Background
Lanthanum Carbide (LaC2) is made by putting graphite and lanthanum in a DC arc furnace. A method for making macroscopic quantities of C60 and the confirmation of the hollow, cagelike structures was published in 1990 by Kratschmer and co-workers. This was followed by the publication of methods for higher fullerenes (C70 and higher). In 1993, scientists discovered how to make a compound which is not as susceptible to moisture and air. They made containers to hold buckminsterfullerenes, or buckyballs; therefore they nicknamed the containers ‘buckyjars’. A few US patents were issued to universities in the mid-1990s; experiments with manufacturing techniques have continued at universities around the globe, including India, Japan, and Sweden.
In LaC72, the lanthanum appears to stabilize the carbon cage. A 1998 study by Stevenson et al. verified the presence of LaC72 as well as La2C72, but empty-cage C72 was absent, based on laser desorption mass spectrometry and UV−vis spectroscopy. A 2008 study by Lu et al. showed that La2C72 do not adhere to the isolated pentagon rule (IPR), but has two pairs of fused pentagons at each pole of the cage and that the two La atoms reside close to the two fused-pentagon pairs. This result lends additional support to the idea that the carbon cage is stabilized by the La atoms.
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