Abstract
Core-level photoemission studies of alkali fulleride thin films indicate alkali bonding configurations that can be associated with octahedral and tetrahedral interstitial sites of the lattice. For , the K 2p core-level results suggest nucleation for K concentration as low as x∼0.1 with occupation of both octahedral and tetrahedral sites. In contrast, the Rb 3d and Cs 4d core-level spectra show filling of only octahedral sites until x∼1, forming phases. For intercalation beyond x∼1, the fcc tetrahedral sites of Rb are occupied as forms. Intercalation with K or Rb beyond x∼3, or with Cs beyond x∼1, results in a spectral feature that is consistent with formation of a body-centered phase with equivalent tetrahedral interstitial sites. Results for suggest that Na ions occupy off-center positions in the large octahedral sites. Studies of ternary fullerides (x+y<3) demonstrate preferential filling of the octahedral sites by the larger ion.
- Received 26 October 1992
DOI:https://doi.org/10.1103/PhysRevB.47.9870
©1993 American Physical Society