Story
Being in nature
Place of Birth
Receipt
Europium metal is obtained by reducing Eu 2 O 3 in vacuum with lanthanum or carbon, as well as by electrolysis of the EuCl 3 melt.
Prices
Europium is one of the most expensive lanthanides. In 2014, the price of metallic europium EBM-1 ranged from 800 to 2000 US dollars per kg, and europium oxide with a purity of 99.9% - about 500 dollars per kg.
Physical properties
Europium in its pure form is, like the other lanthanides, a soft, silvery-white metal. It has an unusually low density (5.243 g/cm3), melting point (826 °C) and boiling point (1440 °C) compared to its neighbors in the Periodic Table of the elements gadolinium and samarium. These values contradict the phenomenon of lanthanide contraction due to the influence of the electronic configuration of the europium atom 4f 7 6s 2 on its properties. As electron shell f of the europium atom is half filled, only two electrons are provided for the formation of a metallic bond, the attraction of which to the nucleus is weakened and leads to a significant increase in the radius of the atom. A similar phenomenon is also observed for the ytterbium atom. Under normal conditions, europium has a cubic body-centered crystal lattice with a lattice constant of 4.581 Å. When crystallized under high pressure, europium forms two more modifications of the crystal lattice. In this case, the sequence of modifications with increasing pressure differs from such a sequence in other lanthanides, which is also observed in ytterbium. First phase transition occurs at pressures above 12.5 GPa, while europium forms a hexagonal crystal lattice with parameters a = 2.41 Å and c = 5.45 Å. At pressures above 18 GPa, europium forms a similar hexagonal crystal lattice with denser packing. Europium ions embedded in the crystal lattice of some compounds are capable of producing intense fluorescence, with the wavelength of light emitted dependent on the oxidation state of the europium ions. Eu 3+ practically regardless of the substance in the crystal lattice of which it is embedded, emits light with a wavelength of 613 and 618 nm, which corresponds to an intense red color. On the contrary, the maximum emission of Eu 2+ strongly depends on the structure of the crystal lattice of the host substance and, for example, in the case of barium-magnesium aluminate, the wavelength of the emitted light is 447 nm and is in the blue part of the spectrum, and in the case of strontium aluminate (SrAl 2 O 4 :Eu 2+) wavelength is 520 nm and is in the green part of the visible light spectrum. At a pressure of 80 GPa and a temperature of 1.8 K, europium acquires superconducting properties.
isotopes
Natural europium consists of two isotopes, 151 Eu and 153 Eu, in a ratio of approximately 1:1. Europium-153 has a natural abundance of 52.2% and is stable. The europium-151 isotope makes up 47.8% of natural europium. Recently, its weak alpha radioactivity has been discovered with a half-life of about 5×10 18 years, which corresponds to about 1 decay per 2 minutes in a kilogram of natural europium. In addition to this natural radioisotope, 35 artificial radioisotopes of europium have been created and studied, among which 150 Eu (half-life 36.9 years), 152 Eu (13.516 years) and 154 Eu (8.593 years) are the most stable. Also found are 8 metastable excited states, among which the most stable are 150m Eu (12.8 hours), 152m1 Eu (9.3116 hours) and 152m2 Eu (96 minutes) .
Chemical properties
Europium is typical active metal and reacts with most non-metals. Europium in the lanthanide group has the highest reactivity. It quickly oxidizes in air, there is always an oxide film on the metal surface. Stored in jars or ampoules under a layer of liquid paraffin or in kerosene. When heated in air to a temperature of 180 ° C, it ignites and burns with the formation of europium (III) oxide.
4 E u + 3 O 2 ⟶ 2 E u 2 O 3 (\displaystyle \mathrm (4\ Eu+3\ O_(2)\longrightarrow 2\ Eu_(2)O_(3)) )
Very active, can displace almost all metals from salt solutions. In compounds, like most rare earth elements, it predominantly exhibits an oxidation state of +3; under certain conditions (for example, electrochemical reduction, zinc amalgam reduction, etc.), an oxidation state of +2 can be obtained. Also, when redox conditions change, it is possible to obtain an oxidation state of +2 and +3, which corresponds to oxide with chemical formula Eu 3 O 4 . Europium forms nonstoichiometric phases with hydrogen, in which the hydrogen atoms are located in the gaps of the crystal lattice between the europium atoms. Europium dissolves in ammonia to form a solution of blue color, which is due, as in similar solutions of alkali metals, to the formation of solvated electrons.
Europium is a chemical element in the periodic table. It is used in energy, medicine and electronics and is the most expensive representative of the lanthanides. What are the properties and characteristics of europium?
Element 63
The chemical element europium was first discovered by Englishman William Crookes in 1886. But its properties became known far from immediately. Repeatedly, Crookes and other scientists saw only the spectral lines of a substance unknown to them. Its discovery is attributed to the Frenchman Eugene Demarce, who not only discovered the element, but also isolated it from the mineral, described it and gave the name.
Europium is a metal with an atomic number of 63. It does not occur in independent form and is present in nature as part of rare earth minerals, for example, monazite and xenotime. The amount of the chemical element europium in earth's crust is 1.2 * 10 -4%. For industrial production, metal is mined from monazite, since its content in this mineral reaches 1%.
The largest deposits of europium are in Kenya. It is also found in the USA, Brazil, Australia, Scandinavian countries, Russia, Kazakhstan, etc.
Main characteristics
Chemical element europium is a silver-white metal. His atomic mass is 151.964 (1) g/mol. It is soft and easily amenable to mechanical action, but only with an inert atmosphere, as it is a fairly active substance.
The melting point of the metal is 826 degrees Celsius, europium boils at a temperature of 1529 degrees. It can become superconducting (acquires the ability to zero electrical resistance) at a pressure of 80 GPa and a temperature of -271.35 Celsius (1.8 K).
