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Mingzhe Hu Yinglin Liu Haoshuang Gu Rong Yu Judith L. MacManus-Driscoll Adam P. Robinson 《Solid State Sciences》2009,11(7):1252-1257
The synthesis of large-scale one-dimensional silica nanotube (SNT) arrays embedded in Si substrate is demonstrated by using the combination of AAO template mask and Ar ion milling technique. The geometry of the SNTs could be precisely controlled by the process parameters, which included that the SNT diameter and the interpore distance were controlled by AAO anodization voltage and H3PO4 pore widening time, while the length of SNT was controlled by ion milling time and AAO aspect ratio. Also, the SNT fabrication parameters could be related to their photoluminescence (PL) emitting properties, when anodized at 40 V, pore widening in H3PO4 acid for 70 min and ion milled for 5 min, a strong intensity and stable ultraviolet (UV) light of 3.25 eV (381 nm) emitted from the SNTs under the excitation of 266 nm laser, which could be assumed arising from twofold coordinated silicon lone pair centers in the oxygen deficiency SNTs. The present fabrication of SNT arrays presents a novel method for intensity and frequency adjustable ultraviolet optoelectronic devices. 相似文献
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F. Song Å. Monsen Z.S. Li E.-M. Choi J.L. MacManus-Driscoll J. Xiong Q.X. Jia E. Wahlström J.W. Wells 《Surface science》2012,606(23-24):1771-1776
The surface and near-surface chemical composition of BiFe0.5Mn0.5O3 has been studied using a combination of low photon energy synchrotron photoemission spectroscopy, and a newly developed maximum entropy finite element model from which it is possible to extract the depth dependent chemical composition. In the uppermost few unit cells, an overabundance of Bi, and a deficiency of Fe and Mn are observed. In deeper layers, the measurements are consistent with bulk-like stoichiometry.Additionally, a definitive identification of all the observed species together with their abundance and depth dependence is given, and the mixed Fe and Mn valencies are estimated. In addition to the expected bulk valencies Mn3 + and Fe3 +, some Fe2 + and a small amount of Mn4 + are also observed. The maximum entropy finite element model demonstrated here is also discussed in more general terms and its potential application to the broader field of perovskite thin films is made apparent. 相似文献
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S.K. Chen X. Xu J.H. Kim S.X. Dou J.L. MacManus-Driscoll 《Physica C: Superconductivity and its Applications》2010,470(20):1211-1215
In this work, nano sized SiC powders were mixed with Mg and B and reacted by either a one-step insitu or two-step method resulted in different level of C substitution. X-ray diffraction shows the presence of Mg2Si signifying that the reaction between SiC and Mg occurred leading to the release of C in samples reacted in one-step method. Moreover, the much reduced value of a-axis indicates C substitution took place. Resistivity measurements showed higher intragrain scattering owing to a higher density of defects and/or impurities. These samples also show higher Hirr and Hc2 at 20 K in comparison to samples with mainly unreacted SiC (hence lower C substitution). More importantly, their Jc’s are more insensitive to high magnetic field (>4 T) at 6 K. However, at 20 K the effect of C content on Jc(H) is less pronounced. Finally, the order of magnitude of Jc(H) at both 6 K and 20 K is rather dominated by pinning. 相似文献
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