title: X-ray diffaction evidence for nonstoichiometric rubidium-c60 intercalation compounds.
abstract: Powder x-ray diffraction at 300 K on equilibrated samples of several nominal compositions chi in Rb(chi)C(60) is reported. In addition to the face-centered cubic (fcc) (chi = 3, superconducting), body-centered tetragonal (chi = 4), and body-centered cubic (bcc) (chi = 6) stoichiometric phases, direct evidence for a dilute fcc doped phase, 0 x c </= 1, and for a substoichiometric bcc phase, chi approximately 5, is presented. In contrast, chi = 3 and chi = 4 appear to be line phases with nearly zero solubility of Rb vacancies and interstitials at 300 K. These results are summarized in a provisional binary phase diagram.
authors.forename: Q
authors.initials: Q
authors.lastname: Zhu
authors.forename: O
authors.initials: O
authors.lastname: Zhou
authors.forename: N
authors.initials: N
authors.lastname: Coustel
authors.forename: G B
authors.initials: GB
authors.lastname: Vaughan
authors.forename: J P
authors.initials: JP
authors.lastname: McCauley
authors.forename: W J
authors.initials: WJ
authors.lastname: Romanow
authors.forename: J E
authors.initials: JE
authors.lastname: Fischer
authors.forename: A B
authors.initials: AB
authors.lastname: Smith