Abstract
Electron-diffraction results are reported in the temperature range K for graphite-Rb intercalation compounds based on highly oriented pyrolytic graphite host material. Annealed stage samples show the simple graphite pattern below ∼ 300 K, corresponding to a in-plane intercalate superlattice ordering with ,,, interlayer intercalate stacking order. A reversible transition is made at ∼ 300 K to a superlattice, but lacking ,,, stacking. The higher-stage compounds () exhibit commensurate superlattices below a temperature which decreases with increasing stage index from 170 K for . As is increased above , the higher-stage compounds exhibit a reversible transition to another ordered structure which is present until the transition to a high-temperature phase, observed at 620 K for . The structural transition at between the two ordered phases is accompanied by a dramatic change in the bright-field real-image micrograph, taken on the same portion of the sample as the electron-diffraction patterns. The observation of a second ordered phase above in the Rb compounds is in contrast with the disordered phase reported previously for second-stage K compounds.
- Received 8 October 1979
DOI:https://doi.org/10.1103/PhysRevB.21.3491
©1980 American Physical Society