Results 1 - 10 of 24
Results 1 - 10 of 24. Search took: 0.022 seconds
|Sort by: date | relevance|
[en] The separation was studied in the presence of magnesium nitrate and compared with the separation in its absence. As a useful criterion served the expression A/Z (part of Er in precipitate divided by the degree of decomposition). Under all conditions the separation was significantly better in the presence of magnesium nitrate. The method was used to concentrate the heavy yttrium earths (YE) Er, Tm, Yb and Lu from 38 kg to 10 kg YE2O3. (authors)
[en] Thallium, lithium and calcium nitrate ternary system is studied using visual-polythermal technque. The liquidus is formed by three surfaces of crystallization of the initial components. 52.0%TlNO3, 21.0%Ca(NO3)2, 21.0%LiNO3 composition and 124 deg C melting temperature correspond to ternary eutectics. Melts are used to prepare calcium-lithium alloy by means of electrolysis
[en] Using differential scanning calorimeter, the temperatures and enthalpies of Ln(NO3)3x5H2O melting are determined, being equal to 91.28+-0.30 deg C and 46.65+-1.20 kJ/mol, 84.18+-0.44 deg C and 29.97+-1.41 kJ/mol, 66.38+-0.64 deg C and 32.37+-0.94 kJ/mol for Ln=Dy, Ho and Tm respectively
[en] This paper highlights the results of investigations carried out on the extraction of lanthanoids such as Nd(III), Eu(III) and Tm(III) from nitrate solutions into chloroform with 3-phenyl-4-(4-fluorobenzoyl)-5-isoxazolone (HFBPI) in the presence and absence of various crown ethers (CE); 18-crown-6 (18C6), dicyclohexano-18-crown-6 (DC18C6), benzo-18-crown-6 (B18C6) and dibenzo-18-crown-6 (DB18C6). The results demonstrated that these trivalent metal ions were extracted into chloroform as Ln(FBPI)3 with HFBPI alone and as Ln(FBPI)3.CE in the presence of a CE. The equilibrium constants of the above extracted complexes deduced by a non-linear regression analysis were found to increase monotonically with a decrease in ionic radii of these metal ions. The addition of a CE to the metal chelate system significantly improves the extraction efficiency of these metal ions. The complexation strength of trivalent lanthanoids with various CEs follows the order: DC18C6 > 18C6 > B18C6 > DB18C6. Solid complexes of Eu(III) with HFBPI alone and with mixtures of HFBPI and various crown ethers have been isolated and characterised by IR and 1H NMR spectral data to further clarify the nature of the extracted complexes. (orig.)
[en] Spectral investigation of Tm3+ in thulium nitrate has been carried out. For the first time, the second derivative spectrum of this complex has been recorded. The results of a least squares fit of the energy levels and oscillator strengths of the bands are reported in terms of interaction parameters and Judd-Ofelt parameters. Radiative transition probabilities for fluorescence levels 3P0, 1I6, 1D2 and 1G4 of Tm3+ in thulium nitrate are estimated. (author)
[en] As a result of interaction of erbium, thulium and ytterbium nitrates with potassium nitrate new complex compounds K2[(Er(NO3)5]x2H2O; K2[Tm(NO3)5]x2H20); K2[Yb(NO3)5]x2H2O are obtained. The crystals are well soluble in water and spirit. For the first compound the syngony is triclinic, for the rest - monoclinic. IR absorption spectra contain bands of coordinated nitrate group. Interplane distances, relative intensities are determined. Derivatograms of the compounds are recorded. The compounds melt incongruently at the temperatures 85, 75 and 80 deg C respectively. Erbium, thulium and ytterbium oxides are not formed as a result of thermolysis up to 1000 deg C
[en] Carbon-doped aluminum oxide (Al2O3:C) is one of the most used radioluminescence (Rl) materials for fiberoptic dosimetry due to its high efficiency and commercial availability. However, this compound presents the drawback of emitting in the spectral region, where the spurious radioluminescence of fibers is also important. In this work, the radioluminescence response of rare-earth doped Al2O3 samples has been evaluated. The samples were prepared by mixing stoichiometric amounts of aluminum nitrate, urea and dopants with different amounts of terbium, samarium, cerium and thulium nitrates varying from 0 to 0.15 mo 1%. The influence of the different activators on the Rl spectra has been investigated in order to determine the feasibility of using these compounds for Rl fiberoptic dosimetry. (Author)
[en] In this work, α-Al2O3 doped either with Tb3+ or Tm3+ was prepared by combustion synthesis techniques for thermoluminescent (TL) ionizing radiation dosimetry applications. In this method, the reactants (aluminum nitrate, urea and therbium or thulium nitrate) are ignited in a muffle furnace at temperatures as low as 500 oC. This synthesis route is an alternative technique to the conventional fabrication methods of materials based on α-Al2O3 (Czochralsky, Vernuil), where high melting temperatures and reducing atmospheres are required. After combustion, the samples were annealed at temperatures ranging from 1000 to 1400 oC for 4 h in order to obtain the pure α-phase structure and were then irradiated with a Co-60 gamma radiation source. The annealed samples present a well defined TL glow peak with a maximum at approximately 200 oC and linear TL response in the dose range 0.5-5 Gy. It was observed that a 0.1 mol% concentration of Tb3+ or Tm3+ and annealing at 1400 oC optimize the TL sensitivity. The highest sensitivity was found for Tm3+ doped samples which were approximately 25 times more sensitive than Tb3+ doped samples. These results strongly suggest that combustion synthesis is a suitable technique to prepare doped aluminum oxide material and that Tm3+ doped aluminum oxide is a potential material for TL radiation dosimetry.
[en] In the present study, a succession of thulium (Tm)-doped zinc oxide (ZnO) nanostructures samples were prepared by sol-gel method using zinc acetate dihydrate, thulium nitrate pentahydrate and sodium hydroxide species with absolute ethanol as solvent. The X-Ray diffraction (XRD) revealed phase purity (hexagonal Würtzite structure) and high crystalline nature of both Tm3+ doped and undoped ZnO samples. Furthermore, defects mediated levels in the samples were investigated by means of photoluminescence (PL) spectroscopy. Finally, Tm 4d core level was detected in ZnO: 0.5 mol% Tm3+ sample from high resolution X-Ray Photoelectron Spectroscopy (XPS) scan.