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The use of composite cements consisting of calcium aluminate and calcium sulfate for solidification of aqueous NaNO3 concentrates (liquid radioactive waste imitators) is considered. Matrices that meet the requirements to cemented solid radioactive waste were obtained. The effects of the composition of the formulation on the properties of the matrix were studied. [ABSTRACT FROM AUTHOR]

The article studies the possibility of using a matrix of gibbsite and kuzelite for the preservation of liquid radioactive wastes consisting of aqueous NaNO3 concentrates. The matrix is formed during the solidification of these wastes with cement, consisting of calcium aluminate and gypsum. The requirements for cemented solid waste are met by a matrix obtained from a mixture of the following composition: 45.2%-NaNO3 solution 53.04%; gypsum—5.4%; calcium aluminate—36.16%; diatomite powder treated with polydiallyldimethylammonium chloride (polyDADMAC)—5.4%. The matrix has the following characteristics: ratio of matrix and cemented solution volumes—1.45; average 137Cs leaching rate for 90 days—1.4∙10−4 g/(cm2∙day); strength—15.2 MPa, including after the tests for water resistance, 30 freezing-thawing cycles, and irradiation to a dose of 1 MGy—6.8, 15.4, and 9.6 MPa, respectively. [ABSTRACT FROM AUTHOR]

Formation of the metal is observed under irradiation of methanol-containing aqueous solutions of cadmium salts with accelerated electrons. The process of precipitation of the metal and its properties was examined. The radiation-chemical yield is (1.7 ± 0.2) × 10-2 g kGy. The efficiency of the radiation-induced reduction of a number of other metals in aqueous media: copper, lead, and thallium, was substantiated. The method may be promising for obtaining deposits of pure and amorphous metals from aqueous solutions of their salts and for purification of aqueous effluents containing these toxic metals. [ABSTRACT FROM AUTHOR]

Metal-ceramic materials based on NiFe2O4 and Fe2O3 with additions of copper oxide and transition metals Cu, Ni, Co, and Fe were obtained. Changes in the phase content of materials based on iron oxide were shown, and the electrical conductivity of the obtained composites was studied. Samples of inert anodes were tested in an electrolytic cell; high resistance of cermets NiFe2O4 + Cu, Ni against alumina-cryolite melts and stability of aluminum electrolysis were established. [ABSTRACT FROM AUTHOR]

The reaction of the ozone-oxygen mixture with aqueous suspensions of Np(IV) and Pu(IV) oxalates was studied. Both metal cations and oxalate anions are oxidized in the process. The final products are Np(VI) and Pu(VI) hydroxides. The composition of Np(VI) hydroxide was confirmed by X-ray diffraction analysis. Oxidation of Np(IV) oxalate with oxygen leads to the accumulation of Np(V) oxalate and oxalic acid in the solution. At incomplete oxidation of Np(IV) oxalate with ozone in water, Np(V) is also accumulated. Heating considerably accelerates the ozonation. The possible reaction mechanism is briefly discussed. The Np(V) and Np(VI) ions participate in the catalytic cycle of the decomposition of oxalate ions with ozone. [ABSTRACT FROM AUTHOR]

The structure and properties of the needle-like phase of crystalline compounds of the general composition Co(NH)NpO· nHO, precipitated from alkaline Np(VII) solutions with [Co(NH)] ions, were studied. The needle-like phase under the layer of the mother liquor is unstable and transforms into a platelike phase identified as [Co(NH)][NpO(OH)]·2HO ( 1). In the structure of 1, all the Np atoms are equivalent, but the Mössbauer spectrum recorded at a liquid helium temperature revealed the presence of two nonequivalent Np atoms. The isolated needle-like phase, according to single crystal X-ray diffraction data, at 100 K has the composition [Co(NH)][NpO(OH)]·4HO ( 2). In the structure of 2, there are two crystallographically independent Np(VII) atoms. The Np(1) atom is in the inversion center, and the Np(2) atom occupies a general position. The structure of 1 was additionally refined, and the structures of 1 and 2 were compared. Both compounds have a similar structure, but the structure of 2 is less ordered, and the formation of both structures is influenced by hydrogen bonds involving water molecules and [NpO(OH)] ions. In the structure of 1, hydrogen bonds of type O-H···O form a three-dimensional network. In the structure of 2, the O-H···O hydrogen bonds are weaker and form a two-dimensional network. In the structure of 1, there are two water molecules per [NpO(OH)] anion, and in the structure of 2, 4/3 water molecules. Needle-like phase 2 in contact with solutions transforms into stable platelike phase 1 with dense packing and a three-dimensional system of hydrogen bonds. The size of needle-like crystals increases, and the rate of their transformation into platelike crystals decreases with increasing alkali concentration and decreasing temperature. The influence of the experiment conditions on the interaction of Np(VII) with [Co(NH)] ions in weakly alkaline (0.05-0.15 M) solutions was also studied. The precipitates formed are characterized by the ratio [NpO(OH)]: [Co(NH)] = 2: 1 and are identified as the known compound LiCo(NH)NpO(OH)·2HO. [ABSTRACT FROM AUTHOR]

