Cristina; Poyato, Rosalía; Gallardo López, Ángela María; Gutiérrez Mora, Felipe; Prnova, Anna; Galusek, Dušan; Universidad de Sevilla. Departamento de Física de la Materia Condensada; European Union (UE); JECS Trust
Alumina-yttrium aluminum garnet (YAG)-zirconia composites are often produced by the melt solidification method. In the present study, we investigated the fabrication of α-Al2O3/Y3Al5O12 (YAG)/ZrO2 composite by Spark Plasma Sintering (SPS) of powders synthesized by Pechini's sol-gel method. The ternary composites with homogenous microstructure and high density were produced by SPS at 1300 °C for 15 min. The addition of ZrO2 promoted the sintering of composites, resulting in a higher density and, in turn, higher hardness. A change in the indentation fracture behavior as the result of ZrO2 addition was observed.
Manganese Dioxide Supported on Porous Biomorphic Carbons as Hybrid Materials for Energy Storage Devices
(American Chemical Society, 2016-10) Gutiérrez Pardo, Antonio Anselmo; Lacroix, Bertrand; Martínez Fernández, Julián; Ramírez Rico, Joaquín; Universidad de Sevilla. Departamento de Física de la Materia Condensada; Junta de Andalucía; Ministerio de Economía y Competitividad (MINECO). España
A facile and low-cost method has been employed to fabricate MnO2/C hybrid materials for use as binder-free electrodes for supercapacitor applications. Biocarbon monoliths were obtained through pyrolysis of beech wood, replicating the microstructure of the cellulosic precursor, and serve as 3D porous and conductive scaffolds for the direct growth of MnO2 nanosheets by a solution method. Evaluation of the experimental results indicates that a homogeneous and uniform composite material made of a carbon matrix exhibiting ordered hierarchical porosity and MnO2 nanosheets with a layered nanocrystalline structure is obtained. The tuning of the MnO2 content and crystallite size via the concentration of KMnO4 used as impregnation solution allows to obtain composites that exhibit enhanced electrochemical behavior, achieving a capacitance of 592 F g–1 in electrodes containing 3 wt % MnO2 with an excellent cyclic stability. The electrode materials were characterized before and after electrochemical testing.
Improving Glass-fiber Epoxy Composites Via Interlayer Toughening with Polyacrylonitrile/Multiwalled Carbon Nanotubes Electrospun Fibers
(Wiley, 2023) Narváez Muñoz, Christian; Zamora Ledezma, C.; Ryzhakov, P.; Pons-Prats, J.; Elango, J.; Mena, C.; Navarrete, F.; Morales Flórez, Víctor; Cano Crespo, Rafael; Segura, L. J.; Universidad de Sevilla. Departamento de Física de la Materia Condensada; UCAM. Universidad Católica de Murcia; Ministerio de Ciencia, Innovación y Universidades (MICINN). España
The development of innovative engineered epoxy composites aiming to manufacture cost-efficient materials with reduced weight and enhanced physical properties remains as a current industrial challenge. In this work we report an original procedure for manufacturing glass-fiber epoxy reinforced nanocomposites (GFECs) by employing electrospun fiber-mats as a reinforcing phase. These fibers have been produced from polyacrylonitrile and multiwalled carbon nanotubes solutions. Optimal protocols are designed by combining Taguchi method with the morphological, structural and mechanical properties obtained by scanning electron microscopy, profilometry and tensile tests. It is demonstrated that GFECs fabricated using GF800 glass fiber show an improvement/enhancement of the mechanical properties with a fracture strain up to 500 MPa (around 20% higher than the non-reinforced epoxy composite counterpart). It is also shown that GFECs fabricated using GF3M glass fiber exhibited a reduction of the roughness up to 56%, which corresponds with a roughness improvement from N8 to N7 following the guidelines provided by the ISO 1302. These results suggest that this type of nanocomposites would be suitable to be used in the aeronautics and automotive industries.
