Angle-dependent X-ray absorption near edge structure and X-ray diffraction measurements were performed on a Poco graphite and on glassy C in order to determine their long-range and short-range orders. The Poco graphite was a well-graphitized polycrystalline material, while the glassy C exhibited hardly any long-range order. The X-ray absorption near edge structure spectra revealed graphite-like short-range order. By using a mass spectrometry method, the diffusion of 7Li in both materials was investigated for Li atomic fractions of between 0.1 and 300ppm at temperatures ranging from 1000 to 1400K. The Li was found to be released from the Poco graphite mainly via intragranular diffusion and not by Knudsen diffusion through the open interconnected pores. The inaccessible porosity of the glassy C was equal to the total porosity. That is, open pores were not present. The Arrhenius equations for Li diffusion in the Poco graphite and in the glassy C were:

D (cm2/s) = 3 x 104 exp[-2.27(eV)/kT]

and

D (cm2/s) = 1.5 x 106 exp[-3.1(eV)/kT]

respectively.

The Diffusion of Li in Poco Graphite and Glassy Carbon at Low Concentrations and High Temperatures. Jungblut, B., Hoinkis, E., Döbler, U., Meyerheim, H.L.: Berichte der Bunsengesellschaft für Physikalische Chemie, 1989, 93[11], 1317-22