Actinide(IV) tribromoacetates of the composition [An(CBrCOO)(HO)] (An = Th, U, Np) were synthesized and studied. Their structural feature is the formation of electrically neutral dimeric complexes. The surrounding of the An(IV) atoms in the dimers is formed by the oxygen atoms of six CBrCOO anions and two water molecules; the coordination number of An(IV) is 9, and the coordination polyhedron can be described as distorted base-monocapped tetragonal antiprism. Four independent CBrCOO anions in the structure are coordinated to the An(IV) atoms in different fashions: monodentate, bidentate chelate, and bidentate bridging. Hydrogen bonding links the dimers in infinite chains along [010] direction. The hydrogen bonding noticeably influences the geometric characteristics of the coordination surrounding of the An(IV) atoms. [ABSTRACT FROM AUTHOR]

Double Ln(III) malonates of two different compositions crystallize from malonate solutions containing [Co(NH)] ions. Lanthanides of the beginning of the series form compounds of the composition [Co(NH)][Ln(mal)]·6HO ( I) (Ln = La, Ce, Pr, Nd; mal = CHO), and those of the end of the series form compounds of the composition [Co(NH)][Ln(mal)(Hmal)(HO)]· nHO ( II) (Ln = Tb, Ho, Er, Tm). Structure I is based on trimeric anionic complexes [Ln(mal)] linked with each other to form a branched 3D network with [Co(NH)] cations and water molecules accommodated in large voids. The coordination mode of malonate ions in I with the coordination capacity equal to 5 was unknown previously for lanthanide malonate compounds. The Ln(1) atom has the maximum possible for malonate compounds coordination number (CN) 12, and the Ln(2) atom has CN 9. The structure of II consists of anionic chains [Ln(mal)(Hmal)(HO)] between which the [Co(NH)6] cations and water molecules are arranged. One independent malonate ion in the structure is coordinated in the bidentate chelate fashion to the Ln(1) atom, and the other independent chelate-bridging ligand is coordinated in the bidentate fashion to the Ln(2) atom and in the monodentate fashion to the Ln(1) atom. As a result, tetrameric fragments linked in anionic chains are formed in the structure of II. The Ln(1) and Ln(2) atoms have CN 8. [ABSTRACT FROM AUTHOR]

Precipitation of salts M[NpO(OH)]· nHO (M = Na, K, Rb, Cs) from concentrated alkali solutions at low temperatures (about −10°C) was studied. From solutions with [OH] > 9.5 M, these compounds are isolated as coarse black crystals in high yield without impurity of other phases. The K, Rb, and Cs salts crystallize in the form of the previously studied compounds K[NpO(OH)]·2HO and M[NpO(OH)]·3HO (M = Rb, Cs). In the case of Na, a new hydrate Na[NpO(OH)]·6HO was obtained, and its crystal structure was determined. Crystals of the hexahydrate consist of centrosymmetrical tetragonal-bipyramidal anions [NpO(OH)], crystallographically independent Na(1) and Na(2) cations, and water molecules. The coordination surrounding of the Np atom is characterized by noticeable difference (Δ = 0.0203 Å) in the Np-O bond lengths in the equatorial plane of the bipyramid. The [NpO(OH)] anions are combined with the Na(2) cations to form infinite chains [Na(2)NpO(OH)(HO)] in such a manner that the lateral edges of the anion are simultaneously the lateral edges of the Na(2) coordination polyhedron. Incorporation of one of the two crystallographically independent O atoms of the NpO group into the Na(2) coordination surrounding is responsible for a noticeable difference in the Np-O bond lengths in the equator of the [NpO(OH)] anion. The types of hydrogen bonding in the structures of Na3[NpO(OH)]· nHO ( n = 0, 2, 4, 6) are compared. [ABSTRACT FROM AUTHOR]

