Papers by Keyword: Cathodoluminescence

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Authors: V.A. Skuratov, S.M. Abu-Al Azm, V.A. Altynov
Authors: C. Trager-Cowan, A.M. Paterson, R.W. Martin, K.P. O'Donnell, J.T. Mullins, G. Horsburgh, K.A. Prior, B.C. Cavenett
Authors: J.H. Edgar, L.H. Robins, S.E. Coatney, L. Liu, J. Chaudhuri, K. Ignatiev, Z. Rek
Authors: Jue Zhong, Peter Mascher, Werner Puff, A.H. Kitai
Authors: Alexander A. Lebedev, Maria V. Zamoryanskaya, Sergey Yu. Davydov, Demid A. Kirilenko, Sergey P. Lebedev, Lev M. Sorokin, Denis B. Shustov, Mikhail P. Shcheglov
Abstract: Transmission electron microscopy and the cathodoluminescence method have been used to study the transition region in 3C-SiC/6H-SiC heterostructures. It is shown that this region is, as a rule, constituted by alternating 3C-SiC and 6H-SiC layers, with possible inclusion of other silicon carbide polytypes. An assumption is made that this structure of the transition region can be explained in terms of the spinodal decomposition model
Authors: Giuseppe Pezzotti
Abstract: Photo- and electro-stimulated probes have been employed for quantitatively evaluating highly graded residual stress fields generated at the surface of alumina hip joints. Optical calibrations revealed large differences in probe size, which strongly affected the detected magnitude of residual stress. A comparison between the responses of Raman and fluorescence probes in polycrystalline alumina showed that the depth of those probes spread to an extent in the order of the tens of microns even with using a confocal probe configuration. On the other hand, the electro-stimulated luminescence emitted by oxygen vacancy sites (F+ center) in the alumina lattice represented a suitable choice for confining to a shallow volume the stress probe. The electron probe enabled confining the measurement depth to the order of the tens of nanometers. Maps of surface residual stress were collected on both main-wear and non-wear zones of an alumina femoral head. A comparison among stress maps taken at exactly the same location, but employing different probes, clarified the averaging probe effects on surface stress magnitude.
Authors: Giuseppe Pezzotti, Atsuo Matsutani, Maria Chiara Munisso, Wen Liang Zhu
Abstract: With the proliferation of several types and classes of high performance ceramic materials, the screening, evaluation and integration of new materials into structures and devices require a new and more effective approach. Evaluation on the nano-scale of the mechanical characteristics of new ceramic materials requires multiple complementary metrology tools. We report here about an advanced metrology tool, cathodoluminescence (CL) spectroscopy, which has a potential to rapidly screen and evaluate residual stress characteristics in advanced ceramic materials and structures. Nano-scale stress measurements are made in situ into an integrated metrology vacuum chamber in a field-emission gun scanning electron microscope (FEG-SEM). Complementing this tool, we also describe a new image analysis based on CL emission for fast screening and ranking of domain structures in ferroelastic ceramics. The end result of this paper is to show how crystallographic and mechanical characteristics of ceramics can be quantitatively characterized in a hybrid device combining electro-stimulated imaging and spectroscopic outputs.
Authors: M. Holla, Tzanimir Arguirov, Winfried Seifert, Martin Kittler
Abstract: We report on the optical and mechanical properties of Si3N4 inclusions, formed in the upper part of mc-Si blocks during the crystallization process. Those inclusions usually appear as crystalline hexagonal tubes or rods. Here we show that in many cases the Si3N4 inclusions contain crystalline Si in their core. The presence of the Si phase in the centre was proven by means of cathodoluminescence spectroscopy and imaging, electron beam induced current measurements and Raman spectroscopy. The crystalline Si3N4 phase was identified as β-Si3N4. Residual stress was revealed at the particles. While the stress is compressive in the Si material surrounding the Si3N4 particles tensile stress is found in the Si core. We assume that the stress is formed during cool down of the Si block and is a consequence of the larger thermal expansion coefficient of Si in comparison to that of β-Si3N4. Iron assisted nitridation of Si at temperatures below 1400 °C is considered a possible mechanism of Si3N4 formation.
Authors: Sandra Piazolo, David J. Prior, M.D. Holness, Andreas O. Harstad
Abstract: Annealing is an important mechanism of microstructural modification both in rocks and metals. In order to relate directly changes in crystallographic orientation to migrating boundaries the researcher has the option to investigate either samples where the grain boundary motion can be directly tracked or a series of samples exhibiting successively higher degrees of annealing. Here we present results from rock samples collected from two well characterised contact aureoles (a volume of rock heated by the intrusion of a melt in its vicinity): One quartz sample in which patterns revealed by Cathodoluminescence (CL) indicate the movement of grain boundaries and a series of calcite samples of known temperature history. Electron backscatter diffraction (EBSD) analysis is used to link the movement of grain, twin boundaries and substructures with the crystallographic orientation / misorientation of a respective boundary. Results from the quartz bearing rock show: (a) propagation of substructures and twin boundaries in swept areas both parallel and at an angle to the growth direction, (b) development of slightly different crystallographic orientations and new twin boundaries at both the growth interfaces and within the swept area, and (c) a gradual change in crystallographic orientation in the direction of growth. Observations are compatible with a growth mechanism where single atoms are attached and detached both at random and at preferential sites i.e. crystallographically controlled sites or kinks in boundary ledges. Strain fields caused by defects and/or trace element incorporation may facilitate nucleation sites for new crystallographic orientations at distinct growth interfaces but also at continuously migrating boundaries. Calcite samples show with increasing duration and temperature of annealing: (a) systematic decrease of the relative frequency of low angle grain boundaries (gbs), (b) decrease in lattice distortion within grains, (c) development of distinct subgrains with little internal lattice distortion, (d) change in lobateness of gbs and frequency of facet parallel gbs and (e) change in position of second phase particles. These observations point to an increasing influence of grain boundary anisotropy with increasing annealing temperature, while at the same time the influence of second phase particles and subtle driving-force variations decrease. This study illustrates the usefulness of using samples from natural laboratories and combining different analysis techniques in microprocess analysis.
Authors: Sergio Pizzini, Simona Binetti, Alessia Le Donne, E. Leoni, Maurizio Acciarri, Giancarlo Salviati, L. Lazzarini
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