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Amorphous silicon nitride films deposited on Si(0 0 1) were irradiated with 540 keV C[60] ions to fluences ranging from 2.5 × 10[11] to 1 × 10[14] ions/cm2. The composition depth profiles of the irradiated samples were measured using high-resolution Rutherford backscattering spectroscopy. Both silicon and nitrogen in the film decrease rapidly with fluence. From the observed result the sputtering yields are obtained as 3900 ± 500 N atoms/ion and 1500 ± 1000 Si atoms/ion. Such large sputtering yield cannot be explained by either the elastic sputtering or the electronic sputtering, indicating that the synergy effect between the elastic sputtering and the electronic sputtering plays an important role.

Chain alignment can significantly influence the macroscopic properties of a polymeric material, but no general and versatile methodol. has yet been reported to obtain highly ordered cryst. packing of polymer chains, with high stability. Here, we disclose a strategy that relies on ordered crosslinks' to produce polymeric materials that exhibit a cryst. arrangement. Divinyl crosslinkers (2,5-divinyl-terephthalate) were first embedded, as substitutional ligands, into the structure of a porous coordination polymer (PCP), [Cu(terephthalate)triethylenediamine0.5]n. A representative vinyl monomer, styrene, was subsequently polymd. inside the channels of the host PCP. The polystyrene chains that form within the PCP channels also crosslink with the divinyl species. This bridges together the polymer chains of adjacent channels and ensures that, on selective removal of the PCP, the polymer chains remain aligned. Indeed, the resulting material exhibits long-range order and is stable to thermal and solvent treatments, as demonstrated by X-ray powder diffraction and transmission electron microscopy

Thin films of amorphous Si3N4 (thickness 20 nm) were irradiated with 120–720 keV C60+, 2+ ions and observed using transmission electron microscopy (TEM). The ion track produced in an amorphous material was directly observed by TEM. For quantitative analysis, the ion tracks were also observed using high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM). The observed ion track consists of a low density core (radius ∼2.5 nm) and a high density shell (width ∼2.5 nm), which is very similar to the ion tracks in amorphous SiO2 irradiated with high energy heavy ions observed by small angle X-ray scattering (SAXS). Although the observed ion tracks may be affected by surface effects, the present result indicates that TEM and HAADF-STEM have potential to observe directly the fine structures of ion tracks in amorphous materials.

Oxygen K-edge and Fe L2,3-edge electron energy-loss near-edge structures (ELNES) were measured for FeO6 octahedra and FeO4 tetrahedra in the brownmillerite Ca(Sr)FeO2.5 by focusing an electron probe at individual Fe sites using scanning transmission electron microscopy combined with electron energy-loss spectroscopy. The observed site-resolved oxygen K-ELNES showed different features reflecting the local chemical bonding around the FeO6 octahedra and FeO4 tetrahedra. A pre-peak in the O K-edge spectra, which is attributed to a transition to an unoccupied O 2p band hybridized with the Fe-3d band, shows splitting in the spectrum of the FeO6 octahedral site. Additionally, for the oxygen linking the octahedral and tetrahedral Fe sites in CaFeO2.5, charge transfer was found to preferentially occur toward the tetrahedral Fe ions. In the case of SrFeO2.5, charge transfer from the oxygen located in the ac plane was biased toward the tetrahedral Fe atoms. Based upon an analysis of the pre-peak intensity of the O K-ELNES, it was concluded that bonding between the oxygen and iron atoms at the tetrahedral site was more covalent in character than at the octahedral site. The strong covalent character of the tetrahedral sites would be one of the reasons for distortion in the FeO6 octahedra in Ca(Sr)FeO2.5, as exhibited by an extension along the b-axis.