We compare three methods for quantitatively distinguishing the location of noble metal (NM) particles in mesopores from those found on the external support surface. MCM-41 and SBA-15 with NM located in mesopores or on the external surface were prepared and characterized by TEM. 31 P MAS NMR spectroscopy was used to quantify arylphosphines in complexes with NM. Phosphine/NM ratios drop from 2.0 to 0.2 when increasing the probe diameter from 1.08 to 1.54 nm. The reaction between NM and triphenylphosphine (TPP) within 3.0 nm MCM-41 pores takes due to confinement effects multiple weeks. In contrast, external NM react with TPP instantly. A promising method is filling the pores by using the pore volume impregnation technique with tetraethylorthosilicate (TEOS). TPP loading revealed that 66 % of NMs are located on the external surface of MCM-41. The pore filling method can be used in association with any probe molecule, also for the quantification of acid sites.

Atom Probe Tomography (APT) is currently a well-established technique to analyse the composition of solid materials including metals, semiconductors and ceramics with up to near-atomic resolution. Using an aqueous glucose solution, we now extended the technique to frozen solutions. While the mass signals of the common glucose fragments CxHy and CxOyHz overlap with (H2O)nH from water, we achieved stoichiometrically correct values via signal deconvolution. Density functional theory (DFT) calculations were performed to investigate the stability of the detected pyranose fragments. This paper demonstrates APT’s capabilities to achieve sub-nanometre resolution in tracing whole glucose molecules in a frozen solution by using cryogenic workflows. We use a solution of defined concentration to investigate the chemical resolution capabilities as a step toward the measurement of biological molecules. Due to the evaporation of nearly intact glucose molecules, their position within the measured 3D volume of the solution can be determined with sub-nanometre resolution. Our analyses take analytical techniques to a new level, since chemical characterization methods for cryogenically-frozen solutions or biological materials are limited.

a change in its optical constants during lithiation. However, a quantification of the optical properties and their tailoring via dis/charging has not been probed yet.The present study aims at the quantification of the optical constants, that is, the complex refractive index (CRI) and its change during intercalation by varying the lithium content of Li x Mn 2 O 4 from x = 0 to x = 1. Furthermore, an attempt is made to establish a link between this change in optical constants to the band structure of the material, learned from various sources. [11,15,[18][19][20][21] Similar characteristics have been reported for other electrochromic materials, such as Nb 2 O 5 , WO 3 , V 2 O 5 , and MoO 3, [22] which are known to change their optical properties, namely the real (n) and imaginary (k, or extinction coefficient) part of the CRI during an electrochemical reaction. In these materials, intercalation of charged species results in the generation of different electronic absorption bands in the optical spectrum or insertion of additional bound charges acting as harmonic oscillators. [22] For the present study, the reflection spectrum is measured at different stages of intercalation to clarify such electrochromic phenomenon. The measured spectra are evaluated to extract the CRI of the material for different lithium contents. Furthermore, an innovative method of recording the reflectance spectrum in situ during the electrochemical reaction is demonstrated (Figure 1c) that provides an additional time resolution to the spectrometry. Results Structural CharacterizationThe X-ray diffractogram (XRD) spectra of representative samples of LMO in the as-deposited and annealed states are shown in Figure 2a. No characteristic LMO diffraction peaks are observed for the as-deposited layer (bottom curve of Figure 2a). Only a small hump, observed at 61.98° (marked with *), could be due to the LMO structure corresponding to {440} planes. This reflection is very broad and shifted in comparison to the work of Wickhamt and Croft. [23] (JCP2 database) that predicts the position at 63.78°. The shape and the shift in the reflection suggest that the LMO layer is nanocrystalline and stressed, as it is usually the case for sputter-deposited layers.The optical response of lithium manganese oxide (LiMn 2 O 4 , LMO) on intercalation with Li ions is quantitatively characterized. For this purpose, a layer of LMO and a layer of platinum, acting as current collector/reflector, are deposited on oxidized silicon wafers. The active layer is structurally characterized using X-ray diffractogram and transmission electron microscopy. Well-defined intercalation states are prepared electrochemically and investigated by optical spectrometry in reflectance geometry. The measured dispersion curves are described by the Clausius-Mossotti dispersion equation to derive the complex refractive index as a function of wavelength and intercalation state. The observed variation of the effective resonant wavelength is consistent with the change in the band structure of LMO with l...

