- Room temperature reaction between uranyl nitrate hexahydrate and rubidium nitrate and polymerisation during denitration of rubidium uranyl nitrate at elevated temperatures
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The interaction between uranyl nitrate hexahydrate (UNH) and rubidium nitrate in solid state at elevated temperatures has been studied for several compositions using simultaneous thermal analysis techniques (TG-DTA-EGA), X-ray diffraction and IR spectral measurements. The formation of rubidium uranyl nitrate has been observed in rubidium nitrate rich mixtures even at ambient temperature during mixing of the two nitrates in solid state. The reaction at room temperature was incomplete in mixtures containing higher than 30 mol% uranyl nitrate hexahydrate. Thermal and XRD data on equimolar mixture indicate complete dehydration of uranyl nitrate hexahydrate by 300 °C to form rubidium uranyl nitrate, Rb[UO2(NO3)3], which decomposes on further heating to the polymerised structures, Rb 2[(UO2NO3)2(O)2] and Rb4[(UO2)3(O)4(NO3) 2] above 360 °C and 460 °C, respectively. Rb 4[(UO2)3(O)4(NO3) 2] reacts with UO3 above 550 °C to form rubidium diuranate, Rb2U2O7, when the initial nitrate mixture is prepared from compositions containing UNH at 50 mol% or lower levels. In the case of initial nitrate mixtures containing a higher amount of UNH, however, Rb2U4O13 and U3O 8 are formed above 550 °C.
- Kalekar, Bhupesh B.,Rajagopalan,Ravindran
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- Synthesis and spectroscopic properties of RbLa1-xEuxP4O12 nanocrystals
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The cubic and monoclinic RbLa1-xEuxP4O12 nanocrystalline phosphors were synthesized using co-precipitation method. The influence of the dopant concentration on the structural and luminescent properties was inves
- Marciniak,Stefanski,Tomala,Hreniak,Strek
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- Synthesis of rubidium fluorophosphatozirconates in the ZrO 2-H3PO4-RbF-H2O system and their luminescent properties
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Rubidium fluorophosphatozirconates (RFPZs) were synthesized along sections of the ZrO2-H3PO4-RbF-H2O system where PO 4 3- /Zr = 1-2 (mol/mol) and RbF/Zr = 1-5 (mol/mol) and the initial solution contains 2-5 wt % ZrO2. The following RFPZs have been isolated for the first time: RbZrF2PO 4 ? 0.5H2O, Rb3H3Zr 3F3(PO4)5, and RbZr 3F4(PO4)3 ? 1.5H2O. Their formation fields were determined. The compounds were characterized using powder X-ray diffraction, crystal-optical analysis, chemical analysis, electron probe microanalysis, thermal analysis, and IR spectroscopy. Luminescent properties of the compounds were measured. All RFPZs are orthophosphates, have high thermal durability, and X-ray luminescence (XRL). Rb3H 3Zr3F3(PO4)5 has the highest XRL intensity.
- Godneva,Motov,Boroznovskaya,Kuznetsov
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- Phase equilibria and critical phenomena in the rubidium nitrate-water-acetonitrile system
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Phase equilibria and critical phenomena were studied from -5 to 120°C in the rubidium nitrate-water-acetonitrile system, in which the liquid binary subsystem is characterized by liquid-liquid phase separation with an upper critical solution point (UCSP), using a visual polythermal method. We found that rubidium nitrate has a salting out effect on water-acetonitrile solutions and causes them to demix at any temperature in the specified range. Acetonitrile distribution coefficients between aqueous and organic monotectic phases were calculated for various temperatures. The minimum value was observed for 20.0°C. Six isothermal phase diagrams of the system were plotted to verify a fragment of the global scheme of the topological transformation of phase diagrams for salt-binary solvent ternary systems with salting out. The salting out effects of potassium, rubidium, and cesium nitrates on water-acetonitrile mixtures were comparatively analyzed.
- Cherkasov,Il'in
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- Synthesis and crystal structure of alkali metal and ammonium nitratocuprates(II): M3[Cu(NO3)4](NO3) (M = K, NH4, Rb) and Cs2[Cu(NO3)4]
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Blue crystals of metal nitratocuprates(II), M3[Cu(NO3)4](NO3) (M = K (I), NH4 (II), Rb (III)) and Cs2[Cu(NO3)4] (IV) were synthesized from Cu(NO3)2 · 3 H2O and MNO3 by heating at 100-140°C during 3-12 h. X-ray single crystal structures for isotypic I and II reveal the presence of the [Cu(NO3)4]2- and NO3- anions and M+ cations. Structure IV contains [Cu(NO3)4]2- and Cs+. In structures I, II, and IV, Cu atoms have a square-planar coordination [CuO4] with short Cu-O distances of 1.92-2.00 A?, the oxygen atoms belonging to four different NO3 groups. Each coordinated NO3 group is a nonsymmetrical bidentate ligand with the second, longer Cu-O distance from 2.38 to 2.74 A?. Rubidium derivative III was shown to be isotypic to I on the basis of unit cell dimensions and symmetry. Eight-coordinate metal(II) environment in tetranitrates is compared for transition metals with different electronic configurations.
- Morozov,Fedorova,Troyanov
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p. 1543 - 1547
(2008/10/09)
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