Zirconium retention for minimizing environmental risk: Role of counterion and clay mineral
(Elsevier, 2021-03) Montes Montañez, Laura; Pavón González, Esperanza; Cota Reguero, Agustín; Alba Carranza, María Dolores; Universidad de Sevilla. Departamento de Física de la Materia Condensada
Zr(IV) together with U(IV) are the major components of high-level radionuclide waste (HLRW) and spent nuclear fuel (SNF) from nuclear power plants. Thus, their retention in the waste disposal is of great importance for the environmental risk control. Here, the influence of clay minerals on the retention of Zr(IV), as component of the nuclear waste and as chemical analogues of U(IV), has been evaluated. Three clay minerals, two bentonites and one saponite, were hydrothermally treated with three zirconium salts. A structural study at long-range order by X-ray diffraction and short-range order by NMR was performed to evaluate the generation of new zirconium phases and degradation of the clay minerals. Three immobilization mechanisms were observed: i) cation exchange of ZrO2+ or Zr4+ by clay minerals, ii) the precipitation/crystallization of ZrO2, and, iii) the chemical interaction of zirconium with the clay minerals, with the formation of zirconium silicates.
High-Performance 3D Nanostructured Silver Electrode for Micro-Supercapacitor Application
(American Chemical Society, 2023-10-17) González, Ana Silvia; García, Javier; Vega, Víctor; Caballero Flores, Rafael; Prida, Victor M.; Universidad de Sevilla. Departamento de Física de la Materia Condensada; Ministerio de Ciencia e Innovación (MICIN). España; Principado de Asturias
In the current energy crisis scenario, the development of renewable energy forms such as energy storage systems among the supercapacitors is an urgent need as a tool for environmental protection against increasing pollution. In this work, we have designed a novel 3D nanostructured silver electrode through an antireplica/replica template-assisted procedure. The chemical surface and electrochemical properties of this novel 3D electrode have been studied in a 5 M KOH electrolyte. Microstructural characterization and compositional analysis were studied by SEM, energy-dispersive X-ray spectroscopy, XRD technique, and Kripton adsorption at −198 °C, together with cyclic voltammetry and galvanostatic charge–discharge cycling measurements, Coulombic efficiency, cycle stability, and their leakage current drops, in addition to the self-discharge and electrochromoactive behavior, were performed to fully characterize the 3D nanostructured electrode. Large areal capacitance value of 0.5 F/cm2 and Coulombic efficiency of 97.5% are obtained at a current density of 6.4 mA/cm2 for a voltage window of 1.2 V (between −0.5 and 0.8 V). The 3D nanostructured silver electrode exhibits excellent capacitance retention (95%) during more than 2600 cycles, indicating a good cyclic stability. Additionally, the electrode delivers a high energy density of around 385.87 μWh/cm2 and a power density value of 3.82 μW/cm2 and also displays an electrochromoactive behavior. These experimental results strongly support that this versatile combined fabrication procedure is a suitable strategy for improving the electrochemical performances of 3D nanostructured silver electrodes for applications as micro-supercapacitors or in electrochemical devices.
Processing of ZrB2 tribo-ceramics by reactive spark plasma sintering of ZrH2+2B subjected to high-energy pre-ball-milling
(Elsevier, 2023-09) López Arenal, Jesús; Moshtaghion, Bibi Malmal; Gómez García, Diego; Ortiz, Ángel L.; Universidad de Sevilla. Departamento de Física de la Materia Condensada; Ministerio de Ciencia e Innovación (MICIN). España; Junta de Andalucía; Junta de Extremadura
The reactive spark plasma sintering (RSPS) of monolithic ZrB2 ceramics from ZrH2+2B powder mixtures subjected to shaker pre-milling was investigated, and compared with other three sintering approaches. It was found that RSPS is optimal at 1850 °C, which results in fully-dense ZrB2 ceramics with ∼20 GPa hardness. Comparatively, at 1850 °C RSPS from the simply-mixed ZrH2+2B powder mixture, SPS from the commercial ZrB2 powder, and SPS from the shaker-milled ZrB2 powder result in non-dense (76.7–86.7%) and softer (6.0–11.8 GPa) ZrB2 ceramics. Furthermore, the optimally RSPS-ed ZrB2 ceramic was subjected to unlubricated sliding-wear tests against diamond under 40 N load for 1000 m of sliding, demonstrating that it is a promising tribo-ceramic that only undergoes mild tribo-oxidative wear at 10–8 mm3/(N·m) in the form of a slight plasticity-dominated two-body abrasion with eventual formation and partial loss of a self-lubricating and protective oxide tribolayer.
