V. Rossi Albertini

In situ energy dispersive x-ray reflectometry measurements on organic solar cells upon working

The change in the morphology of plastic solar cells was studied by means of time-resolved energy dispersive x-ray reflectivity (XRR). This unconventional application of the XRR technique allowed the follow up of in situ morphological evolution of an organic photovoltaic device upon working. The study consisted of three steps: A preliminary set of XRR measurements on various samples representing the intermediate stages of cell construction, which provided accurate data regarding the electronic densities of the different layers; the verification of the morphological stability of the device under ambient condition; a real-time collection of XRR patterns, both in the dark and during 15h in artificial light conditions which allowed the changes in the system morphology at the electrode-active layer interface to be monitored. In this way, a progressive thickening of this interface, responsible for a reduction in the performances of the device, was observed directly.

In situ studies of electrodic materials in Li-ion cells upon cycling performed by very-high-energy x-ray diffraction

A 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.

The SPARC project: a high-brightness electron beam source at LNF to drive a SASE-FEL experiment

Abstract The Project Sorgente Pulsata e Amplificata di Radiazione Coerente (SPARC), proposed by a collaboration among ENEA–INFN–CNR–Universita’ di Tor Vergata–INFM–ST, was recently approved by the Italian Government and will be built at LNF. The aim of the project is to promote an R&D activity oriented to the development of a coherent ultra-brilliant X-ray source in Italy. This collaboration has identified a program founded on two main issues: the generation of ultra-high peak brightness electron beams and of resonant higher harmonics in the SASE-FEL process, as presented in this paper.

Refined, in-situ EDXD structural analysis of the Li[Li1/3Ti5/3]O4 electrode under lithium insertion–extraction

An in-situ energy dispersive X-ray diffraction (EDXD) analysis has been run on the Li[Li1/3Ti5/3]O4 compound upon Li intercalation–deintercalation process. The results confirm that this process is accompanied by a very small variation of the host lattice parameter, i.e., confined between 1‰ over the entire cycle. This value, which agrees with previous literature information, concurs to demonstrate that Li[Li1/3Ti5/3]O4 may indeed be considered as a zero-strain intercalation compound, this being a characteristic of key technological importance since lattice strains upon cycling are among the main causes of capacity decays in lithium battery electrodes. In addition, this work confirms that EDXD is a quite convenient technique for electrochemical measurements since, allowing in-situ lattice parameter determinations, may lead to a complete evaluation of the intermediate stages of the intercalation process and, possibly, to detect differences among the various cycles.

Spatially‐Resolved In‐Situ Structural Study of Organic Electronic Devices with Nanoscale Resolution: The Plasmonic Photovoltaic Case Study

A novel high spatial resolution synchrotron X-ray diffraction stratigraphy technique has been applied in-situ to an integrated plasmonic nanoparticle-based organic photovoltaic device. This original approach allows for the disclosure of structure-property relations linking large scale organic devices to length scales of local nano/hetero structures and interfaces between the different components.

A new technique for the study of phase transitions by means of energy dispersive x-ray diffraction. Application to polymeric samples

A new application of energy dispersive x-ray diffraction to the kinetics of phase transitions is reported. The aim of this work is to provide a new investigation tool to follow the evolution of polymeric systems from the initial to the final phase. The theoretical treatment is developed both for constant density transitions and for the variable density ones. The experimental route is illustrated by an example.

Time-resolved energy dispersive x-ray reflectometry measurements on ruthenium phthalocyanine gas sensing films

The energy dispersive (ED) variant of the conventional x-ray reflectivity (XR) provides an atomic scale determination of the morphological characteristics of thin films, such as their thickness and surface roughness. We report on the in situ EDXR measurements of the (minimal) morphological changes of ruthenium phthalocyanine gas sensing thin films. A series of reflectivity spectra have been collected, during the exposure of the films to a gas flux of nitrogen oxides (NOx) molecules. The measurements allowed a very high density time sampling of the evolution of the two morphological parameters, providing important information on the gas-film interaction.

Energy dispersive X-ray diffraction study of phase development during hardening of calcium phosphate bone cements with addition of chitosan.

The aim of this work was to study the phase transformation during the setting reaction of two calcium phosphate bone cements based on either alpha tricalcium phosphate (alpha-TCP) or tetracalcium phosphate (TetCP) initial solid phase, and a magnesium carbonate-phosphoric acid solution as the hardening liquid. Low molecular weight (38.2 kDa) chitosan was used to retard the cements setting reaction. To follow the kinetics of the phase development, an energy dispersive X-ray diffraction technique was applied. This technique allowed the collection of diffraction patterns from the cement pastes in situ starting from 1 min of the setting process. In the case of the TetCP-based cement, the appearance and evolution of an intermediate phase was detected.

Thermal, electrochemical and structural properties of stabilized LiNiyCo1−y−zMzO2 lithium-ion cathode material prepared by a chemical route

Layered compounds, such as LiNiO2 and LiCoO2 , have been extensively studied as active cathodic materials in lithium-ion batteries. Mixed oxides having general formula LiNiyCo1−yO2 represent a good compromise between the limited cyclability of LiNiO2 and the high cost of LiCoO2. However, recent studies have demonstrated that LiNiyCo1−yO2 compounds are thermally unstable in their charged state, undergoing exothermic reactions that might cause thermal runaway and safety concern. The stability of the compounds may be greatly controlled by doping with a suitable metal, M = Al, Mg. In this work we further investigate the role of the doping metal on the thermal, electrochemical and structural characteristics of the LiNiyCo1−y−zMzO2 electrode materials. These materials were prepared using a soft chemistry route, to achieve the proper control of the chemical homogeneity and of the microstructural properties of the final samples. The thermal behavior of the doped LiNiyCo1−y−zMzO2, where M = Al, was studied using differential scanning calorimetry. The structural properties upon cycling were investigated by a recently, in-house developed, in situ energy dispersive X-ray diffraction (EDXD) technique. The reversibility and rate capabilities of the cathodes in lithium cells were characterized using electrochemical equipment.

Experimental evidence of a two-step reversible absorption/desorption process in ruthenium phtalocyanine gas sensing films by in situ energy dispersive x-ray reflectometry

An in situ energy dispersive x-ray reflectivity technique was used to study the morphological changes of gas sensing thin films of ruthenium phtalocyanine (RuPc)2 induced by gas absorption/desorption processes. The time-resolved collection of reflectivity spectra during the exposure of each film to a gas flux of nitrogen oxides provided the evolution of the morphological parameters (thickness and roughness). The gas absorption process develops in two stages: The first induces morphological changes characteristic of a surface (adsorption) process, while the second is dominated by a bulk effect. This two-step behavior is also observed in the desorption process: When the thermal treatment is performed at 130°C, the gas is released from the bulk only. Conversely, at higher temperatures, the gas is fully released, i.e., also from the surface, and the initial film thickness is regained. Finally, a further in situ study upon a second absorption treatment was carried out: In this case, only the film bulk diffusio...