The accessible divalency of europium has always made it one of the easiest lanthanides to extract and purify, even when present, as it usually is, in low concentration. See also europium compounds. Template:Isotopes of europium Naturally occurring europium is composed of 2 stable isotopes , Eu and Eu, with Eu being the most abundant All of the remaining radioactive isotopes have half-lives that are less than 4.
The primary decay mode before the most abundant stable isotope, Eu, is electron capture , and the primary mode after is beta minus decay. The primary decay products before Eu are isotopes of samarium Sm and the primary products after are isotopes of gadolinium Gd.
Europium is produced by nuclear fission, but as it is near the top of the mass range for fission products , the fission product yields of europium isotopes are low. Like other lanthanides, many isotopes, especially isotopes with odd mass numbers and neutron-poor isotopes like Eu, have high cross sections for neutron capture , often high enough to be neutron poisons.
Most will be transmuted to nonradioactive and nonabsorptive Gadolinium by the end of fuel burnup. Overall, europium is overshadowed by Cs and Sr as a radiation hazard, and by samarium and others as a neutron poison. The toxicity of europium compounds has not been fully investigated, but there are no clear indications that europium is highly toxic compared to other heavy metals.
The metal dust presents a fire and explosion hazard. Europium has no known biological role. Europium metal is available commercially so it is not normally necessary to make it in the laboratory, which is just as well as it is difficult to isolate as the pure metal. This is largely because of the way it is found in nature. The lanthanoids are found in nature in a number of minerals. The most important are xenotime, monazite, and bastnaesite. The first two are orthophosphate minerals LnPO4 Ln deonotes a mixture of all the lanthanoids except promethium which is vanishingly rare and the third is a fluoride carbonate LnCO3F.
Lanthanoids with even atomic numbers are more common. The most comon lanthanoids in these minerals are, in order, cerium, lanthanum, neodymium, and praseodymium.
Monazite also contains thorium and ytrrium which makes handling difficult since thorium and its decomposition products are radioactive.
For many purposes it is not particularly necessary to separate the metals, but if separation into individual metals is required, the process is complex. Initially, the metals are extracted as salts from the ores by extraction with sulphuric acid H2SO4 , hydrochloric acid HCl , and sodium hydroxide NaOH.
Modern purification techniques for these lanthanoid salt mixtures are ingenious and involve selective complexation techniques, solvent extractions, and ion exchange chromatography. Pure europium is available through the electrolysis of a mixture of molten EuCl3 and NaCl or CaCl2 in a graphite cell which acts as cathode using graphite as anode.
The other product is chlorine gas. Categories: Chemical elements Lanthanides. The physical and chemical properties of the rare earths in silica glass present particular interest, but the difficulty in the incorporation of high concentrations of rare earths attached covalently to the silicon network is still a challenge.
The sol-gel method has been used to prepare materials in the form of powders, films, fibers and monolith, which are based on different metals The intrinsic characteristics of the method, that are to work at room temperature and the ability to mix different chemicals at the molecular level 13 , make this method well adapted to prepare organic containing materials.
The interest in the incorporation of luminescent species encompasses a wide variety applications such as in lasers, chemical sensors and waveguides 14, The rare earths are used as probes in the sol-gel method due to their sensibility to changes in the surroundings.
The Europium III ion is utilized to monitor the synthesis of glass by the sol-gel method 16 and there is a great interest in modifying the surroundings of the ions in order to reduce the loss in energy of the excited states via non-radiative mechanism In this work, silica was prepared with its surface modified by sol-gel method and studied through the incorporation of Europium III compounds in two different ways. In the second the solid silica modified was obtained firstly and then the Eu species were incorporated on silica surface.
The same systems were also studied in the absence of the modifier agent for comparison purposes. These materials were studied by luminescence, infrared spectroscopies and termogravimetric analysis.
The Eu bpy Cl 3 compound was prepared as described in literature The acetic acid was used as catalyst. All the synthesis were carried out in ethanolic medium.
The luminescence data were obtained with a Spex Fluorolog II spectrofluorometer at room temperature. Samples were placed in a capillary tube I. The emission was collected at Luminescence lifetime measurements were performed with a Spex D model phosphorimeter. The presence of the organic groups in the silica was confirmed through thermogravimetric analysis and IR spectra. We can observe that the samples prepared without the modifier agent APTS present a larger amount of absorbed water.
Comparing the samples that contain the agent APTS, we noticed that the amount of water absorbed is smaller than the samples obtained by the method 2. This can be an indicative that the presence of the europium compounds in the preparation of the silica affects the condensation degree, affecting the amount of absorbed water absorbed in the silica. Chapter 3. Fontenot, Kamala N. Bhat, William A. Hollerman and Mohan D. Chapter 4. Pearton, F. Ren and J. Chapter 5.
Kulshreshtha and V. Chapter 6. Rare earth: China's new gold rush. Malaysia protest over rare earths. Rare earth elements are chemically similar and are sometimes used in similar ways. Yttrium is used in the process of generating colour displays on devices such as television screens. Yttrium, terbium, europium.
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