Dysprosium techniques

The cost of dysprosium metal has dropped in recent years since the development of ion-exchange and solvent extraction techniques, and the discovery of large ore bodies. The metal costs about 300/kg in purities of 99+%. 

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By contrast, the metals have so far found only limited application save for one important use in the field of nondestructive testing. With the proliferation of research reactors over the past decade, neutron radiography has become a practical tool in the aerospace, nuclear and engineering industries, yet without the availability of gadolinium and dysprosium in the form of thin foils, the technique would be severely restricted. 

Dysprosium occurs in apatite, euxenile. gadolinite. and xenotime. All of these minerals also are processed for their yttrium content. With liquid-liquid organic and solid-resin organic ion-exchange techniques, the separation of dysprosium from yttrium is favorable. 

It should be noted that the intermediate state was detected by a magnetic technique in MWO4 [13], and by a magnetooptical one in dysprosium orthoferrite [11]. 

Complexes of lapachol with diverse metals like copper (II), iron (II), iron (III), chromium (III), aluminium (IE), yttrium (El), samarium (IE), gadolinium (IE), and dysprosium (IE) have been investigated [141-144]. Direct electrochemical synthesis of some metal derivatives of lapachol have been carried out [145]. Several P-lapachone hydrazo compounds were synthesized and characterized using spectroscopic techniques including X-ray analyses [146]. Selective aromatic reduction in pyranonaphthoquinones has also been reported [147-148]. 

Sol-gel processes are also suitable for lanthanide oxide formation, as could be shown by the use of Tb(acac)3 and Dy(OBu- )3 in acetylacetone" . Tb203 crack- and pine-hole-free, dense and smooth microstructured buffer layers were produced on nickel tapes by a reel-to-reel continuous sol-gel process. The authors report that the film properties can be strongly influenced by solution components, temperature, time and atmosphere. Nanocrystalline mesoporous dysprosium oxide Dy203 with narrow monomodal pore size distribution can be approached by a combined sol-gel process with a surfactant-assisted templating technique . The spherical Dy203 nanoparticles were formed with aggregations. 

Gamma rays from spent reactor fuel rods were used for the photoreduction of the trivalent lanthanides. A spectral survey of these divalent containing crystals has been presented by McClure and Kiss (16). This photoreduction technique reduces only a minor fraction of the total trivalent concentration, and those divalent ions produced are unstable with respect to heat and/or light. Fong (3) has described these effects using divalent dysprosium as an example. 

Activation analysis is the other field of radiochemical analysis that has become of major importance, particularly neutron activation analysis. In this method nuclear transformations are carried out by irradiation with neutrons. The nature and the intensity of the radiation emitted by the radionuclides formed are characteristic, respectively, of the nature and concentrations of the atoms irradiated. Activation analysis is one of the most sensitive methods, an important tool for the analysis of high-purity materials, and lends itself to automation. The technique was devised by Hevesy, who with Levi in 1936 determined dysprosium in yttrium by measuring the radiation of dysprosium after irradiation with neutrons from a Po-Be neutron source. At the time the nature of the radiation was characterized by half-life, and the only available neutron sources were Po-Be and Ra-Be, which were of low efficiency. Hevesy s paper was not followed up for many years. The importance of activation analysis increased dramatically after the emergence of accelerators and reactors in which almost all elements could be activated. Hevesy received the 1943 Nobel prize in chemistry for work on the use of isotopes as tracers in the study of chemical processes . 

The principle of time-resolved fluorometry has been described in detail elsewhere in this book (refer to the chapter by Biinzli [50]) this chapter oidy concerns clinical applications of time-resolved fluorometric assay (TRFIA) and comparison of this method with other assay techniques. The sensitivity of TRFIA is based on the use of chelates of rare earth metals (lanthanides), e.g., emopium (Eu ), terbium (Tb" ), samarium (Sm" ), and dysprosium (Dy ). Of these, Eu usually provides the highest sensitivity and has therefore been most widely used [6]. The emissimi spectra and decay times of the lanthanides differ from each other, and it has therefore been possible to develop multilabel assays for simultaneous detectiOTi of up to four different antigens [7]. Simultaneous determination of several antigens is especially... 

With radioisotopes now available for many elements, the tracer technique became generally applicable. New variants were developed, such as neutron activation analysis, which was introduced in 1936 for the determination of dysprosium in rare-earth samples (Hevesy and Levi 1936) and subsequently became a widely used technique for sensitive trace analyses, particularly when much larger neutron fluxes became available with the advent of nuclear reactors. Another frequently applied method for trace determination is isotope dilution the species to be determined in the sample is diluted by addition of a known amount of the same species labeled with known specific activity. From the specific activity then resulting and measured, the original quantity of the species is derived, even if only a fi action of the species is finally recovered. The impact on biosciences was revolutionary, when suitable isotopes of key elements in the biosphere were soon discovered (Ti/2 = 10 min) was one of I. Curie and... 

The identification of element 98 was accomplished with a total of only 5,000 atoms (Thompson et al. 1950b). The ion-exchange techniques were also used in the separation and identification of californium. Element 98 was eluted in the expected fraction, and the observed half-life and ot-particle energy of the radioactivity were also in agreement with predictions. It was named after the state of its discovery, although the chemical analog of element 98 was dysprosium (Dy). 

Malkin et al. (1993) have plotted the phase diagrams for solid solutions of thulium, terbium, and dysprosium vanadates RpR i pV04, undergoing the low-temperature structural phase transitions. The pseudospin technique has been used. Considering only the lower set of states of Tm + (non-Kramers doublet), Dy (two close Kramers doublets), and Tb " " (singlet-doublet-singlet) ions in the corresponding vanadates (see table 5), the effective Hamiltonian of the R-ions may be presented in the self-consistent field approximation as follows (see eq. 79) ... 

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