1,721,011 research outputs found
Energy Dispersive X-ray Diffraction Applied to Laboratory Investigation on Proton Exchange Membrane Water Content in Working Fuel Cells
No full textAn original method, based on the energy-dispersive X-ray diffraction, has been recently proposed as a possible laboratory tool to accomplish long time resolved investigation of the water content in a Proton Exchange Membrane Fuel Cell.
However, this method has never been applied to a real working fuel cell. Therefore, a clear comprehension of its effectiveness in terms of relevant parameters such as time and space resolution, sensitivity and reproducibility has not yet been achieved. In this paper, all these aspects are discussed and clarified.
In order to focus on the method overall effectiveness and on the extent of possible improvements, a basic experimental configuration for both the electrochemical station and the X-ray equipment has been set.
The method is described with particular attention to its operating principle and to the evaluation of the errors introduced in data assessment. Finally, applications to some model experiments, in particular working states of the device, are provided and the obtained results are discussed
Una nuova tecnica per lo studio delle transizioni di fase mediante diffrazione a raggi-x a dispersione di energia. Applicazione alla cristallizazione da fuso del nylon12
No full textPolymer isothermal phase transition measurements by means of energy dispersive x-ray scattering
No full textStudy of the multiple melting in polymeric materials by EDXD-PT. DSC compared application to poly(ethylene-succinate)
No full textAn alternative method to DSC, for revealing the thermal dissolution of the phases coexisting in a polymeric sample, is using se structure-sensitive probe, like X-ray diffraction. The problem with this is that it would be necessary to collect many diffraction patterns and to process them using theoretically calculated quantities. Instead, we used a method we developed, which simplifies the experimental procedure in studying phase transitions. It is based on the energy dispersive X-ray Diffraction and results in a curve that represents the evolution of the system under heating. In this paper, we present for the first time a comparison between these two techniques applied to a sample of poly(ethylene-succinate) which shows a multiple melting behavior when subjected to heating. The ability of EDXD applied to phase transitions (PT) to reproduce the complex melting behavior of PES causes one to think that a new tool for these kind of studies, completely independent of DCS, has been found. The potentialities and the merits of EDXD-PT are discussed together with its possible future developments
Structural changes of electrodic materials in electrochemical cells observed by in situ energy dispersive X-ray diffraction (EDXD)
No full text
Energy dispersive x-ray diffraction and differential scanning calorimetry investigation of the melting behavior of poly(ethylene-succinate) crystallized at low undercooling
No full textThe behavior upon heating of poly(ethylene-succinate) samples crystallized at progressively lower undercooling has been studied. The multiple melting phenomena exhibited by this particular polymer subjected to a temperature ramp were investigated using both ordinary differential scanning calorimetry and an alternative technique, energy dispersive x-ray diffraction applied to phase transition. A critical comparison of the two methods adopted in the melting studies is included. Another application of the energy dispersive x-ray diffraction method, which enables one to distinguish the structural rearrangements that take place on different distance scales, is also described. (C) 2003 American Institute of Physics
Time-resolved morphological study of 'PEDOT:PSS' hole transporting layer for polymer solar cells
No full textThe reliability of the polymeric hole transport layer poly(3,4- ethylenedioxythiophene):poly(styrenesulphonate) (PEDOT:PSS), used in organic photovoltaic and single carrier diodes was addressed. The morphological properties of the blend were monitored during thermal treatments and under controlled humidity condition. The approach adopted, relying on joint use of in situ energy dispersive X-ray reflectivity (EDXR) and atomic force microscopy (AFM) techniques, allowed to observe, in real time, the occurrence of degradation phenomena related to both bulk and interface effects. Additionally, Fourier transform infrared (FTIR) spectroscopy experiments provided information on the chemical properties correlated to the blend morphological modifications. The overall approach allowed to identify aging process that may compromise the chemical-physical characteristics of the PEDOT:PSS hole conducting layer and, in turn, may have a relevant impact on the performances of the organic devices. © 2012 Elsevier B.V. All rights reserved
In situ studies of electrodic materials in Li-ion cells upon cycling performed by very-high-energy x-ray diffraction
No full textA very high-energy synchrotron radiation source (87 keV) was utilized for in situ sampling of the structural changes occurring in the electrodic materials of a Li-ion cell during charge-discharge cycling. The real-time evolution of their crystal lattice was obtained as a function of the degree of Li intercalation. As a result, new information on two electrodic materials, Li-Ti "zero strain" and Li-Ni-Co oxide, both of extreme interest for generation of rechargeable batteries, was gained. The actual change of the Li-Ti oxide lattice parameter upon cycling was observed in greater detail than before, and provided evidence of unexpected behavior in some intervals of the cycle. In the Li-Ni-Co sample, a new phase formed during the early stages of cycling that remained stable in the subsequent cycles was revealed. (C) 2001 American Institute of Physics
- …
