Selective deposition of UCl4 and (KCl)x(UCl4)y inside carbon nanotubes using eutectic and noneutectic mixtures of UCl4 with KCl

UCI4 and compositions of the form (KCI)(x)(UCI4)(y) have been selectively deposited inside multiple-walled carbon nanotubes (MWTs) via capillary action using both eutectic and noneutectic mixtures of UCl4 with KCl. The deposition conditions were determined from the pseudobinary KCl-UCl4 phase diagram, which contains two eutectic melting compositions at 50 mol% KCl:50 mol% UCl4 and 73.2 mol% KCl:26.8 mol% UCl4, and also from surface tension/composition data reported in the literature. The encapsulated products were investigated by HRTEM and EDX incorporating both nanometer and sub-nanometer scale electron probes. Following preliminary characterization, the selectively encapsulated UCl4 was allowed to oxidize in air for 14 days, but only a relatively small amount (ca. 2%) of a crystalline oxidized product of the form U(CI,O)(x) was observed inside the MWTs. Some MWTs selectively filled with UCl4 showed evidence of spiraling (helical) crystal growth. (C) 1998 Academic Press.