Paramagnetische elektronenresonanz (EPR) in polykristallinen graphiten bei hohen temperaturen

✍ Scribed by M.J. Paersch; F.H. Franke; W. Schroller

• Book ID: 102993818
• Publisher: Elsevier Science
• Year: 1977
• Tongue: English
• Weight: 455 KB
• Volume: 15
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(77)90009-4

✦ Synopsis

EPR measurements were carried out on polycrystalline graphites in a temperature range of 300-1300 K. A special temperature unit permitted stable and interference-free adjustment of the sample temperature up to 1400K (Fig 1). The powdered samples based on natural (RWA) and an artificial extruded graphite (RWS) respectively were separated into grains of small size (53pm), dispersed and evacuated, to avoid troublesome oxygen and skin-depth effects. It was possible to obtain the crystallite tensor components of the g-factor (Figs. 2,3) and the crystallite line-width parameters (Fig. 4) from the asymmetrical powder spectrum by computer analysis, assuming an axial symmetry of the crystalhtes within the grains. One can thereby determine the average orientation -?-of the crystallites within the grains, expressed by sm 4, where 4 is the angle between the symmetry axis of the grain and the perpendicular on the basal plane of a crystallite. The anisotropy Ag = g3-g, = f(l/T) of &he graphites