Artículos SCI
2022
2022
Materiales Nanoestructurados y Microestructura
Morphologically diverse CaCO3 microparticles and their incorporation into recycled cellulose for circular economy
Guerra-Garces, J; Garcia-Negrete, CA; Pastor-Sierra, K; Arteaga, GC; Barrera-Vargas, M; de Haro, MJ; Fernandez, AMaterials Today Sustainability, 19 (2022) 100166
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The main raw material for manufacture of paper is cellulose fibers that can be virgin or recycled. Globally, 70% of the Tetra Pak packages sold are not recycled and remain as unused wastes. Therefore, the development of alternatives to promote greater recycling and sustainable use of these packages is of great interest. In this study, the formation of precipitated calcium carbonates (PCC) in the presence of carboxymethyl cellulose (CMC) is studied at different temperatures, and the morphologically diverse particles obtained are explored as filler for composites based on cellulosic fibers recovered from Tetra Pak containers. It was found that the addition of filler does not lead to deterioration of either tensile strength or thermal and stability of the obtained composite samples. Results also suggest that the morphological diversity of the filler contributes to a more efficient filling of the interfibrillar spaces of cellulosic fibers and, in turn, to the fiber and filler compatibility.
Noviembre, 2022 | DOI: 10.1016/j.mtsust.2022.100166
Reactividad de Sólidos
Supercooled sodium acetate aqueous solution for long-term heat storage to support heating decarbonisation
Lizana, J; Sanchez-Jimenez, PE; Chacartegui, R; Becerra, JA; Perez-Maqueda, LAJournal of Energy Storage, 55 (2022) 105584
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Heating decarbonisation through electrification requires the development of novel heat batteries. They should be suitable for the specific application and match the operation conditions of domestic renewable energy sources. Supercooled liquids, often considered a drawback of phase change materials, are among the most promising technologies supporting heating decarbonisation. Although some studies have shed light on stable supercooling, the fundamentals and stability remain open problems not always accompanied by relevant experimental in-vestigations. This research critically analyses the physic and chemistry of sodium acetate (SA, NaCH3COO) aqueous solution, a low-cost, non-toxic, and abundant compound with stable supercooling for long-term heat storage. It has an appropriate phase change temperature for high-density heat storage using heat pumps or solar thermal technologies in residential applications. The existing discrepancies in literature are critically discussed through a systematic experimental evaluation, providing novel insights into efficient material design and appropriate boundary conditions for reliable material use in long-term heat batteries. Despite previous studies showing that the thermal reliability and stability of sodium acetate aqueous solution as a supercooled liquid for heat storage cannot be guaranteed, this study demonstrates that through an appropriate encapsulation and sealing method, the peritectic composition of sodium acetate solution (p-SA 58 wt%) can be used as a super-cooled liquid for long-term heat storage with a stable melting temperature of 57 degrees C, appropriate for domestic heat technologies. It is demonstrated that energy storage efficiency can be maintained under cycling, with a constant latent heat storage capacity of 245 kJ/kg and a volumetric storage density of 314 MJ/m3. It was confirmed that the material should achieve a fully-melted state for stable supercooling. Finally, local cooling and retaining seed crystals through high pressure were highlighted as the most suitable basic principles for successful crystallization and heat release. This promising material can store energy for long periods without latent heat losses due to its stable subcooling. Latent heat can be released when required at any selected time and tem-perature just by a simple activation process.
