Improving Oxygen Transport in Perovskite-Type LaGaO₃ Solid Electrolyte through Strain

Lattice strain is a promising possibility to improve materials performance in view of their application in thin-film devices. In particular, defect and transport properties in ionic conductors may be tailored through strain effects, since defect formation energy and migration barriers are correlated to structural parameters which, in turn, are influenced by strain-induced deformations. In this computational study we predicted that oxide-ion diffusion in perovskite-type lanthanum gallate can be improved through application of tensile strain. The structural deformations required to accommodate tensile lattice strain in the perovskite system are shown to result in a preferential localization of the oxygen vacancies in the equatorial plane of the GaO₆ octahedra, while oxide-ion diffusion becomes anisotropic

Physicochemical Characterization of AlCl₃–1-Ethyl-3-methylimidazolium Chloride Ionic Liquid Electrolytes for Aluminum Rechargeable Batteries

Al-ion batteries technology is receiving growing attention thanks to the high natural abundance of aluminum and to the high energy density that can be obtained with a three-electron redox process. In this work, the physicochemical properties of the room temperature ionic liquid composed of aluminum chloride and 1-ethyl-3-methylimidazolium chloride ([EMIm]­Cl) were systematically investigated by varying the molar ratio AlCl₃/[EMIm]Cl in the range 1.1–1.7. The combined use of multinuclear (²⁷Al, ¹³C, ¹H) NMR, electrochemical impedance spectroscopy, and thermal analysis allowed us to shed light on the structure–properties relationships of this complex system, also resolving some controversial conclusions of previous literature. We showed that the 1.2 molar ratio is the best compromise between high ionic conductivity and the use of the highly toxic AlCl₃. This electrolyte was tested in a standard Al-ion cell and gave promising results even at very high current densities (<i>i</i> > 200 mA g^–1)

Ion Dynamics and Mechanical Properties of Sulfonated Polybenzimidazole Membranes for High-Temperature Proton Exchange Membrane Fuel Cells

Polybenzimidazole (PBI)-based membranes are one of the systems of choice for polymer electrolyte fuel cells. Monomer sulphonation is one of the strategies suggested to improve proton transport in these membranes. We report a NMR and dynamic mechanical study aiming to investigate the effect of the sulphonation on the proton dynamics and the mechanical properties of the membranes. The analyses of ¹H self-diffusion coefficients and ¹H and ³¹P spectra versus temperature show that sulphonation causes the formation of interchain cross-links, which involve phosphoric acid molecules and the sulfonic groups. This, in turn, reduces the proton mobility and, consequently, the ionic conductivity. The increase of the membrane stiffness with sulphonation is confirmed by dynamic mechanical analysis through the behavior of the storage modulus

Melilite LaSrGa_3−<i>x</i>Al_<i>x</i>O₇ Series: A Combined Solid-State NMR and Neutron Diffraction Study

Oxides characterized by a layered melilite structure, with general formula ABT¹₍₁₎T²₍₂₎O₇, find applications in many different technological fields due to their relevant magnetic, optical, and electrical properties. These functional properties are, in turn, related to local features such as structural defects and cation substitutions. Therefore, a complete structural characterization of these complex anisotropic compounds is mandatory, and the combined use of long-range (X-ray and neutron diffraction) and short-range (solid state NMR) techniques is a key approach to this aim. In this work, we present the full structural characterization of the series LaSrGa_3–<i>x</i>Al_<i>x</i>O₇ (<i>x</i> = 0, 1, 1.5, 2, and 3), which was obtained for the first time by means of a new sol–gel approach. Analysis of neutron diffraction data revealed that the distribution of La/Sr and Ga/Al on the respective sites is random. ²⁷Al and ⁷¹Ga solid state NMR enabled us to rationalize the local structure of the T sites in terms of nearest and next-nearest neighbors. This study provides a deep structural insight that can be helpful for the understanding of the functional properties and is a powerful strategy for the analysis of complex oxide systems

Covalent and Ionic Functionalization of HLN Layered Perovskite by Sonochemical Methods

We describe the functionalization of the layered perovskite HLaNb₂O₇ with <i>n</i>-propanol, <i>n</i>-decanol, 3-mercaptopropyl-trimethoxysilane, imidazole, <i>n</i>-decylamine, and histamine. The use of sonication is found to significantly improve the reaction yield and to reduce the reaction time, compared to conventional thermal treatment under reflux. The obtained intercalates are thoroughly characterized through the use of several complementary experimental techniques (scanning electron microscopy, IR spectroscopy, X-ray diffraction, thermogravimetric analysis, magic-angle spinning NMR), clarifying their structure and chemical bonding. The implications for the design of inorganic–organic composite materials are discussed

An Experimental and Theoretical Investigation of Loperamide Hydrochloride–Glutaric Acid Cocrystals

Cocrystallization is a powerful method to improve the physicochemical properties of drugs. Loperamide hydrochloride is a topical analgesic for the gastrointestinal tract showing low and pH-dependent solubility; for this reason, an enhancement of its solubility or dissolution rate, particularly at the pH of the intestinal tract, could improve its local efficacy. Here we prepared cocrystals of this active principle with glutaric acid and so obtained a new crystalline solid representing a viable alternative to improve the physicochemical properties and thus the pharmaceutical behavior of the drug. Differential scanning calorimetry, X-ray powder diffraction, Fourier infrared spectroscopy, solid-state NMR, and scanning electron microscopy coupled to the energy-dispersive X-ray spectrometry were used to investigate the new solid-phase formation. DFT calculations at B3LYP/6-31G­(d) level of theory, in the gas phase, including frequencies computation, provided a rationale for the interaction between loperamide hydrochloride and glutaric acid. The cocrystals showed improved water solubility in comparison with loperamide HCl, and the pharmaceutical formulation proposed was able to release the drug more rapidly in comparison with three reference commercial products when tested at neutral pH values