AVS 49th International Symposium
    Surface Science Wednesday Sessions
       Session SS-WeM

Paper SS-WeM8
Dry De-intercalation in Layered Compounds upon Controlled Surface Charging in XPS

Wednesday, November 6, 2002, 10:40 am, Room C-112C

Session: New Opportunities and Technique Innovations
Presenter: H. Cohen, Weizmann Institute of Science, Israel
Authors: Y. Feldman, Weizmann Institute of Science, Israel
A. Zak, Weizmann Institute of Science, Israel
R. Tenne, Weizmann Institute of Science, Israel
H. Cohen, Weizmann Institute of Science, Israel
Correspondent: Click to Email
2H platelets and inorganic fullerene-like (IF) MS@sub2@ (M=W,Mo) powders, intercalated with alkaline (A=K,Na) atoms,@footnote 1@ are studied using controlled surface charging (CSC) in XPS.@footnote 2@ The degree of intercalation, expressed in terms of A/M concentration ratios, is found to tightly correlate with the presence of 'open' (hk0) edges, typically absent from the closed IF nanoparticles. Under strong electric fields, applied by an electron flood gun, diffusion of the intercalants towards the surface is observed. This out-diffusion process is negligible with low flood gun voltages, indicating that a critical field is needed for this type of dry de-intercalation. Diffusion rates out of 2H matrixes are generally higher than in corresponding IF samples, while those of K are far better than Na. These observations, closely related with the initial intercalation efficiency, provide helpful information about the actual intercalation states and their diffusion mechanisms. @FootnoteText@ @footnote 1@ A. Zak, Y. Feldman, H. Cohen, V. Lyakhovitskaya, G. Leitus, R. Popovitz-Biro, E. Wachtel, S. Reich and R. Tenne, JACS 124, 4747 (2002).@footnote 2@ I. Doron-Mor, A. Hatzor, A. Vaskevich, T. van der Boom-Moav, A. Shanzer, I. Rubinstein and H. Cohen, Nature 406, 382 (2000).