Determination of the Anisotropic Elastic Properties of Rocksalt Ge2Sb2Te5 by XRD, Residual Stress, and DFT

The chalcogenide material Ge2Sb2Te5 is the prototype phase-change material, with widespread applications for optical media and random access memory. However, the full set of its independent elastic properties has not yet been published. In this study, we determine the elastic constants of the rocksalt Ge2Sb2Te5, experimentally by X-ray diffraction (XRD) and residual stress and computationally…

Desarrollo de catalizadores soportados sobre estructuras porosas para aplicaciones de generación y combustión catalítica de hidrógeno en el contexto de energías renovables

El agotamiento de combustibles fósiles a corto y medio plazo y los cambios climáticos producidos por el efecto invernadero son algunas de las principales consecuencias del uso extendido de estos combustibles. En este escenario el hidrógeno como vector de transporte y almacenamiento de energía es un candidato muy atractivo en el contexto de un mayor…

Disorder-order phase transformation in a fluorite-related oxide thin film: In-situ X-ray diffraction and modelling of the residual stress effects

This work is focused on the transformation of the disordered fluorite cubic-F phase to the ordered cubic-C bixbyite phase, induced by isothermal annealing as a function of the residual stresses resulting from different concentrations of microstructural defects in the yttrium oxide, Y2O3.  This transformation was studied using in-situ X-ray diffraction and was modelled using Kolmogorov-Johnson-Mehl-Avrami…

Investigation of a Pt containing washcoat on SiC foam for hydrogen combustion applications

A commercial Pt based washcoat, used for catalytic methane combustion, was studied supported on a commercial SiC foam as catalytic material (Pt/SiC) for catalytic hydrogen combustion (CHC). Structural and chemical characterization was performed using Electron Microscopy, X-Ray Diffraction (XRD) and X-Ray Photoelectron Spectroscopy (XPS). The reaction was monitored following water concentration by Fourier Transform Infrared…

Atomic scale characterization of SiO2/4H-SiC interfaces in MOSFETs devices

The breakthrough of 4H-SiC MOSFETs is stemmed mainly due to the mobility degradation in their channel in spite of the good physical intrinsic material properties. Here, two different n-channel 4H-SiC MOSFETs are characterized in order to analyze the elemental composition at the SiC/SiO2 interface and its relationship to their electrical properties. Elemental distribution analyses performed by EELS…

Role of Y in the oxidation resistance of CrAlYN coatings

CrAlYN coatings with different aluminum (4–12 at.%) and yttrium (2–5 at.%) contents are deposited by d.c. reactive magnetron sputtering on silicon and M2 steel substrates using metallic targets and Ar/N2 mixtures. The influence of the nanostructure and chemical elemental distribution on the oxidation resistance after heating in air at 1000 °C is studied by means of cross-sectional scanning electron…

Full solution processed mesostructured optical resonators integrating colloidal semiconductor quantum dots

Herein we show a solution based synthetic pathway to obtain a resonant optical cavity with embedded colloidal semiconductor quantum dots (CSQDs). The optical cavity pore network, surrounded by two dense Bragg mirrors, was designed ad hoc to selectively host the quantum dots, while uncontrolled infiltration of those in the rest of the layered structure was prevented. Coupling…

Direct observation of doping incorporation pathways in self-catalytic GaMnAs

Doping mechanisms of Mn in GaAs nanowires (NWs) that have been grown self-catalytically at 600 °C by molecular beam epitaxy (MBE) are investigated using advanced electron microscopy techniques and atom probe tomography. Mn is found to be incorporated primarily in the form of non-magnetic tetragonal Ga0.82Mn0.18 nanocrystals in Ga catalyst droplets at the ends of the NWs, while trace amounts of Mn (22 ± 4 at. ppm) are also distributed randomly…

Removing the effects of the «dark matter» in tomography

Electron tomography (ET) using different imaging modes has been progressively consolidating its position as a key tool in materials science. The fidelity of a tomographic reconstruction, or tomogram, is affected by several experimental factors. Most often, an unrealistic cloud of intensity that does not correspond to a real material phase of the specimen («dark matter»)…

Island-type growth of Au–Pt heterodimers: direct visualization of misfit dislocations and strain-relief mechanisms

Structural and analytical characterization related to the formation mechanism of Au–Pt heterodimers from polyhedral Pt nanocrystals is reported. The observation of specific lattice strain effects and the emergence of misfit dislocations point to the relevance of the Stranski–Krastanov growth mode as a means of explaining the previously reported dimerisation reaction between Au and Pt. Two…