The published data on the structures and properties of The published data on the structures and properties of crystalline actinide compounds having mutually coordinated crystalline actinide compounds having mutually coordinated AnO AnO 2 or AnO or AnO 2 2 cations as structural elements are surveyed. cations as structural elements are surveyed. This cation ± cation interaction is an important structure-forming This cation ± cation interaction is an important structure-forming factor for many crystalline compounds of Np( factor for many crystalline compounds of Np(V V) and U() and U(VI VI). It ). It strongly affects their UV-Vis and IR spectra as well as other strongly affects their UV-Vis and IR spectra as well as other properties. Differences and similarities between the cation ± cation properties. Differences and similarities between the cation ± cation interactions of actinide ions in solutions and crystals are dis-interactions of actinide ions in solutions and crystals are discussed. The bibliography includes 114 references cussed. The bibliography includes 114 references. .

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SummaryThe interactions of Pu(N) and Pu(VI) in alkaline media with some metal hydroxides and oxides commonly found in Hanford Site tank wastes were studied. The properties of mixed hydroxide systems of Pu(IV) with various metal ions mi@), Fe(III), C o o , Al(m), Cr(m>, Zr(IV), La(IlI), and U(VI)] were investigated at variable component ratios using physicalchemical methods. The interactions of P u O with Al(lII), Fe(III), and Cr(IlI) also were studied.It was shown by infrared (IR) spectroscopy that, except for the system Pu(IV)-Ni(II), Pu(IV) interacts with all the listed metal ions and affects their interatomic bonding. The locations of IR absorption bands of the mixed hydroxides change irregularly compared with the spectra of pure components, with change in the Pu:metal mole ratio of from 1:lO to 1O:l. The changes occur both for the valent and deformation vibration bands of hydroxyl ions and water at 3600 to 3100 and 1750 to 1250 cm-' and for the vibrations of metal-oxygen (M-0) bridging bonds in the range of 1050 to 850 cm-'. In the Pu(IV)/Ni(II) system, the IR spectra are equivalent to the sum of the individual components precipitated separately from alkaline solution.The separate precipitation of h(N) hydrous oxide and Ni(OH), upon adding NaOH solution to acidic solution containing both Pu(N) and Ni(II) nitrate was confirmed by studying the dissolution rate of the resulting precipitate in 3 M HCl at 60°C. No difference in plutonium dissolution behavior was found for pure PuO,-xH,O and the products obtained by alkaline precipitation of 1: 1 mole ratio Pu(N):Ni(II) mixtures, aged for 1 hour at 70"C, over a wide range of NaOH concentrations. Similar results were obtained for the Pu(IV)-Al(III) system. Only trace amounts of aluminum were detected in pUO,.xl&O precipitates formed even in relatively dilute NaOH solutions.

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