Complexes of 1,10-phenanthroline (phen) with Np(V) and Pu(V) benzoates of the compositions NpO2(phen)(OOCC6H5) and PuO2(phen)(OOCC6H5) were synthesized. A powder X-ray diffraction study showed that these compounds, depending on the preparation conditions, exist in the form of two phases having essentially the same composition but different powder patterns. The phases isolated from hot (70–100°C) solutions are isostructural with the previously described complexes AnO2(bipy)(OOCC6H5) (An = Np and Pu, bipy = 2,2′-bipyridine), i.e., in their structure there are dimeric (AnO2) cations formed by mutual coordination of two AnO ions via “yl” oxygen atoms. The compounds AnO2(phen)(OOCC6H5) prepared by slow crystallization in the cold or at weak (up to 45°C) heating are isostructural with each other but appreciably differ in the structure from the high-temperature phases. The electronic absorption spectra of the compounds and their thermal behavior were examined. [ABSTRACT FROM AUTHOR]

Heteroligand compounds AnO2(bipy)OOCC6H5 (An = Np, Pu; bipy = α,α-bipyridine, C10H8N2) were synthesized and studied. It follows from powder X-ray patterns that these compounds are isostructural. Their unit cell parameters, determined by indexing of the powder X-ray patterns, are as follows: a = 9.2162 (7), b = 10.2339(8), c = 17.4083(17) Å, and β = 96.48(1)° for Np and a = 9.1983(18), b = 10.2052(18), c = 17.370(3) Å and β = 96.51(1)° for Pu. The compounds crystallize in the monoclinic system space group P21/ n, Z = 4. The electronic absorption spectra of crystalline compounds suggest pentagonal-bipyramidal surrounding of the central atom and the prescence of cation-cation bonds with AnO ions acting as monodentate ligands with respect to each other. The IR spectra of the compounds were recorded, and their thermal behavior in air was studied. [ABSTRACT FROM AUTHOR]

New complexes of Np(V) and Pu(V) with α,α′-bipyridine of the composition AnO2(bipy) · OOCC2H5·H2O (An = Np, Pu) were synthesized. They are isostructural to each other; however, they differ essentially in the structure and characteristics from the similar complexes of An(V) formates and acetates. The new compounds were characterized by powder X-ray diffraction, thermal analysis, electronic absorption spectroscopy, and IR spectroscopy. [ABSTRACT FROM AUTHOR]

Crystalline NpO2OOCH·C10H8N2· nH2O and NpO2OOCCH3·C10H8N2·H2O were synthesized by the addition of a small excess of α,α′-bipyridine to neutral Np(V) formate and acetate solutions. In the wet state and after drying in air, these compounds have essentially different powder X-ray patterns. In the dry state, these compounds are monohydrates. In formate solutions with addition of α,α′-bipyridine, Pu(V) behaves similarly, whereas attempts to prepare the related Pu(V) acetate complexes failed. The Np(V) and Pu(V) compounds AnO2OOCCH3·C10H8N2· nH2O are isostructural. According to the results of spectrophotometric studies, the coordination polyhedron of the central atom in all the compounds studied is a pentagonal bipyramid. The IR spectra were recorded and the thermal behavior of the compounds was studied. [ABSTRACT FROM AUTHOR]

Double Pu(V) and Np(V) acetates of the compositions BaPuO2Ac3·2H2O and SrAnO2Ac3·3H2O with An = Pu and Np were synthesized in a well-crystallized form. In the dry state the compounds are stable in prolonged storage and are not hygroscopic. The plutonyl(V) and neptunyl(V) salts of the similar composition are isostructural. The IR spectra of the compounds were measured, and their behavior in heating was studied. [ABSTRACT FROM AUTHOR]

Synthesis of Pu(V) sulfates from aqueous solutions was studied, and previously unknown Co(NH3)6PuO2(SO4)2·2H2O was prepared and characterized by X-ray diffraction analysis. It was found that it is isostructural to neptunyl(V) analog. Thermal behavior of this compound in air was studied, and its IR spectrum was recorded and analyzed. The factors preventing formation of Cs3PuO2(SO4)2·2H2O and simple sulfates of the composition (PuO2)2SO4· xH2O were examined. [ABSTRACT FROM AUTHOR]

