Dense Freeze‐cast Li_7La_3Zr_2O_(12) Solid Electrolytes with Oriented Open Porosity and Contiguous Ceramic Scaffold

Freeze casting is used for the first time to prepare solid electrolyte scaffolds with oriented porosity and dense ceramic walls made of Li_7La_3Zr_2O_(12) (LLZO), one of the most promising candidates for solid state battery electrolytes. Processing parameters ‐ such as solvent solidification rate, solvent type, and ceramic particle size ‐ are investigated, focusing on their influence on porosity and ceramic wall density. Dendrite‐like porosity is obtained when using cyclohexane and dioxane as solvents. Lamellar porosity is observed in aqueous slurries resulting in a structure with the highest apparent porosity and densest ceramic scaffold but weakest mechanical properties due to the lack of interlamellar support. The use of smaller LLZO particle size in the slurries resulted in lower porosity and denser ceramic walls. The intrinsic ionic conductivity of the oriented LLZ ceramic scaffold is unaffected by the freeze casting technique, providing a promising ceramic scaffold for polymer infill in view of designing new types of ceramic‐polymer composites

Dense Freeze‐cast Li_7La_3Zr_2O_(12) Solid Electrolytes with Oriented Open Porosity and Contiguous Ceramic Scaffold

Freeze casting is used for the first time to prepare solid electrolyte scaffolds with oriented porosity and dense ceramic walls made of Li_7La_3Zr_2O_(12) (LLZO), one of the most promising candidates for solid state battery electrolytes. Processing parameters ‐ such as solvent solidification rate, solvent type, and ceramic particle size ‐ are investigated, focusing on their influence on porosity and ceramic wall density. Dendrite‐like porosity is obtained when using cyclohexane and dioxane as solvents. Lamellar porosity is observed in aqueous slurries resulting in a structure with the highest apparent porosity and densest ceramic scaffold but weakest mechanical properties due to the lack of interlamellar support. The use of smaller LLZO particle size in the slurries resulted in lower porosity and denser ceramic walls. The intrinsic ionic conductivity of the oriented LLZ ceramic scaffold is unaffected by the freeze casting technique, providing a promising ceramic scaffold for polymer infill in view of designing new types of ceramic‐polymer composites

Material superconductor nanoestructurado tipo REBa2Cu3O7 (RE=Tierra Rara o Ytrio) con una elevada densidad de centros de anclaje de vórtices y su método de preparación

Solicitud de patente (concesión en curso).-- Referencia OEPM: P200603172.-- Fecha de presentación: 14/12/2006.-- Solicitantes: Consejo Superior de Investigaciones Científicas (CSIC).La presente invención se refiere a un material superconductor nanoestructurado tipo REBa2Cu3O7, donde RE= Tierra Rara o Ytrio, que comprende dos fases, una matriz principal de REBa2Cu3O7 y una fase secundaria de BaZrO3, CeO2, BaSnO3, BaCeO3, SrRuO3, La(1-x)MxMnO3 (M=Ca, Sr, Ba), RE2O3 y/o RE2Cu2O5. La fase secundaria se encuentra distribuida al azar en el seno de la matriz de forma que proporciona una alta densidad de defectos nanométricos en la estructura del material, aumentando la capacidad de anclar eficazmente los vórtices. Otro objeto de la invención es el procedimiento por el cual se obtienen estos materiales superconductores.Peer reviewe

Case-finding in primary care for coeliac disease: Accuracy and cost-effectiveness of a rapid point-of-care test

Background: An on-site, rapid, fingertip, whole-blood point-of-care test (POCT) is attractive for active case-finding of coeliac disease (CD) in primary care because of its simplicity. Aim: The aim of this article is to assess the usefulness and cost-effectiveness of adult case-finding using a POCT based on deamidated gliadin peptide antibodies (IgA/IgG-DGP) in primary care for CD diagnosis. Methods: A case-finding study for CD was conducted by using an easy-to-use, on-site, whole-blood for IgA/IgG-DGP-based fingertip POCT compared with tTG2 in 350 individuals. Sample size was calculated based on 0.28% prevalence in the reference population. Duodenal biopsies for histology, intraepithelial lymphocytes and in situ deposition of tTG2 were obtained if tTG2 and/or POCT were positive. Accuracy and cost-effectiveness of strategies using serology or POCT were calculated. Results: Prevalence of CD was 1.14% (95% CI, 0.3-3.4), almost double what was previously observed. Four patients were diagnosed with CD. tTG2 was positive in three (0.85%) and POCT in 29 (8.2%). Sensitivity of POCT for CD was 100%, specificity 93%, PPV 14%, and NPV 100%. POCT followed by duodenal biopsy was the most cost-effective approach in our setting (standard diagnosis: E13,033/case; POCT þ duodenal biopsy: E7360/case). Conclusions: A negative POCT allows ruling out CD in primary care, making it suitable for case-finding. POCT strategy was the most cost effective

Dual Substitution Strategy to Enhance Li+ Ionic Conductivity in Li7La3Zr2O12 Solid Electrolyte

Solid state electrolytes could address the current safety concerns of lithium-ion batteries as well as provide higher electrochemical stability and energy density. Among solid electrolyte contenders, garnet-structured Li7La3Zr2O12 appears as a particularly promising material owing to its wide electrochemical stability window; however, its ionic conductivity remains an order of magnitude below that of ubiquitous liquid electrolytes. Here, we present an innovative dual substitution strategy developed to enhance Li-ion mobility in garnet-structured solid electrolytes. A first dopant cation, Ga3+, is introduced on the Li sites to stabilize the fast-conducting cubic phase. Simultaneously, a second cation, Sc3+, is used to partially populate the Zr sites, which consequently increases the concentration of Li ions by charge compensation. This aliovalent dual substitution strategy allows fine-tuning of the number of charge carriers in the cubic Li7La3Zr2O12 according to the resulting stoichiometry, Li7–3x+yGaxLa3Zr2–yScyO12. The coexistence of Ga and Sc cations in the garnet structure is confirmed by a set of simulation and experimental techniques: DFT calculations, XRD, ICP, SEM, STEM, EDS, solid state NMR, and EIS. This thorough characterization highlights a particular cationic distribution in Li6.65Ga0.15La3Zr1.90Sc0.10O12, with preferential Ga3+ occupation of tetrahedral Li24d sites over the distorted octahedral Li96h sites. 7Li NMR reveals a heterogeneous distribution of Li charge carriers with distinct mobilities. This unique Li local structure has a beneficial effect on the transport properties of the garnet, enhancing the ionic conductivity and lowering the activation energy, with values of 1.8 × 10–3 S cm–1 at 300 K and 0.29 eV in the temperature range of 180 to 340 K, respectively