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Erbium-doped yttrium oxide nanotubes (Er 3+ :Y 2 O 3 NTs) with 0-100% doping levels were synthesized by a hydrothermal procedure followed by a dehydration process from Er 3+ :Y(OH) 3 NTs. The as-synthesized Er 3+ : Y 2 O 3 nanotubes ranged from 100 to 400 nm in outer diameter and 2 to 5 µm in length with a hexagonal cross section. A time-dependent nanostructure evolution study was performed under hydrothermal conditions, and the effects of other processing parameters, including pH, concentration, and ionic strength of the precursor solution as well as the time span for adding the alkaline solution, were found to dictate the purity and morphology of the as-synthesized Er 3+ :Y(OH) 3 nanostructures. A kinetics-controlled dissolution-recrystallization mechanism is proposed to explain the anisotropic growth of these hollow nanotubes from the hexagonal crystal structure of yttrium and erbium hydroxides. Outstanding room-temperature photoluminescence around 1535 nm was demonstrated for these Er 3+ :Y 2 O 3 NTs, making them promising for optical amplifier, laser, and active waveguide applications in telecommunications.

Measurements of the energy loss of fast electrons at an energy of 18 keV have been performed on molecules of hydrogen isotopes, gaseous T2 and frozen D2. Whereas in the case of gaseous T2 the values of total inelastic cross-section (σtot, gaseous = (3.40 ± 0.07) × 10 −18 cm 2 for E = 18.6 keV), average energy loss (εgaseous = (29.9 ± 1.0) eV) and peak position of the energy loss spectra (ε1, gaseous = 12.6 eV) agree well with the expectations, the corresponding values for quench condensed D2 differ significantly from the ones for gaseous T2. We observe a significant lower total inelastic cross-section (σ tot, solid = (2.98 ± 0.16) × 10 −18 cm 2 , for E = 18.6 keV) larger average energy loss (ε solid = (34.4 ± 3.0) eV) and higher peak position (ε 1, solid = (14.1 +0.7 −0.6 ) eV). These differences may be interpreted in terms of changes of the final state spectrum. A CI calculation for a D2 cluster shows indeed a clear shift of the excited states in agreement with the observation. PACS.34.80.Gs Molecular excitation and ionization by electron impact -78.90.+t Other topics in optical properties, condensed matter spectroscopy and other interactions of particles and radiation with condensed matter

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The nanostructure and photoluminescence of polycrystalline Er-doped Y2O3 thin films, deposited by radical-enhanced atomic layer deposition (ALD), were investigated in this study. The controlled distribution of erbium separated by layers of Y2O3, with erbium concentrations varied from 6to14at.%, was confirmed by elemental electron energy loss spectroscopy (EELS) mapping of Er M4 and M5. This unique feature is characteristic of the alternating radical-enhanced ALD of Y2O3 and Er2O3. The results are also consistent with the extended x-ray absorption fine structure (EXAFS) modeling of the Er distribution in the Y2O3 thin films, where the EXAFS data were best fitted to a layer-like structure. X-ray diffraction (XRD) and selected-area electron diffraction (SAED) patterns revealed a preferential film growth in the [111] direction, showing a lattice contraction with increasing Er doping concentration, likely due to Er3+ of a smaller ionic radius replacing the slightly larger Y3+. Room-temperature photoluminescence characteristic of the Er3+ intra-4f transition at 1.54μm was observed for the 500Å, 8at.% Er-doped Y2O3 thin film, showing various well-resolved Stark features due to different spectroscopic transitions from the I13∕24→I15∕24 energy manifold. The result indicates the proper substitution of Y3+ by Er3+ in the Y2O3 lattice, consistent with the EXAFS and XRD analyses. Thus, by using radical-enhanced ALD, a high concentration of optically active Er3+ ions can be incorporated in Y2O3 with controlled distribution at a low temperature, 350°C, making it possible to observe room-temperature photoluminescence for fairly thin films (∼500–900Å) without a high temperature annealing.

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We provide an outlook of some important state variables for emerging nanoelectronic devices. State variables are physical representations of information used to perform information processing via memory and logic functionality. Advances in material science, emerging nanodevices, nanostructures, and architectures have provided hope that alternative state variables based on new mechanisms, nanomaterials, and nanodevices may indeed be plausible. We review and analyze the computational advantages that alternate state variables may possibly attain with respect to maximizing computational performance via minimum energy dissipation, maximum operating switching speed, and maximum device density.

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