From chemical to structural order of electrodeposited Ni22P alloy: An XPS and EDXD study

Amorphous electrodeposited Ni-22 at.% P alloys were analyzed in the amorphous and re-crystd. state by EDXD and XPS surface anal. The re-crystn. kinetics were detd. following in situ structural changes by EDXD. Distinct diffraction patterns indicating the presence of Ni3P confirm alloy re-crystn. at 645. The XPS results show that all the core level binding energies of nickel such as Ni2p3/2 and Ni2p1/2 and phosphorus (P2p, P2s) remained const. after the change from x-ray amorphous to cryst. structure of the Ni-P alloy. Differences obsd. were as follows: (a) the binding energy difference between the Ni2p main lines and the satellite, (b) the fine structure of the NiLMM Auger lines, and (c) the d. of states in the valence band in the region of the Ni3d electrons. On the basis of these results from EDXD and XPS, the change in alloy structure from x-ray amorphous to cryst. influences the electronic structure of the Ni-P alloy but not the chem. state of phosphorus. An explanation based on the screening model proposed in the literature is discussed

Evidence of a rearrangement of the surface structure in titanium phthalocyanine sensors induced by the interaction with nitrogen oxides molecules

Thin-film samples of titanium phthalocyanine, a sensor of environmental pollutants, were studied by time resolved energy-dispersive x-ray reflectivity (EDXR). This original method demonstrated to be an ideal tool to follow the evolution of the films morphology upon gas exposure, in situ, also allowing an unexpected response of the sensors to be detected. Indeed, while the increase in thickness showed the characteristic feature of a "breathing-like" expansion, already observed in other metal-Pc, the curve of roughness versus exposure time exhibited a peak. This effect, in some cases evident by observation with the naked eye the EDXR data, was attributed to a surface structure rearrangement process

In situ space-resolved X-ray diffraction and time-resolved EDXD on efficient polymer-based photovoltaic devices: Microstructural properties and aging effects

Microstructural and morphological features of the layers forming integrated PTB7/PC71BM organic solar cells with Ca/Al cathode are studied. The effects of vacuum treatment on properties and durability were addressed using complementary approaches: time-resolved experiments revealing the structural evolution of the active layers under illumination were conducted combining the in situ energy dispersive X-ray diffraction (EDXD) technique with atomic force microscopy (AFM); space-resolved characterization of the integrated devices was possible via high resolution X-ray diffraction, using a nano-focused synchrotron radiation X-ray beam to discriminate the device components. Active layers surface morphology is stable under illumination and PC71BM structural properties remain unaltered. PTB7 undergoes crystallinity depletion, mainly at the active layer/cathode interface. This effect is actually inhibited in the device submitted to vacuum treatment, proving that this procedure induces stabilization at the cathode's buried interface, as verified by fourier transform infrared (FTIR) spectroscopy. Importantly, the protective role of the vacuum treatment results in a significant photovoltaic durability enhancement

Ferromagnetic Mn-doped Si0.3Ge0.7 nanodots self-assembled on Si(100)

Densely packed epitaxial Mn-doped Si0.3Ge0.7 nanodots self-assembled on Si(100) have been obtained. Their structural properties were studied using reflection high-energy electron diffraction, energy dispersive x-ray diffraction, atomic force microscopy, extended x-ray absorption fine structure measurements and high-resolution transmission electron microscopy. Mn5Ge1Si2 crystallites embedded in Si0.3Ge0.7 were found. They exhibit a ferromagnetic behaviour with a Curie temperature of about 225 K. RI FAVRE, Luc/B-3429-2010; Berbezier, Isabelle/E-7650-201