<p> Acceptor compounds of C60 and hexafluoride ions of group V elements (P, As, Sb)
were studied by infrared spectroscopy, x-ray diffraction and resistivity measurements.
C60(AsF 6)1.9 was formed by reacting C60 powder with AsF5 gas dissolved in liquid S02.
The AsF 6 ion was identified by a broad v3 absorption at 703 cm^-1, a shoulder at 681 cm^-1
and evidence of the sharp v4 absorption just below 400 cm^-1 in the infrared spectrum. The
low frequency modes ofC60 at 527 and 576 cm^-1 were unshifted in the reacted powder.
The T1u(3) mode of C60 , at 1183 cm^-1 was accompanied by neighbouring absorptions at
1194 and 1206 cm^-1, which were assigned tentatively to splitting of the triply degenerate mode. Three strong peaks at 1549, 1406 and 1322 cm^-1 observed in the spectra
were assigned to splitting of the threefold degenerate T1u(4) mode of pristine C60 at 1428
cm^-1. Heat treatments ofthe sample, with temperatures ranging up to 350°C, were
performed to thermally deintercalate the sample and to aid in identifying the infrared
modes. The decrease in intensity ofthe AsF6 absorptions and the return ofthe four strong
absorption lines ofundoped C60 indicated the successful deintercalation of the sample.
X-ray diffraction indicated that the C60 lattice, which had expanded to body centered
tetragonal to accommodate the AsF 6 ion, returned to the face centered cubic arrangement
of pristine C60 following heat treatments at 350 degrees Celcuis. The C60(AsF6)1.9 compound exhibited
semiconductor characteristics with an activation energy of 0.12 ± 0.05 eV. Possible interstitial sites for the AsF6- ion in the body-centered-tetragonal lattice of C60(AsF 6)1.9 have also been calculated. </p> <p> The PF6 ion, in the sample of C60 reacted with N02PF6 in S02, was observed in the
IR spectra by the broad v3 absorption at 830 cm^-1 and the sharp v4 absorption at 558 cm^-1
No strong absorption of NO2+ at 2360 cm^-1 was observed indicating that the sample was
not a simple mixture of the two powders. The C60 absorption lines, at 527, 576, I I 83 and
1428 cm^-1 were unshifted. However, the T1u(4) mode at 1428 cm^-1 showed asymmetric
broadening on the low frequency side and small absorptions flanking the T 10( 4) mode.
These features, although much less pronounced, may correspond to the shifting and
splitting observed in the T1u(4) mode ofthe C6o{AsF6)1.9 compound. The octahedral SbF6-
ion was identified in the sample of C60 powder reacted with N02SbF6 by the strong v3
absorption at 660 cm^-1. The C60 lines were unshifted, but small absorptions flanking the
T1u(4) mode, are again similar to the absorptions assigned to splitting in the C60(AsF6)1.9
compound. </p> / Thesis / Master of Science (MSc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/19249 |
| Date | 08 1900 |
| Creators | Francis, Ronald |
| Contributors | Datars, W. R., Physics |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
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