Search Results
Abstract
In the studies of nuclear reactions of heavy ions with heavy nuclei it is often necessary to determine the yields of TPE. Trioctylphosphine oxide (TOPO) has high selectivity with respect to trivalent TPE and rare earths. The possibility of using target or catcher materials as salting-out agents in the extraction of TPE with TOPO from solutions containing DTPA and lactic acid was investigated. The influence of the concentration of Pb, Bi, Cu, Ni, nitric acid and TOPO on the distribution coefficients was established. The advantages of application of the method for the extraction chromatographic separation of TPE and rare earths from the other elements produced in the interaction of ions with heavy elements are shown.
Abstract
Irrigation of rice plants with a solution of rare earth elements increases both the production capacity and the resistance to disease. Assuming that the treated plants remain expendable, the different parts of plants, root stalk and grain, were analyzed by instrumental neutron activation analysis (INAA) and by mass spectrometry after plasma excitation (ICP-MS). About 40 elements were determined. The results showed that the contamination remained in the roots and was absent in rice grains. The analytical distribution of different elements in different parts of both treated and non-treated plants has given some information conceming the possible effect of the rare earth treatment. The performances of the two analytical methods have been compared.
Abstract
Seven rare earth elements (La, Ce, Sm, Eu, Tb, Yb and Lu) in marine shell samples were determined by neutron activation analysis. In order to measure γ-ray using a Ge(Li) detector without serious interference from the intense Compton background from24Na, a simple radiochemical separation was performed by a co-precipitation method with hydrated iron(III) oxide. The chemical yields for shell samples (91–99%) were determined by a re-activation technique for Gd and Yb. The interference from the235U(n, fission) reaction was corrected for determination of La and Ce. The data obtained in this study showed the behavior of rare earth elements in shells during the process of fossilization.
Summary
Rare earth picrate (RE) complexes with L-lysine (Lys) were synthesized and characterized. Elemental analysis (CHN), EDTA titrations and thermogravimetry data suggest a general formula RE(pic)32Lys2H2O, where RE=La-Lu (without Pm) and Y, pic=picrate). IR spectra suggest that Lys is coordinated to the central ion through the nitrogen of the α-amino group. Parameters obtained from the absorption spectrum of the Nd compound indicated that the metal-ligand bonds are essentially electrostatic. Emission spectrum and biexponential behavior of the luminescence decay of the Eu compound suggest the existence of polymeric species. Thermogravimetric/derivative thermogravimetric (TG/DTG) and differential scanning calorimetry (DSC) curves of all complexes are very similar, with five events. The final products are the corresponding rare earth oxides and their X-ray diffraction patterns are identical to the calcinated oxides.</o:p>
Abstract
The conditions of the formation of rare earth(III) 2,5-dihydroxybenzoates have been studied; their compositions and solubilities in water at 293 K have been determined. The IR spectra of the anhydrous complexes with the general formula Ln(C7H5O4)3 have been recorded and their thermal decompositions in static air determined. During heating the anhydrous complexes of Y, Pr-Lu decompose to the oxides Ln2O3, Pr6O11 and Tb4O7 with formation of the intermediate Ln2(C7H4O4)3. The lanthanum complex decomposes to the oxide in three steps forming La2(C7H4O4)3 and La2O2CO3 as intermediates and the Ce(III) complex decomposes directly to CeO2. The properties of rare earth 2,5- and 2,4-dihydroxybenzoates have been compared.
Synthesis and dehydration of double oxalates of rare earths(III) with some monovalent metals
II. Investigations of RbLn(C2O4)2·nH2O
Double oxalates of rare earths(III) and rubidium with the general formulae RbCe(C2O4)2 4.5H2O, RbLn(C2O4)24H2O (Ln=Yb, Lu), RbLn(C2O4)2·3.5H2O (Ln=La, Pr-Dy), and RbLn(C2O4)2·3H2O (Ln=Ho, Er, Tm, Y) were synthesized. They were characterized by chemical analysis, TG, DTG and DSC over the temperature interval 20–500‡C and X-ray powder diffraction examination. At the chosen final temperature (500‡C), either oxide (Ln2O3) or basic carbonate Ln2O2CO3) and Rb2CO3 were obtained, depending on the rare earth(III) element. On the basis of the X-ray diffraction patterns, the isolated compounds can be divided into five isostructural groups.
Abstract
Two easy laboratory methods for preparation of rare-earth orthophosphates (crystallisation from phosphoric acid solution and solid-state reaction with (NH4)2HPO4) were compared on the basis of the products’ properties with a focus on their application as new inorganic pigments. The preparation method has a significant influence on optical properties. The samples prepared by crystallisation have lighter and less rich colour and also change colour more under sunlight irradiation. The surface properties analysed by SEM and presence of a greater amount of phosphoric acid in the crystallisation procedure influence the pH and resistivity of aqueous extract of products and thus their corrosion-inhibition properties. The optical properties of rare-earth orthophosphates and their preliminary corrosion tests show their potential application as highly efficient corrosion-inhibition pigments.
Abstract
The rare earth elements (REEs) content of Kakul phosphate rock (PR) from different localities of the main Hazara deposits of Pakistan were determined using instrumental neutron activation analysis (INAA). 25 phosphorite samples were collected from different phosphorite sites and 6 samples representing different batches from the crushing plant near Kakul Mine. Concentrations of seven REEs (Ce, Eu, La, Lu, Sm, Tb and Yb) were determined in the PR samples. The highest amounts of Heavy and light rare earth elements (HREE and LREE) were quantified in the PR samples collected at the Phosphate Rock Crushing Plant while the lowest amounts of these REEs were measured in the Lambidogi Phosphorite deposit samples. Comparison with global data showed the REEs content of the studied PRs show lower range for all REEs and mostly comparable to the data reported by Israel and Syria. Calculated chondrite ratio for these elements depicts enrichment of LREEs in all phosphorite deposits.
Abstract
A series of rare-earth-doped sodium titanates with the chemical formula R x H y Na4 − (x+y)TiO4·nH2O (where R = Ce3+, Nd3+ and Sm3+) were grown employing solid-state fusion reaction technique. The physico-chemical investigations indicated that the new materials were self engineered into large particles enough to be used in sorption process and having crystalline structures containing localized Na+ ions. Equilibrium studies revealed that an enhancement in sorption efficiency of sodium titanate after rare-earth doping. The neodymium-rich sodium titanate exhibited a better exchange affinity for Cs+ compared to the other studied series. Data on the kinetics of cesium exchange fit well to pseudo-second order and intra-particle diffusion models. In a separate experiment, it was reported that the R-HNaTi series showed responsible sorption affinity toward Ce, Nd and Sm ions in their solution mixture with insignificant selectivity trend which reflects the high stability of titanate matrices.
Abstract
The selectivity of glass type mixed Zr+Ti phosphates with various Ti contents has been investigated toward rare earth metal ions. The kd values were determined by radiotracer technique both in HCl and HNO3 solutions of various concentrations. At room temperature and at pH=4 the following selectivity orders were found: Yb>Tm
Eu>Sm>La (HCl) and Eu>La>Sm>Yb>Tm (HNO3).