Neptunium(V) at its relatively high concentrations in oxalate solutions forms, along with the mono-and bioxalate complexes, the intermediate binuclear anion (NpO2)2(C2O4). This anion gradually crystallizes from cold aqueous-ethanol solutions in the form of the compound Na4(NpO2)2(C2O4)3 · 6H2O, and from hot aqueous-ethanol solutions, in the form of a lower hydrate, Na4(NpO2)2(C2O4)3 · 2H2O. Both compounds were characterized by powder X-ray diffraction and by electronic absorption and IR spectra. The thermal behavior of the hexahydrate in air was studied. Attempts to prepare the related crystalline compounds M4(NpO2)2(C2O4)3 · nH2O with M = Li or NH4 failed. [ABSTRACT FROM AUTHOR]

New crystalline compounds of the general composition Co(NH3)6[PuO2L]2A · nH2O, where L = CH2(COO)2 and A = HCOO, CH3COO, C2H5COO, and HL, were prepared by adding a small excess of Co(NH3) ions to freshly prepared neutral Pu(V) malonate solutions containing single-charged organic anions. The complexes are sparingly soluble in water and fairly stable when stored in air; they have a similar structure. Previously unknown double Np(V) malonates Co(NH3)6[NpO2L]2A · nH2O, where A = HCOO, CH3COO, and C2H5COO, isostructural with the corresponding Pu(V) compounds, were also prepared. The IR spectra of the new compounds were measured, and their behavior at heating was examined. [ABSTRACT FROM AUTHOR]

Double monooxalates MPuO2C2O4 · nH2O with NH and Cs+ ions in the outer sphere were isolated from weakly acidic aqueous solutions of Pu(V). The unit cell parameters of these compounds were determined. The ammonium salt is isostructural to its neptunyl(V) analog; its structure is characterized by the monodentate cation-cation interaction of plutonyl(V) ions. Cesium plutonyl(V) salt isolated from a solution is not isostructural to the neptunyl(V) compound and is easily dehydrated at room temperature to form tetrahydrate, which transforms to dihydrate at 110°C. The latter compound, according to the IR spectra, can have a network system of cation-cation bonds involving PuO. [ABSTRACT FROM AUTHOR]

Double U(VI) phthalates with NH, K+, and Cs+ ions in the outer sphere were synthesized. The X-ray phase analysis shows that their structures are similar. Single crystals were prepared and the structure of K4[(UO2)4(μ3-O)2(C6H4C2O4)4] ⋅ 3H2O was solved. In the [(UO2)4O2(C6H4C2O4)4]4− anions forming the main structural motif, each bridging oxygen atom μ3-O combines one pentagonal and two hexagonal bipyramids, which, in turn, are combined in centrosymmetrical tetramers. The phthalate ions have coordination capacity equal to 3; each ligand coordinates U(1) in the bidentate fashion via one carboxy group and U(2) in the bidentate fashion to form a planar seven-membered chelate ring. [ABSTRACT FROM AUTHOR]

New crystalline compounds of the composition Co(NH3)6[PuO2L]2A ⋅ nH2O, where L = C3H2O4 and A = NO3, ClO4, Cl, and Br, were obtained by addition of a small excess of Co(NH3) ions to freshly prepared neutral malonate solutions of Pu(V). They are fairly stable in storage in air and isostructural to the corresponding Np(V) compounds. Thermal behavior of the compounds synthesized was studied, and their IR spectra were measured. [ABSTRACT FROM AUTHOR]

Crystalline compounds of the general composition Co(NH3)6PuO2(C2O4)2· nH2O ( n = 2, 3, 5) were isolated from freshly prepared neutral oxalate solutions of Pu(V) by addition of Co(NH3)6 ions. These compounds are fairly stable in storage in air and poorly soluble in water. Previously unknown double Np(V) oxalates Co(NH3+ ions. These compounds are fairly stable in storage in air and poorly soluble in water. Previously unknown double Np(V) oxalates Co(NH3)6NpO2(C2O4O ( n = 2, 5) were also synthesized and studied. All the compounds of Pu(V) and Np(V) of the same composition are mutually isostructural. The behavior of these compounds at heating was studied, and their IR spectra were measured. The optical spectra of new Np(V) compounds were measured. [ABSTRACT FROM AUTHOR]2O ( n = 2, 5) were also synthesized and studied. All the compounds of Pu(V) and Np(V) of the same composition are mutually isostructural. The behavior of these compounds at heating was studied, and their IR spectra were measured. The optical spectra of new Np(V) compounds were measured. [ABSTRACT FROM AUTHOR]

