Octahedral conversion of a-SiO2-host matrix by pulsed ion implantation

This is the abstract. The results of measurements of X-ray photoelectron spectra (XPS) of a-SiO2-host material after pulsed implantation with [Mn+] and [Co+, Mn+]-ions as well as DFT-calculations are presented. The low-energy shift is found in XPS Si 2p and O 1s core-levels of single [Mn+] and dual [Co+, Mn+] pulsed ion-implanted a-SiO2 (E = 30 keV, D = 2*10^17 cm^-2) with respect to those of untreated a-SiO2.The similar changes are found in XPS Si 2p and O 1s of stishovite compared to those of quartz. This means that the pulsed ion-implantation induces the local high pressure effect which leads to an appearance of SiO6-structural units in alpha-SiO2 host, forming "stishovite-like" local atomic structure. This process can be described within electronic bonding transition from the four-fold "quartz-like" to six-fold "stishovite-like" high-pressure phase in SiO2 host-matrix. It is found that such octahedral conversion depends on the fluence and starts with doses higher than D = 3*10^16 cm^-2.Comment: 15 pages, 6 figures, 1 table, accepted in phys. stat. solidi (b

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Electron beam excitation in thin layered samples

International audienceEnergy transfer distributions dE/dx and respective excitation depth functions Φ of electron beams in heterogeneous layered samples are described by a successive Effective Layer method. This method is based on electron transmission rates through the top multilayer system replaced by an “effective layer” of the following bottom material. Thus energy depositions in heterogeneous layered metal samples (Al, Ag and Au) and dielectric insulating samples SiO2–Al2O3 are given. For the latter ones special energy-range relations R(E0) have been deduced for the common energy regions (1–30) keV of scanning electron microscopy (SEM). Application are given by cathodoluminescence depth profiling and electron beam charging of non-conductive samples