Yoshihiro Iwasa

Synthesis and structure of BaxC70

Abstract We have investigated the structural sequence of BaxC70 binary systems. X-ray diffraction measurements revealed that there exist at least four stable phase at x=3, 4, 6, and 9. Among them, structural models are presented for Ba3C70 and Ba3C70. Ba9C70 takes an analogous structure to A15-Ba3C60, but the unit cell is distorted to tetragonal with the cell doubling. Ba9C70 is fcc, involves a distorted cube of Ba8 in the octahedral interstices. This x=9 structure is also known in K9C70 as a saturated phase.

NMR studies of ammoniated alkali fullerides

13C-NMR measurements of (NH3)xK3C60 were carried out for three samples with different NH3 content of x=1.14(#1), x=1.05(#2), and x=0.98(#3). 13C-NMR spectrum for x=0.98(#3) shows an anomalous spectral broadening, whereas a distinct anomaly is hardly observed for the off-stoichiometric sample with x=1.14(#1). In the magnetic ordered state at 4.2 K, although unusual spectral broadening ascribed to the AF order was observed for all sample. We found, however, the linewidth depends on the sample-quality, i.e., stoichiometry of NH3 content (∼0.8, 1.3, and 3 MHz for x=1.14(#1), 1.05(#2), and 0.98(#3), respectively). Present studies reconfirmed that the lines A and B are inherent in AF ordering and the off-stoichiometric ammoniation obstruct the AF ordering.