Amorphous transition metal oxides are recognized as leading candidates for electrochromic window coatings that can dynamically modulate solar irradiation and improve building energy efficiency. However, their thin films are normally prepared by energy-intensive sputtering techniques or high-temperature solution methods, which increase manufacturing cost and complexity. Here, we report on a room-temperature solution process to fabricate electrochromic films of niobium oxide glass (NbO) and 'nanocrystal-in-glass' composites (that is, tin-doped indium oxide (ITO) nanocrystals embedded in NbO glass) via acid-catalysed condensation of polyniobate clusters. A combination of X-ray scattering and spectroscopic characterization with complementary simulations reveals that this strategy leads to a unique one-dimensional chain-like NbO structure, which significantly enhances the electrochromic performance, compared to a typical three-dimensional NbO network obtained from conventional high-temperature thermal processing. In addition, we show how self-assembled ITO-in-NbO composite films can be successfully integrated into high-performance flexible electrochromic devices.

Quantitative analysis of the X-ray pair distribution function collected on calcium silicate hydrates having Ca/Si ratios ranging between 0.57 and 1.47 was applied. With increasing Ca/Si ratio, Si bridging tetrahedra are omitted and Ca(OH)2 is detected at the highest ratios.

were synthesized from α-Li 2 IrO 3 and Li 2 RuO 3 respectively by ion exchange in an AgNO 3 melt. The crystal structures of the title compounds were solved from high resolution laboratory X-ray powder diffraction (XRPD) patterns and from pair distribution function (PDF) analysis using synchrotron X-ray powder diffraction data. In both crystal structures edge sharing LiO 6/3and (Ir/Ru)O 6/3 -octahedra form honeycomb like layers that are stacked in a staggered fashion. Silver cations, situated in-between the layers mediate the interlayer interactions by linear O-Ag-O bonds.Anisotropic peak broadening in the XRPD patterns and diffuse scattering occurring as streaks in the precession electron diffraction (PED) patterns indicate the presence of stacking faults, which could be also visualized by high resolution transmission electron microscopy (HRTEM). Possible alternative stacking sequences were derived from the ideal crystal and incorporated into a microstructure model. By applying a supercell approach that randomly generates and averages stacking sequences based on transition probabilities and combining it with a grid search algorithm, the microstructures, i.e. the degrees of faulting in the structures of the title compounds were refined to the measured XRPD data. In result the crystal structures of Ag 3 LiIr 2 O 6 and Ag 3 LiRu 2 O 6 were found to be vastly faulted with almost no coherence of the stacked layers. † Electronic supplementary information (ESI) available. CCDC 1912803 and 1912804. For ESI and crystallographic data in CIF or other electronic format see

International audienceWe have investigated the amorphization of β-trehalose by high energy milling using in situ and ex situ synchrotron powder diffraction and PDF analysis. From this analysis we show that amorphization takes place through a two-phase process involving an amorphous and a long-range ordered phase. The proportion and coherent domain size of the latter rapidly decrease with milling time until the whole sample appears amorphized. The PDF describing the local structure of the amorphous phase after two hours of milling is very close to that of a sample quenched from the liquid, and seems to continue to evolve for longer milling times. Their differences with the PDF expected for a rigid THL molecule confirm the existence of a conformational disorder of the torsion angles from the glycosidic linkage between the two cycles forming the molecule

BackgroundVernadite is a nanocrystalline and turbostratic phyllomanganate which is ubiquitous in the environment. Its layers are built of (MnO6)8− octahedra connected through their edges and frequently contain vacancies and  (or) isomorphic substitutions. Both create a layer charge deficit that can exceed 1 valence unit per layer octahedron and thus induces a strong chemical reactivity. In addition, vernadite has a high affinity for many trace elements (e.g., Co, Ni, and Zn) and possesses a redox potential that allows for the oxidation of redox-sensitive elements (e.g., As, Cr, Tl). As a result, vernadite acts as a sink for many trace metal elements. In the environment, vernadite is often found associated with tectomanganates (e.g., todorokite and cryptomelane) of which it is thought to be the precursor. The transformation mechanism is not yet fully understood however and the fate of metals initially contained in vernadite structure during this transformation is still debated. In the present work, the transformation of synthetic vernadite (δ-MnO2) to synthetic cryptomelane under conditions analogous to those prevailing in soils (dry state, room temperature and ambient pressure, in the dark) and over a time scale of ~10 years was monitored using high-energy X-ray scattering (with both Bragg-rod and pair distribution function formalisms) and transmission electron microscopy.ResultsMigration of Mn3+ from layer to interlayer to release strains and their subsequent sorption above newly formed vacancy in a triple-corner sharing configuration initiate the reaction. Reaction proceeds with preferential growth to form needle-like crystals that subsequently aggregate. Finally, the resulting lath-shaped crystals stack, with n × 120° (n = 1 or 2) rotations between crystals. Resulting cryptomelane crystal sizes are ~50–150 nm in the ab plane and ~10–50 nm along c*, that is a tenfold increase compared to fresh samples.ConclusionThe presently observed transformation mechanism is analogous to that observed in other studies that used higher temperatures and (or) pressure, and resulting tectomanganate crystals have a number of morphological characteristics similar to natural ones. This pleads for the relevance of the proposed mechanism to environmental conditions.Electronic supplementary materialThe online version of this article (doi:10.1186/s12932-015-0028-y) contains supplementary material, which is available to authorized users.