Kurobori, T.; Hirose, Y.; Kawamura, K.; Hirano, M.; Hosono, H.
doi: 10.1002/pssc.200490028pmid: N/A
The cover picture of this issue of physica status solidi (c) has been taken from the article [1].
Skuja, L.; Hirano, M.; Hosono, H.; Kajihara, K.
doi: 10.1002/pssc.200460102pmid: N/A
An insight into the present understanding of point defects in the simplest and the most radiation‐resistant oxide glass, glassy silicon dioxide (silica) is presented. The defects and their generation processes in glassy and α‐quartz forms of silicon dioxide are significantly different. The only defect, confirmed to be similar in both materials, is oxygen vacancy. In silica, additional defects of dangling bond type are generated from precursor sites formed by strained Si‐O bonds, and by modifier ions. The optical absorption spectra of silica are dominated by paramagnetic dangling bond type defects: silicon dangling bond (“E′‐center”) and oxygen dangling bond (“non‐bridging oxygen hole center, NBOHC”). Radiation‐induced interstitial oxygen atoms exist in peroxy linkage (Si‐O‐O‐Si) form, they can react with oxygen dangling bonds to create peroxy radicals or dimerize into interstitial O2 molecules. Hydrogen doping helps to reduce the defect concentration, however, creates new precursors in the form of hydroxyl groups and may stimulate O vacancy generation. Doping by fluorine reduces the number of strained Si‐O bonds and results in glass, which has higher vacuum ultraviolet transparency and higher resistance to excimer laser light than pure silica. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
doi: 10.1002/pssc.200460104pmid: N/A
Wide‐gap materials, and especially defects and dopants in them, have characteristics that could enable quantum information processing. Spectroscopy, in particular, is a powerful resource, and spectroscopic methods might be used to manipulate quantum information. In some cases, the methods might lead to optically‐controlled spintronics and, conceivably, to quantum information processing at room temperature. Other classes of device, whilst of more limited value technologically, do illustrate the pervasive role of quantum physics that is sometimes overlooked. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
doi: 10.1002/pssc.200460105pmid: N/A
We overview definitions, properties and applications of Carbon nanotubes (CNTs). We describe the CNTs lifecycle: starting with phases and requirements, going through the different synthesis methods, describing then the various purification techniques. The fundamentals of functionalization and the use of defects in CNTs are reviewed, in connection also to ion irradiation techniques. Metal oxides and other semiconducting 1D nanostructures are then considered, before entering the description of the main features of the present status of INFN‐LNF research in nanoscience, focusing on CNTs, as well as on aluminium nitride NTs (AlN NTs). We conclude our review by illustrating device application criteria for many applications in different areas of the field of nanotechnology. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Jia, W.; Zhou, Y.; Keszler, D. A.; Jeong, Joa‐Young; Jang, K.W.; Meltzer, R.S.
doi: 10.1002/pssc.200460108pmid: N/A
Large band‐gap materials doped with rare earth‐ions are currently of great interest as new vacuum UV phosphors for lighting and displays. In this report, the optical properties of YPO4 and YBO3 doped with Pr, Tm, Er, and Eu are described. The emission resulting from the VUV excitation of the parity allowed 4fn–15d1 states and their quantum efficiencies are reported. Relaxation between the 4fn–15d1 and nearby 4fn excited states is observed for some of these ions, and the dynamics of these excited states is reported. In doubly‐doped samples, the prospects for quantum cutting by using cross relaxation energy transfer in which some of the energy of the initially excited 4fn–15d1 state is transferred to an acceptor ion so that both donor and acceptor ions are left in an excited state from which they each can emit a photon are examined. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Kawabata, S.; Kitaura, M.; Nakagawa, H.
doi: 10.1002/pssc.200460109pmid: N/A
The emission spectrum of CdCl2 is composed of ultraviolet (UV) and yellow (Y) bands peaking at 3.70 and 2.30 eV, respectively. In order to determine the initial states of the Y‐luminescence, decay curves of the Y‐emission were measured at 8K by varying emission energy in the range from 1.64 eV to 3.13 eV. The observed decay curves are composed of two or three exponential components. The values of lifetime for them were 900, 460 and 60 µs. The emission spectrum for each decay component, i.e., life‐time resolved emission spectrum, was analyzed by the observed decay curves. The emission spectrum for the component of 460 µs lifetime exhibits a dominant band at 2.30 eV and a satellite band at 3.03 eV. The emission spectrum for the component of 60 µs lifetime is reproduced by the three Gaussian bands peaking at 2.21, 2.65 and 2.87 eV. For the component of 900 µs lifetime, only a single band appears at 1.73 eV. The origin of the emission bands in life‐time resolved emission spectra is briefly discussed, and the initial states of Y‐luminescence are explained by the excited states of a [Cd2+Cl–6] 4– complex molecular ion. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ghica, D.; Nistor, S. V.; Vrielinck, H.; Callens, F.; Goovaerts, E.; Schoemaker, D.
doi: 10.1002/pssc.200460110pmid: N/A
A new electron trapped Fe+‐type centre produced in SrCl2:Fe single crystals grown in chlorine atmosphere and X‐ray irradiated at 80 K has been analysed using Electron Paramagnetic Resonance (EPR). The Fe+(IIa) centre (S = 1/2) exhibits monoclinic local symmetry with the two g‐tensor principal axes in a {110} plane being slightly tilted away from <001> and <1–10>. The EPR parameters have been determined and discussed in correlation with those of the tetragonal Fe+(II) paramagnetic centre. The Fe+(IIa) centre seems to consist of a fourfold coordinated Fe+ ion slightly perturbed by a neighbouring defect. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Kotlov, A.; Dolgov, S.; Feldbach, E.; Jönsson, L.; Kirm, M.; Lushchik, A.; Nagirnyi, V.; Svensson, G.; Zadneprovski, B.I.
doi: 10.1002/pssc.200460111pmid: N/A
For the first time the characteristics of the main emission of Al2(WO4)3 are reported. In order to distinguish the excitonic and electron‐hole processes in Al2(WO4)3 we measured the creation spectrum of photostimulated luminescence under irradiation by synchrotron light and compared it to the excitation spectrum of the main emission. It is shown that the onset of the excitation spectrum of the main 2.7 eV emission of Al2(WO4)3 is at 5 eV, while the threshold of the creation of electron‐hole pairs is measured to be 8.7 to 9.5 eV at 8 K. The latter value is in good agreement with the band‐gap value of α‐Al2O3 (9.4 eV). This supports the suggestion that free electrons and holes are created in tungstates due to electronic transitions from oxygen to cation states situated several eV above the bottom of the conduction band. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spassky, D.; Ivanov, S.; Kitaeva, I.; Kolobanov, V.; Mikhailin, V.; Ivleva, L.; Voronina, I.
doi: 10.1002/pssc.200460112pmid: N/A
The luminescent and reflectivity spectra of a series of the molybdates with the scheelite crystal structure were investigated using synchrotron radiation. The main features in reflectivity spectra in the energy range of 3.2–40 eV were analyzed. The luminescence spectra were measured under X‐ray excitation and their relative intensities were explained in the frames of the configuration curves model. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
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