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Due to an oversight, the captions for figures 1 and 2 were transposed. The correct figure captions are given below.   Figure 1. A transmission electron micrograph of 50 Torr He fullerene soot showing coagulated balloons which are suggested to be sealed containers of defective free radical material. Notice that the shape of the particles suggests that the balloons contain several structures held together initially by Van der Waals forces and then sealed by a number of coats of carbon atoms in the gas phase.   Figure 2. Small-aperture transmission electron diffraction of 50 Torr He soot. The spot pattern shown is consistent with a collection of randomly orientated graphitic microcrystallites as shown in figure 3.

Online extraction of fission products, such as the medical isotope Mo-99, is a key advantage of the proposed molten salt nuclear reactor design. The chemical and structural behavior of Mo solvated in fluoride salt has been relatively unknown. Ab initio molecular dynamics simulations were employed to examine the behavior of molybdenum in the molten salt FLiNaK (LiF-NaF-KF) for oxidation states between 0 and 6+. Mo complexation was found to vary with the Mo oxidation state, with lower oxidation states tending to result in complexes with more molybdenum ions. Complexes containing multiple Mo ions were observed for all Mo oxidation states studied except 5+ and 6+. A relationship between the solubility of a complex and electronic isolation of a complex in a molten salt is explored using the Bader atoms in molecule electron density partitioning scheme, with more volatile complexes exhibiting greater electronic isolation. The impacts of UF4 and H2O on the predominant molybdenum species are also considered. While no impacts on Mo behavior by UF4 were observed, Mo–O interactions may inhibit the formation of complexes containing multiple Mo ions.

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Molten salt mixtures have important applications in, for example, industrial metallurgical processes, energy storage for solar plants, and the development of advanced nuclear reactor systems. Several unanswered questions in these systems involve the thermodynamics of minor components in the molten salt solution. Consequently, we examine molten salt systems using electrochemical thermodynamics, published experimental data, and atomistic simulations to accurately characterize interactions between a minor component and the base salt for multiple salts. The utility of an infinite dilution reference state is demonstrated and used to characterize the range over which solute-solvent interactions dominate over solute-solute interactions for minor components. Under such conditions, the activity is readily defined and cell potential can be easily determined as a function of concentration with use of an appropriate standard potential. Experimental data show that reactions can proceed at very different potentials in different salt melts, and molecular dynamics simulations are used to quantify differences between salts. Simulations show that the chemical potential of an anion varies between melts as influenced by the different cations present in each melt. Hence, attempts to use a common reference reaction for different salt mixtures are at best an approximation. Simulations also demonstrate that solute-solute interactions become significant at lower concentrations if the minor component includes an anion that is different from that of the base salt. This work helps to enhance our understanding of the behavior of minor components in molten salts, which is important for the development of future energy technologies.