NaPuO2C2O4·3H2O was isolated from a freshly prepared oxalate solution of Pu(VI) by reduction with a stoichiometric amount of hydrazine hydrate. Heating of the compound results in its stepwise dehydration with successive formation of the monohydrate and anhydrous salt. According to powder X-ray patterns, NaPuO2C2O4· nH2O ( n = 3, 4) is isostructural to the corresponding analogs NaNpO2C2O4· nH2O. The unit cell parameters of NaNpO2C2O4·H2O and NaPuO2C2O4· nH2O ( n = 3, 1) were determined. The results of the X-ray analysis and the electronic and IR spectra of the neptunyl(V) and plutonyl(V) crystalline compounds suggest the presence of cation-cation bonds in NaPuO2C2O4· nH2O ( n = 1, 0). [ABSTRACT FROM AUTHOR]

The conditions of synthesis of Pu(V) phthalates by conversion of Pu(VI) into the pentavalent state with addition of H2O2 in the presence of excess of phthalate ions (L) were determined. Subsequent addition of [Co(NH3)6]Cl3 allowed isolation of crystalline [Co(NH3)6][PuO2L2]·2H2O isostructural with [Co(NH3)6][NpO2L2]·2H2O studied previously. The thermal behavior and IR spectra of both compounds were studied. [ABSTRACT FROM AUTHOR]

Neptunium(VI) and plutonium(VI) monophthalates were prepared and characterized. The complexes AnO2 (COO)2C6H4 · 2H2O were isolated from cold solutions, and AnO2 (COO)2C6H4 · 1.33H2O, from hot solutions. NpO2 (COO)2C6H4 b. 2H2O and PuO2 (COO)2C6H4 · 2H2O crystalize in the triclinic and monoclinic systems, respectively. The complexes AnO2(COO)2C6H4 · 1.33H2O are isostructural and crystallize in the rhombohedral system. The thermal behavior of these complexes was studied. Their IR and electronic absorption spectra were recorded. The properties of these complexes were compared to those of known U(VI) monophthalates. [ABSTRACT FROM AUTHOR]

Plutonyl orthosilicate dihydrate (PuO2)2SiO4·2H2O was prepared by a hydrothermal procedure at 180°C. Its powder diffraction pattern (Guinier camera, CuKα1 radiation) was indexed in the tetragonal crystal system: a 6.912(3), c 18.563(3) Å, space group I41/amd. The structure of (PuO2)2SiO4·2H2O is similar to the known structures of (UO2)2SiO4·2H2O and (UO2)2GeO4·2H2O, but differs in the mutual orientation of the chains of coordination polyhedra of actinide atoms (pentagonal bipyramids) sharing common equatorial edges. [ABSTRACT FROM AUTHOR]

The synthesis of crystalline complexes of trivalent lanthanides and americium with N, N-dimethylacetamide (DMAA) and PW12O40 3–anions was described. Their IR and electronic absorption spectra were studied. The structure of the neodymium complex [Nd(DMAA)6PW12O40] was determined using X-ray diffraction analysis. The thermal behavior of the lanthanide complexes was studied. In the 300–400°C temperature interval, even in air, intramolecular partial reduction of the anion occurs to form products which can be characterized as tungsten bronzes. [ABSTRACT FROM AUTHOR]

Preparation conditions and properties of some double Pu(V) malonates MPuO2L · nH2O [L = CH2(COO)2; M = Na, NH4, Cs] were determined. These compounds are isostructural to the corresponding double Np(V) malonates obtained previously. The Pu(V) malonates crystallize in the form of needles from solutions with [L2−] = 0.05–0.3 M containing 0.5–2 M of salts of outer-sphere cations as salting- out agents. Dry crystals are stable for no less than 3 weeks. The IR spectra of these compounds were recorded. Their thermal behavior was studied. The outer-sphere cations presumably form ionic bonds with plutonyl(V) cations, which are weakened with an increase in the cation radius. [ABSTRACT FROM AUTHOR]