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Metal additive manufacturing of dental prostheses consisting of cobalt−chromium−tungsten (Co−Cr−W) alloys poses an alternative to investment casting. However, metal additive manufacturing processes like Laser Powder‐Bed Fusion (LPBF) can impact the elastic constants and the mechanical anisotropy of the resulting material. To investigate the phase compositions of mechanically different specimens in dependence of their postprocessing steps (e. g. heat treatment to relieve stress), the current study uses X‐ray Diffraction (XRD), Electron BackScatter Diffraction (EBSD), and Transmission Electron Microscopy (TEM) for phase identification. Our studies connect plastic deformation of Remanium star CL alloy with the formation of the hexagonal ϵ‐phase and heat treatment with the formation of the D024‐phase, while partially explaining previously observed differences in Young's moduli.

the material was first explored by Murphy et al. in 1983, [3] but only in 1995 Ohzuku et al. demonstrated its use in lithium-ion battery application and reported a nearly constant dis-/charge voltage of 1.55 V versus Li/Li + . [4] The constant voltage for de-/intercalation is indicative of a phase transformation during lithium insertion/ removal. However, the existence of a twophase reaction at room temperature and on a macroscopic scale has been debated in the past, with reports suggesting solidsolution [5] and/or nano-domains [6] in an equilibrium condition. Nevertheless, the existence of the two phases was confirmed by direct imaging individual phases using high-resolution transmission electron microscopy (TEM). [7] A cubic unit-cell of Li 4/3 Ti 5/3 O 4 has 8 formula units with 32 oxygen atoms located at the 32e sites, 1/3rd of the lithium and all of the titanium atoms are occupying 16d sites (octahedral positions) and the remaining 8 atoms of lithium are at 8a sites (tetrahedral positions). [8] During the phase transformation to Li 7/3 Ti 5/3 O 4 upon lithium insertion, the atoms of lithium at the 8a sites shift to the neighboring 16c position (octahedral position) and the insertion of eight additional lithium atoms takes place in the remaining 16c positions thus filling up all of the octahedral sites. [4,8] This reordering and insertion of lithium atoms, is accompanied by a huge change in the electronic [8] and the optical properties. [9] However, structurally, there is a mere 0.2% change in the volume of the unit-cell (hence the term "zero-strain" phase transformation was coined). [4] The fast dis-/charge ability of LTO (practically achieved by surface modification and reducing particle size) [2] must be governed by the transport properties of lithium and the kinetics of phase propagation in the electrode, provided, the electronic conductivity is sufficient. Ganapathy et al., [16] using first-principle calculations, addressed the migration across the phase boundary and its movement during the phase transformation to explain the fast dis-/charging ability of this material. Their calculation suggests that a fast migration in and out of the phase boundary enables the phase boundary to move almost like a "liquid." This would be in contrast to some silicon-based [10][11][12] and hydrogen-based systems [13,14] where the interface between structurally different phases is known to hinder the migration of atoms. Such hindrance at the phase boundary would lead to a deviation from a normal diffusion-controlled parabolic growth to a slower interface-controlled linear growth of the silicide or hydride phase in the initial stages of atomic transport. This study is aimed at experimentally determining the migration of Lithium titanate is one of the most promising anode materials for high-power demands but such applications desire a complete understanding of the kinetics of lithium transport. The poor diffusivity of lithium in the completely lithiated and delithiated (pseudo spinel) phases challenges to explain the highr...

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