Hamburg 2001 – wissenschaftliches Programm
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M: Metallphysik
M 10: Diffusion und Punktdefekte II
M 10.4: Fachvortrag
Montag, 26. März 2001, 12:30–12:45, S12
Study of electron and neutron irradiated silicon carbide 6H-SiC by means of positron annihilation and x-ray diffraction — •A.A. Rempel1,2,3, K.J. Reichle2, W. Sprengel2, H.-E. Schaefer2, C. Seitz3, R. Hock3, and A. Magerl3 — 1Institute of Solid State Chemistry, Russian Academy of Sciences, 620219 Ekaterinburg, Russia — 2Institut für Theoretische und Angewandte Physik, Universität Stuttgart, 70550 Stuttgart, Germany — 3Lehrstuhl für Kristallographie und Strukturphysik, Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
Single crystalline silicon carbide 6H-SiC with hexagonal structure P63mc before and after electron and neutron irradiation was investigated by two different techniques - by positron annihilation which is sensitive to the free volumes on the atomic scale and by x-ray diffraction which give information about the crystal symmetry and the distribution of defects. It was found, that electron irradiation is accompanied by a strong rise of the positron lifetime up to 210 ps. An even stronger increase of the positron lifetime was found earlier for neutron irradiated silicon carbide. Carbon and silicon vacancies which were identified by positron annihilation do not affect the x-ray diffraction pattern strongly. Since the atoms are distributed in a lattice randomly they do not reduce the crystal correlation length and increase only to a small extent the background of the pattern. In contrast to that the irradiation induced interstitial atoms are mobile at ambient temperature, they create dislocations and are detected in 6H-SiC by diffuse scattering and broadening of the Bragg spots up to 0.03 nm−1 .