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The structure factors of molten LiNO3, RbNO3and AgNO3and the 1:1 LiNO3-RbNO3mixture have been determined over a wide range of momentum transfer by neutron total scattering measurements using a pulsed spallation neutron source. Least-squares analyses applied to the intra-ionic part of the structure factors have revealed the geometry of nitrate ions to be equilateral triangular (the D3hsymmetry) in the melts, independent of the cations involved. The radial distribution function (RDF) of the AgNO3melt has indicated that about four nitrate ions are bound to an Ag+ion as a monodentate ligand with the shortest Ag-O distance of 240 pm. The contact between lithium atoms and nitrate ions was also evidenced at about 190 pm in the RDF of the melts containing lithium ions, but the orientation of the nitrate toward lithium ions was not conclusive in the present study.

Pulsed neutron diffraction Pulsed neutron diffraction measurements have been performed on molten (7Li, K)C1 and (7Li, Na, K)Cl mixtures of the eutectic composition to determine the nearest neighbour distance between Li+and Cl-ions. Owing to the negative scattering length of the 7Li nucleus, this contribu­tion becomes negative in the radial distribution function and can be separated from the other contributions. The nearest neighbour distance between Li+ion and Cl-ion is found to be 240 pm in both the binary and ternary mixtures.

X-Ray scattering measurements of 2.78 and 5.56 molal aqueous solutions of caesium iodide and 2.78 and 6.05 molal lithium iodide were carried out at 293 and 343 K Differences in the radial distribution functions (DRDFs) have been obtained between the caesium iodide and lithium iodide solutions of similar composition, the latter being taken as a reference for the data analysis of the former. The DRDFs show a peak arising from Cs - I contact-ion-pairs at 390 pm for all the caesium iodide solutions. The hydration structure of the caesium and iodide ions has been revealed. Effects of the concentration and temperature on the formation of ion-pairs and on the hydration structure of the ions are discussed