X-ray diffaction evidence for nonstoichiometric rubidium-c60 intercalation compounds.
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.
Zhu
Q
Q
Zhou
O
O
Coustel
N
N
Vaughan
G B
GB
McCauley
J P
JP
Romanow
W J
WJ
Fischer
J E
JE
Smith
A B
AB