Coupling in situ synchrotron radiation with ex situ spectroscopy characterizations to study the formation of Ba1−xSrxTiO3 nanoparticles in supercritical fluids

High quality barium strontium titanate (BaxSr1 − xTiO3 with 0 ≤ x ≤ 1-BST) nanoparticles can be synthesized using supercritical fluids technology. Well crystallized particles of 20 nm with a narrow size distribution were produced in a single step. The reaction is achieved at relatively low temperature (T < 400 °C) and in tens of seconds. The combination of in situ synchrotron wide angle X-ray scattering (WAXS) and ex situ analyses in the form of Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and high resolution transmission electron microscopy (HR-TEM) leads to an understanding of the influence of the substitution of barium cations with strontium ones on the BST nanoparticle growth. A correlation between particle size, density of -OH groups at the surface of the particles and BST composition is exhibited; the higher the -OH density and the lower the strontium concentration, the larger the particles. This confirms that the formation of BST nanoparticles in supercritical fluids is governed by a sol-gel mechanism

Simple Setup Miniaturization with Multiple Benefits for Green Chemistry in Nanoparticle Synthesis

[Image: see text] The development of nanomaterials often relies on wet-chemical synthesis performed in reflux setups using round-bottom flasks. Here, an alternative approach to synthesize nanomaterials is presented that uses glass tubes designed for NMR analysis as reactors. This approach uses less solvent and energy, generates less waste, provides safer conditions, is less prone to contamination, and is compatible with high-throughput screening. The benefits of this approach are illustrated by an in breadth study with the synthesis of gold, iridium, osmium, and copper sulfide nanoparticles

A brief history of the social wage: Welfare before and after racial fordism

Successfully enabling a new battery technology, such as sodium-ion batteries, requires a thorough understanding of the functional properties of its building blocks. Knowing how the electrode materials behave upon operation is crucial to gain insight into how the battery technologies can be improved for optimal usage. Here we examine with X-ray total scattering and subsequent pair distribution function (PDF) analysis the structural response of hard carbon upon operation, which has been proposed as a possible electrode material for sodium ion batteries. PDF analysis reveals a clear correlation between the interplane and in-plane interatomic distances and the state of charge. The change in in-plane graphene behaviour corresponds to a reversible charge transfer between sodium and the antibonding orbitals in the upper π band of the graphene sheet, resulting in in-plane elongation and contraction upon cycling. As a result of the introduction of sodium into the structure upon discharge, the hard carbon structure is found to become increasingly disordered resulting in the initial structure not being able to fully recover upon desodiation. The more pronounced structural impact upon sodiation than seen in lithiated hard carbon suggests a larger electron transfer impact on the structure by influencing the π-orbitals of the neighboring, conjugated benzene rings. This means that the electron transfer cannot be described as a local electron transfer contribution as might be the case of lithium, but instead as a more delocalized contribution, in which the local structure of graphene experiences a larger change upon sodiation