Quantifying structural disorder in spinels by X-ray diffractometry through constrained–restrained Rietveld refinements
(Elsevier, 2023-06) Cumbrera Hernández, Francisco Luis; Moshtaghion, Bibi Malmal; Gómez García, Diego; Ortiz, Ángel L.; Universidad de Sevilla. Departamento de Física de la Materia Condensada; Ministerio de Ciencia e Innovación (MICIN). España; Junta de Andalucía; Junta de Extremadura
Accurate determination of the structural disorder (i.e., cation misplacement, anionic and cationic vacancies, and reduced cations) of spinels is crucial to understanding the properties of this technologically attractive sub-family of ceramics, but it is very difficult to do in practice. Here, constrained–restrained Rietveld refinements of the experimentally measured X-ray diffraction patterns are proposed to tackle the challenging quantification of the structural disorder in spinels. First, it is demonstrated that the constraints–restraints to be imposed during the Rietveld refinements can be formulated by mathematical modelling through the linear inverse problem whose framework is first presented generically and then particularised to the different types of possible normal, inverse, and mixed spinels, namely, stoichiometric perfect spinels, stoichiometric and non-stoichiometric imperfect spinels, and non-stoichiometric imperfect spinels with oxidation state changes. And second, by way of example this type of constrained–restrained Rietveld refinement is successfully applied to the experimental quantification of the structural disorder in two custom-made spinels (i.e., zinc-ferrite and nickel-ferrite spinels).
Review on magnetocaloric high-entropy alloys: design and analysis methods
(Springer, 2023) Law, Jia Yan; Franco García, Victorino; Universidad de Sevilla. Departamento de Física de la Materia Condensada; Ministerio de Ciencia e Innovación (MICIN). España; Junta de Andalucía; Air Force Office of Scientifc Research. United State
The search for high-performance functional alloys with improved service life and reliability entails the optimization of their mechanical properties. Recently, the high-entropy alloy (HEA) design concept has found new alloys with excellent mechanical properties. It utilizes multiprincipal elements to yield high configurational entropy of mixing, entailing a large compositional freedom with wide window of opportunities for property exploration. Their functional properties are usually modest when compared to conventional materials. The discovery of HEAs with optimal combination of mechanical and functional properties would be a leap forward in the reliability of functional devices. This review article focuses on magnetocaloric HEAs, the design approaches, and the appropriate analysis methods for their performance. We will highlight the efficient strategic search within the vast HEA space, which has been instrumental for significantly enhancing MCE performance, closing the pre-existing gap between magnetocaloric HEAs and high-performance conventional magnetocaloric materials. Outlook for future directions will also be included.
Strong angular and spectral narrowing of electroluminescence in an integrated Tamm-plasmon-driven halide perovskite LED
(Springer Nature, 2024-07-10) Ooi, Zher Ying; Jiménez Solano, Alberto; Gałkowski, Krzysztof; Sun, Yuqi; Ferrer Orri, Jordi; Frohna, Kyle; Salway, Hayden; Kahmann, Simon; Nie, Shenyu; Vega Morrone, Guadalupe; Anaya Martín, Miguel; Stranks, Samuel D.; Universidad de Sevilla. Departamento de Física de la Materia Condensada
Next-generation light-emitting applications such as displays and optical communications require judicious control over emitted light, including intensity and angular dispersion. To date, this remains a challenge as conventional methods require cumbersome optics. Here, we report highly directional and enhanced electroluminescence from a solution-processed quasi-2-dimensional halide perovskite light-emitting diode by building a device architecture to exploit hybrid plasmonic-photonic Tamm plasmon modes. By exploiting the processing and bandgap tunability of the halide perovskite device layers, we construct the device stack to optimise both optical and charge-injection properties, leading to narrow forward electroluminescence with an angular full-width half-maximum of 36.6° compared with the conventional isotropic control device of 143.9°, and narrow electroluminescence spectral full-width half-maximum of 12.1 nm. The device design is versatile and tunable to work with emission lines covering the visible spectrum with desired directionality, thus providing a promising route to modular, inexpensive, and directional operating light-emitting devices.

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