Local Structure of Superionic Glass Ag x

To investigate relation between inhomogeneous structure of Agx(GeSe3)1-x superionic glass and conduction path formation, x-ray diffraction, neutron diffraction and EXAFS measurements on K-edges for each constituent were performed. Reverse Monte Carlo structural modelling based on these experimental data revealed that Ag conduction paths are formed in random glass media of GeSe4 tetrahedral network. The first sharp diffraction peak (FSDP) located at 1.1 Å-1 is mainly contributed by GeSe4 network, while an observed intense small angle scattering is contributed also by Ag-Ag as well as GeSe4 network

A Spectroscopic Study into Lanthanide Speciation in Deep Eutectic Solvents

Deep eutectic solvents are a new class of green solvents that are being explored as an alternative for used nuclear fuel and critical material recycling. However, there is a paucity of knowledge regarding metal behavior in them. This paper explores the underlying chemistry of rare-earth elements in choline chloride-based deep eutectic solvents by using a multi-technique spectroscopic methodology. Results show that speciation is highly dependent on the choice of the hydrogen-bond donor. Collected EXAFS data showed Ln3+ coordination with ethylene glycol and urea in their respective solvents and coordination with chloride in the lactic acid system. Generalized coordination environments were determined to be [LnL4???5], [LnL7???10], and [LnL5???6] in the ethylene glycol, urea, and lactic acid systems, respectively. Collected UV/vis spectra for Nd3+ and Er3+ showed variations with changing solvents, showing that Ln???Cl interactions do not dominate in these systems. Luminescence studies were consistent, showing varying emission spectra with varying solvent systems. The shortest luminescent lifetimes were observed in the choline chloride???ethylene glycol deep eutectic solvent, suggesting coordination through O???H groups. Combining all collected data allowed Eu3+ coordination geometries to be assigned

Highly Stable Iron- and Manganese-Based Cathodes for Long-Lasting Sodium Rechargeable Batteries

The development of long-lasting and low-cost rechargeable batteries lies at the heart of the success of large-scale energy storage systems for various applications. Here, we introduce Fe- and Mn-based Na rechargeable battery cathodes that can stably cycle more than 3000 times. The new cathode is based on the solid-solution phases of Na₄­Mn_<i>x</i>­Fe_3–<i>x</i>­(PO₄)₂­(P₂O₇) (<i>x</i> = 1 or 2) that we successfully synthesized for the first time. Electrochemical analysis and <i>ex situ</i> structural investigation reveal that the electrodes operate via a one-phase reaction upon charging and discharging with a remarkably low volume change of 2.1% for Na₄MnFe₂(PO₄)­(P₂O₇), which is one of the lowest values among Na battery cathodes reported thus far. With merits including an open framework structure and a small volume change, a stable cycle performance up to 3000 cycles can be achieved at 1C and room temperature, and almost 70% of the capacity at C/20 can be obtained at 20C. We believe that these materials are strong competitors for large-scale Na-ion battery cathodes based on their low costs, long-term cycle stability, and high energy density

Correlation between the green-like coloration and the structural and electronic properties of celadon glazes (I) Correlação entre a coloração esverdeada e as propriedades estruturais e eletrônicas de esmaltes celadon (I)

Celadon glazes have been investigated by means of ordinary X-ray fluorescence analysis, and X-ray diffraction and X-ray absorption spectra using synchrotron radiation. The tentative glazes are prepared by mixing raw celadon materials of Masuda feldspar, limestone, quartz, and extra-added Fe2O3 of about 1wt% at thermal treatment till about 1300 °C. It is found that the glaze-colors strongly depend on the Fe2O3 amount and the high-temperature treatment under oxidizing and deoxidizing in the used kiln. Especially, the characteristic color of blue-green, white-green-brown, and white-blue-green result from complex hybridized 3d5L and 3d6L bands. The 3d6L hybridization is induced by an electronic exchange interaction between an empty 3d6 orbital of Fe ions and an occupied 2p orbital of surrounding O ions in the (SiO2 - Al2O3 - CaO) basic complex ceramics of glass-state under the deoxidizing thermal treatment.<br>Esmaltes celadon foram investigados por meio de análise de fluorescência de raios X, e difração de raios X e espectros de absorção de raios X usando radiação síncrotron. Os esmaltes foram preparados por mistura de matérias-primas de celadon de feldspato Masuda, calcita, quartzo e 1 peso% a mais de Fe2O3 com tratamento térmico até 1300 °C. Foi verificado que as cores dos esmaltes dependem fortemente do teor de Fe2O3 e do tratamento térmico a alta temperatura sob atmosfera oxidante e desoxidante. As cores características verde azulada, marron esverdeada esbranquecida resultam das bandas de hibridização complexa 3d5L and 3d6L. A hibridização 3d6L é induzida por interação de troca eletrônica entre o orbital vazio 3d6 e íons Fe e um orbital 2p ocupado com íons oxigênio vizinhos nas cerâmicas complexas básicas (SiO2 - Al2O3 - CaO) no estado vítreo sob tratamento térmico desoxidante

On the oxidation state of &apos;Fe&apos; in LaFe1-xNixO3

The electrical and magnetic properties of rare earth orthoferrites are strongly dependent upon the electronic structure of Fe cations. This study investigates the electronic structure of Fe as a function of composition in LaFe1-xNixO3 using Fe K-edge X-ray absorption spectroscopy at room temperature. Analysis of the Fe K-edge X-ray absorption spectra indicates the presence of Fe3+ and Fe4+ in LaFe1-xNixO3. The concentration of F4+ increases with increasing Ni content in LaFe1-xNixO3. Variations in the oxidation state of Fe have been correlated to those in the electrical and magnetic characteristics of LaFe1-xNixO3. (C) 2014 Elsevier B.V. All rights reserved

Hydrated Manganese(II) Phosphate (Mn₃(PO₄)₂·3H₂O) as a Water Oxidation Catalyst

The development of a water oxidation catalyst has been a demanding challenge in realizing water splitting systems. The asymmetric geometry and flexible ligation of the biological Mn₄CaO₅ cluster are important properties for the function of photosystem II, and these properties can be applied to the design of new inorganic water oxidation catalysts. We identified a new crystal structure, Mn₃(PO₄)₂·3H₂O, that precipitates spontaneously in aqueous solution at room temperature and demonstrated its high catalytic performance under neutral conditions. The bulky phosphate polyhedron induces a less-ordered Mn geometry in Mn₃(PO₄)₂·3H₂O. Computational analysis indicated that the structural flexibility in Mn₃(PO₄)₂·3H₂O could stabilize the Jahn–Teller-distorted Mn­(III) and thus facilitate Mn­(II) oxidation. This study provides valuable insights into the interplay between atomic structure and catalytic activity