Noviembre, 2022 | DOI: 10.1016/j.est.2022.105584
Materiales Ópticos Multifuncionales
Nanoantennas Patterned by Colloidal Lithography for Enhanced Nanophosphor Light Emission
Viana, JM; Romero, M; Lozano, G; Míguez, HACS Applied Nano Materials, 5(11) (2022) 16242-16249
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![](https://icms.us-csic.es/sites/icms.us-csic.es/files/an2c03258_0006.png)
Transparent coatings made of rare-earth doped nanocrystals, also known as nanophosphors, feature efficient photoluminescence and excellent thermal and optical stabi l i t y . Herein, we demonstrate that the optical antennas prepared by colloidal lithography render thin nanophosphor films with a brighter emission. In particular, we fabricate gold nanostructures in the proximity of GdVO4:Eu3+ nanophosphors by metal evaporation using a mask made of a monolayer of polymer beads arranged in a triangular lattice. Optical modes supported by the antennas can be controlled by tuning the diameter of the polymer spheres in the colloidal mask, which determines the shape of the gold nanostructure, as confirmed by numerical simulations. Confocal microscopy reveals that metallic antennas induce brighter photoluminescence at specific spatial regions of the nanophosphor film at targeted frequencies as a result of the coupling between gold nanostructures and nanophosphors. Patterning of nanophosphor thin layers with arrays of metallic antennas offers an inexpensive nanophotonic solution to develop bright emitting coatings of interest for color conversion, labeling , or anti-counterfeiting.
Noviembre, 2022 | DOI: 10.1021/acsanm.2c03258
Reactividad de Sólidos
Reactive flash sintering of SrFe12O19 ceramic permanent magnets
Manchon-Gordon, AF; Sanchez-Jimenez, PE; Blazquez, JS; Perejon, A; Perez-Maqueda, LAJournal of Alloys and Compounds, 922 (2022) 166203
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Reactive flash-sintering technique has been used in order to obtain strontium ferrite magnets from a mixture of SrCO3 and Fe2O3 commercial powders. This technique allows preparing sintered SrFe12O19 at a furnace temperature of just 973 K during just 2 min by applying a modest field of 40 V cm(-1), instead of the conventional sintering process employed in ferrite magnet manufacturing that demands high temperature and long dwell times. Analysis of structural and magnetic properties were performed as a function of time in which the flash event was held. Mossbauer spectra show the existence of five different kinds of local environments, confirming the formation of strontium hexaferrite. The resulting samples exhibit comparable magnetic properties to the state-of-the-art ferrite magnets. In particular, produced samples reach a coercivity of 0.4 T and a specific saturation magnetization of 70 Am-2 kg(-1).
Noviembre, 2022 | DOI: 10.1016/j.jallcom.2022.166203
Materiales de Diseño para la Energía y Medioambiente
Exploring the local environment of the engineered nanoclay Mica-4 under hydrothermal conditions using Eu(3+)as a luminescent probe
Martin-Rodriguez, R; Aguado, F; Alba, MD; Valiente, R; Pavon, E; Perdigon, ACJournal of Alloys and Compounds, 921 (2022) 166086
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![](https://icms.us-csic.es/sites/icms.us-csic.es/files/1-s2_367.png)
High charge mica Na4Al4Si4Mg6O20F4 , Mica-4, is a promising candidate as a filling material to immobilize high-level radioactive waste in deep geological repositories due to its extraordinary adsorption capacity. In contrast to traditional clay materials, the structural composition of this mica, with a high content of alu-minum in the tetrahedral sheet, enhances its chemical reactivity, favoring the formation of new crystalline phases under mild hydrothermal conditions, and thus providing a definitive isolation of the radionuclides in the engineered barrier. Moreover, this synthetic clay has some features that allow its use as an optical sensor by doping with luminescent rare earth cations such as Eu3+. In this paper we discuss the local structure of the nanoclay Mica-4 using Eu3+ as a local probe to track the physical and chemical modifica-tions under hydrothermal conditions. For that purpose, a set of hydrothermal experiments has been carried out heating Mica-4 and an aqueous Eu(NO3)(3) solution in a stainless steel reactor at different temperatures and times. Optical properties of the as-treated samples were characterized by spectroscopic measurements. The fine peak structure of emission and the relative intensity of different Eu3+ transitions as well as the luminescence lifetime have been correlated with the structure and composition of this nanoclay, and the interaction mechanisms between the lanthanide ions and the clay mineral at different temperatures and times. Special attention has been paid to understanding the role of the aluminum content, which may act as either an aggregating or dispersing agent, in the optical features and reactivity of the system.
Noviembre, 2022 | DOI: 10.1016/j.jallcom.2022.166086
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