(00l) x-ray diffraction study of stage 1 α and β phases of graphite--CsBi/sub x/

Results are reported of (00l) x-ray studies of the α(I/sub c/ = 10.65 A) and β(I/sub c/ = 11.49 A) phases of stage 1 graphite--CsBi/sub x/ ternary intercalation compounds that are air stable. The integrated intensities of the (00l) x-ray lines are analyzed in terms of a centrosymmetric sandwich model that consists of two layers each of Cs, Bi, and C. The results of these analyses indicate that the Bi layers are nearly centered in the cell as suggested by Lagrange et al. [Synth. Met. 12, 201 (1985)]. Furthermore, stoichiometries of the α and β phases are found to be Cs/sub 0.99/Bi/sub 0.43/C4 and Cs/sub 0.83/Bi/sub 0.81/C4, respectively. The β phase is found to contain nearly twice as many Bi atoms. The sample mass change upon intercalation is in good agreement with the x-ray analyses. The substantial difference in the Bi concentration in the α and β phases would be expected to have strong influence on the superconducting properties of these graphite intercalation compounds (GIC's)