Absorption Spectra of the Octahedral Complex AmBr63- in the Cs2NaLuBr6 Crystal

Absorption spectra of the Cs₂NaLuBr₆:Am³⁺ (5 mol % of ²⁴³Am) were studied in the 450-2500 nm range at temperatures from 300 to 15 K. The spectra exhibited transitions from the ground level ⁷ F ₀ of the Am3+ (f ⁶) ion to the levels belonging to the ground term (⁷ F ₂, ⁷ F ₄, and ⁷ F ₆) and to the levels of the three excited states: ⁵ L ₆, ⁵ G ₂, and ⁵ D ₂. The vibronic pattern analysis for these transitions enabled localization of 17 electronic sublevels of the americium ion in the octahedral complex AmBr₆ ^3-. One sublevel of the electronic level with odd J value (⁷ F ₅) was localized for which the transition from the ground ⁷ F0 level is forbidden in accordance with the Judd-Ofelt theory. The crystal-field paramaters of the complex studied were calculated.     

First Observation of the Cation-Cation Interaction of Actinides in Melts: NpO2 +-UO2 2+ System

Study of the absorption spectra of the NpO ₂ ⁺ ion in a CsCl melt containing 2 M UO ₂ ²⁺ , as well as in K₂UO₂Cl₄ and Cs₂UO₂Cl₄ melts (T = 700°C), allowed the first detection of the cation-cation interaction of actinides in melts. In all the molten salts studied, the cation-cation interaction of NpO ₂ ⁺ and UO ₂ ²⁺ is manifested most clearly (via appearance of an additional band) in the ³ H ₅ ³ H ₄ magnetic-dipole transition of the 5f ² configuration of the NpO₂ ⁺ ion (D _4h symmetry) near 1.6 m: Along with a sharp peak of unbound neptunyl(V) at 1660 nm, there is an equally sharp peak at 1633 nm belonging to the cation-cation complex. The intensity ratio for the peaks at 1633 and 1660 nm increases in the series of melts (UO ₂ ²⁺ in CsCl) < K₂UO₂Cl₄ < Cs₂UO₂Cl₄ by two orders of magnitude.     

Absorption Spectra of Cs2NaNdBr6 Crystal

The electronic and IR absorption spectra of the Cs₂NaNdBr₆ crystal were measured for the first time. By vibronic pattern analysis were localized 32 electronic transitions in the absorption spectra of the octahedral complex NdBr₆ ^3-. Combined analysis of the spectra of neodymium hexachloro and hexabromo complexes provided in a number of complex cases more precise localization of the electronic sublevels of both NdBr₆ ^{3 -} and NdCl₆ ^3-. The crystal-field (CF) parameters were calculated for the Cs₂NaNdBr₆ crystal. It was shown that the CF parameters for the NdBr₆ ^3- complex are by ca. 15% smaller than those for NdCl₆ ^3-.     

Comparative Analysis of the Crystal Field Strengths of Trivalent f Ions in Matrices of Various Symmetries

A comparative analysis of the crystal fields for a number of matrices containing f ions was carried out in terms of the total crystal field strength parameter. A spectrochemical series of systems was constructed, which corresponds to the electronic level splittings for the central ion and shows how the degree of interaction of the f shell with the surrounding varies with the nature of the ligands and outer-sphere cations, as well as with the coordination number, symmetry type, and the metal-ligand interatomic distance.     

Comparative tests of sintered piston rings in a tractor engine

Summary Stand tests of sintered piston rings have been carried out in a tractor engine according to 240- and 480-h programs. The sintered rings were found to give excellent performance; compared with cast iron rings, they showed reduced wear (by a factor of 2–3) and caused less cylinder sleeve wear (by 10–20%). In operation with a set of sintered rings, crankcase oil consumption was reduced by 50%, and several other engine performance parameters showed improvement. In view of these results, it is hoped that sintered piston rings may successfully replace cast iron ones.     

Luminescence Spectra of Am3+ in Cs2NaLuBr6:Am3+ Bromoelpasolite

Luminescence spectra of the cubic crystal of Cs₂NaLuBr₆:Am³⁺ (2.5 mol % ²⁴³Am) were studied in the region of the (² G ₂, ⁵ D ₂) ⁷ F ₀ (460-490 nm) and ⁵ L ₆ ⁷ F ₀ (510-540 nm) transitions in the range from room temperature to 12 K. From the analysis of the vibronic pattern of the spectra, the zero-phonon 0-0 transitions forbidden for the O _h symmetry were localized, and the first data on the splitting sublevels of the actinide element (Am³⁺, 5f ⁶) in the field of the ideal octahedron of the AmBr₆ ^3- type were obtained. It was found that in the wavelength ranges indicated, the crystal studied exhibits a fairly strong self-luminescence due to the -decay energy of ²⁴³Am.     

Failure resistance of structural cast aluminum alloys

Scientific Production Association, Institute of Aviation Materials. Scientific Production Association, Institute of Light Alloys. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 5, pp. 36–38, May, 1991.