Nature of Pd and Ti Metals in the Structure of CMAS Glass and Ceramics

The structure of electrically conductive CMAS‐TiO₂‐Pd glass and ceramics was investigated by transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), X‐ray photoelectron spectroscopy (XPS), X‐ray absorption near‐edge spectroscopy (XANES), and extended X‐ray absorption fine structure spectroscopy (EXAFS). The XANES spectra of Ti do not show any significant difference between the glasses ceramized in air or in a reducing “forming” gas, as well as between Pd‐containing versus Pd‐free samples, nor between surface versus bulk of the glass‐ceramic samples. However, EXAFS and XANES data recorded at the Pd K‐edge show significant dependences on whether the glass‐ceramic was ceramized in air or in “forming” gas. The XPS spectra of Ti 2p core‐level electrons for glasses ceramized in air or “forming” gas also show a strong difference depending on whether the samples did or did not contain Pd. STEM mapping confirms the existence of grains in the form of main crystalline phases identified with XRD, and also reveals the existence of Pd nanoparticles in glasses ceramized in both air and in “forming” gas.     

Synchrotron crystal and local structures,microstructure, and electrical characterization of Cu-doped LiFePO4/C via dissolution method with ironstone as Fe source

Journal of Materials Science: Materials in Electronics - Powders of lithium iron phosphate (LFP) with Cu doping and carbon coating were prepared by a dissolution method using Fe sourced from...     

Preparation of iron boride-silica core-shell nanoparticles with soft ferromagnetic properties

A one-pot aqueous chemical synthesis for silica-passivated ferromagnetic nanoparticles is presented. The average size of these particles is 84 ± 20?nm. The x-ray and electron diffraction experiments revealed that the nanoparticles are mainly composed of polycrystalline iron boride. The broad x-ray diffraction peak leads to an average crystallite size of 1.8?nm, which is much smaller than the overall size of the particles, and is consistent with the polycrystalline nature of the samples. M?ssbauer spectroscopy and magnetization experiments were used to establish the room temperature magnetic properties as well as the chemical nature of the particles. Fe(2)B dominates the composition of the nanoparticles, having a hyperfine field broadly distributed in the 10-33?T range. Alpha iron, the second ferromagnetic material identified in the particles, amounts to 4.6% of the composition. Finally, a paramagnetic phase accounting for approximately 14.6% of the material of the particles was also detected. These nanoparticles contain a core with soft ferromagnetic properties surrounded by a passivating silica layer, and are suitable for magnetically targeted drug delivery and electromagnetic induction heating applications.