[en] Analyses have been made of the regularities in the change of properties of transuranium elements during their transition from lower to a higher degree of oxidation with a change in the atomic number of the elements. The results are of importance in forecasting the existence and properties of new valence forms of transuranium elements

[en] A review of studies published in 1975-1982 and devoted to investigation of redox properties of Np and Pu ions and their reactions is given. The main attenitin is paid to kinetics and mechanism of these reactions. New experimental and calculation data on ion pair potentials and reaction thermodynamics are considered. Redox reactions in complexing. solutions, organic solvents, molten salts and heterogeneous systems are discussed

[en] Consideration is being given to methods of preparation, structure, physical and chemical properties of some TUE compounds from neptunium up to einsteinium inclusively. The following compounds were considered among others: hydrides, binary and mixed carbides, silicides, simple and complex nitrides, phosphides, arsenides, antimonides, bismuthides, simple and mixed oxides, binary and mixed sulfides, oxysulfides, selenides, oxyselenides, tellurides, oxytellurides, mixed compounds with elements of the 5th and 6th groups of the periodic system

[en] Methods of preparation, structure, physical and chemical properties of some compounds of transuranium elements in various oxidation degrees from neptunium to californium inclusively are considered. The following compounds were studied among others: hydroxides of neptunium (4-6), plutonium (3-6), americium (3-5), curium (3), berkelium (3), californium (3), peroxides of americium (3), neptunium (4, 5), plutonium (4), borohydrides (and their substituted) neptunium (4), plutonium (4)

[en] A series of compounds of general composition MAm(C₂O₄)₂xnH₂O, where M-Na, NH₄, or Cs, has been synthesized. Concentration values, of sodium, ammonium or cesium oxalates are found, at which different crystallohydrates are stable. They are isostructural to previously identified phases of the composition KAm(C₂O₄)₂xnH₂0, Where p=5, 3.5 and 2.5. COpditions for crystallohydrate CsAm(C₂O₄)₂x0.5H₂O separation are established. Behaviour of praseodymium and terbium under the conditions studied is also considered. Using the method of thermogravimetry it is shown that NH₄Am(C₂O₄)₂x5H₂O begins to lose water at approximately 90 deg C and burns at approximately 330 deg C with the formation of AmO₂

[en] Treatment of Np(IV) oxalate with an NH₄OH solution produces an Np hydroxide with the minimal amount of oxalate and Np(V) impurities that is suitable for preparing Np sols. Peptization using HCl, HNO₃, and CH₃CO₂H produces stable Np(IV) sols with 2-2.5 M Np and less than 4% Np(V). Their spectra are presented

[en] General characteristic of transuranium elements (TUE) from neptunium up to einsteinium inclusively is given. Nuclear properties of major isotopes and physicochemical properties of elements in metallic state are presented. Electron structure, oxidation states, ion TUE forms and their corresponding absorption spectra in solutions are considered. TUE complexing in solut ions, redox reactions, as well as the methods for TUE preparation in assigned oxidation states are discussed

[en] Neptunium (5) behaviour in molybdate solutions is studied. M₃NpO₂Mo₄O₁₄ composition compounds where M is NH₄ or K, (NpO₂)₂MoO₄xnH₂O composition compounds where n is 1.5-2.0 and (NpP₂)₂MoO₄ are separated. Conditions for preparation of these compounds are studied, IR spectra, data of X-ray phase analysis are presented. (NpO₂)₂MoO₄ is shown to be stable at the temperature upto 500 deg C; it is suggested to use this compound as a target for neutron irradiation

[en] Disproportionation of Pu(5) has been studied in hydrochloric acid solutions of methanol and its mixture with benzene and acetonitrile. In hydrochloric methanol solutions plutonium(5) has been shown to disproportionate irreversibly with the formation of chloride complexes of Pu(4) and Pu(6). As compared with aqueous solutions the rate of disproportionation increases greatly. An effect of concentration of HCl, water, and additives of benzene and acetonitrile on the reaction rate constant has been studied. Addition of benzene and acetonitrile accelerates the reaction sharply, whereas addition of water decreases monotonously the reaction rate. HCl accelerates the reaction

[en] A method is described for reducing the concentration of neptunium and plutonium from alkaline radwastes containing plutonium and neptunium values along with other transuranic values produced during the course of plutonium production. The OH^- concentration of the alkaline radwaste is adjusted to between about 0.1M and about 4M. [UO₂(O₂)₃]^4- ion is added to the radwastes in the presence of catalytic amounts of Cu⁺², Co⁺² or Fe⁺² with heating to a temperature in excess of about 60 C or 85 C, depending on the catalyst, to coprecipitate plutonium and neptunium from the radwaste. Thereafter, the coprecipitate is separated from the alkaline radwaste. 2 figs