There are two natural isotopes of the element europium 153 and europium 151 with different numbers of neutrons in the nucleus. The first is quite stable and is slightly more common in nature. The second isotope is unstable and has alpha decay. The period of the chemical element europium 151 is 5×10 18 years. In addition to these isotopes, there are 35 more artificial ones. The longest has Eu 150 (half-life 36.9 years), and one of the fastest - Eu 152 m3 (half-life 164 nanoseconds).
Chemical properties
The chemical element europium is in the lanthanide group, along with Lanthanum, Cerium, Gadolinium, Promethium and others. He is the lightest and most active of all his "classmates". Europium quickly reacts with air, oxidizing and becoming covered with a film. Because of this, it is usually stored in paraffin or kerosene in special containers and flasks.
Europium is also active in other reactions. In compounds, it is usually trivalent, but sometimes divalent. When heated in an oxygen atmosphere, it forms the compound Eu 2 O 3 in the form of a white-pink powder. With a slight heating, it easily reacts with nitrogen, hydrogen and halogens. Many of its compounds are white with lighter shades of orange and pink.
Europium (III) cations are obtained by decomposition of solutions of salts of sulfate, oxalate, nitrate. In industry, the metal is obtained using carbon or lanthanum by reducing its oxide or by electrolysis of its EuCl 3 alloy.
Of all the lanthanides, only the emission spectrum of europium (III) ions can be perceptible to the human eye. When used to generate laser radiation, the color of its beam is orange.
Application
The use of the chemical element europium found in the field of electronics. In color television, it is used to activate red or blue phosphors. Its combination with silicon EuSi 2 forms thin films and is used for the manufacture of microcircuits.
The element is used for the production of fluorescent lamps and fluorescent glass. In medicine, it has been used to treat certain forms of cancer. Its artificial isotope europium 152 serves as an indicator, and the isotope number 155 is used for medical diagnostics.
It absorbs thermal neutrons more than other lanthanides, which is very useful in nuclear power engineering. For these purposes, its oxide, a compound with boric acid (europium borate) and a binary compound with boron (europium hexaboride) are used. The element is also used in atomic hydrogen energy during the thermochemical decomposition of water.
Harm and impact on humans
Europium is found in small amounts in the human body. It can also be contained in water, getting into it in the areas of mineral deposits in which it is included. Industrial production also supplies water with this element.
The effect of the element on the body and human health has not been studied. Trusting the widespread information, it does not pose a particular danger, since its concentrations are usually too small.
Europium has very little toxicity, and its content in water is usually so insignificant that it cannot significantly affect its quality. In fresh and low-salt waters, its amount reaches 1 μg / l, sea water this figure is 1.1 * 10 -6 mg / l.
Europeum
Completed: student of the YaF-42 group
Zharlgapova Aida
Checked by: Zhumadilov K.Sh.
Astana, 2015
Discovery history
The discovery of europium is associated with the early spectroscopic work of Crookes and Lecoq de Boisbaudran. In 1886, Crookes, studying the phosphorescence spectrum of the mineral samarskite, discovered a band in the wavelength region of 609 A. He observed the same band when analyzing a mixture of ytterbium and samarium earths. Crookes did not give a name to the suspected element and temporarily designated it with the index Y. In 1892, Lecoq de Boisbaudran received from Cleve 3 g of purified samarium earth and produced its fractional crystallization. After spectroscopy of the obtained fractions, he discovered a number of new lines and designated the proposed new element with the indices Z (epsilon) and Z (zetta). Four years later, Demarsay, as a result of long painstaking work on isolating the desired element from samarium earth, clearly saw the spectroscopic band of the unknown earth; he gave her the index "E". It was later proved that Z(epsilon) and Z(zetta) by Lecoq de Boisbaudran, Demarsay's "E" and the anomalous bands of the spectrum observed by Crookes refer to the same element, which Demarsay named in 1901 as europium (Europium) in honor of the European continent.
EUROPIUM(Europium), Eu - chem. element Group III periodic systems of elements, at. number 63, at. mass 151.96, is a member of the lanthanide family. Natural E. consists of isotopes with mass numbers 151 (47.82%) and 153 (52.18%). Electronic configuration three ext. shells 4s 2 p 6 d 10 f 7 5s 2 p 6 6s 2 . The energies are followed. ionizations are 5.664, 11.25 and 24.7 eV. Crystallohim. the radius of the Eu atom is 0.202 nm (the largest among the lanthanides), the radius of the Eu 3+ ion is 0.097 nm. The electronegativity value is 1.01. In free form - silver-white metal, body-centered cubic crystal lattice with constant lattice a= 0.45720 nm. Density 5.245 kg / dm 3, t pl \u003d 822 ° С, t kip \u003d 1597 ° С. Heat of fusion 9.2 kJ/mol, heat of vaporization 146 kJ/mol, sp. heat capacity 27.6 J/mol.K, sp. resistance 8.13.10 -5 Ohm.cm (at 25 °C). Paramagnetic, magnetic susceptibility 22.10 -8 . In chem. compounds exhibits oxidation states +2 and +3. Natural isotopes E. have high thermal neutron capture cross sections, so E. is used as an eff. neutron absorber. Eu serves as an activator in decomp. phosphors based on compounds Y, Zn, etc. Lasers based on ruby activated by Eu 3+ give radiation in the visible region of the spectrum. Of the radionuclides, most (b - radioactive 152 Eu (T 1/2 \u003d 13.33 g) and 154 Eu (T 1/2 \u003d 8.8 g) used in g-defectoscopy and other purposes are of importance.
For the ROSFOND library, it was required to select neutron data for 12 stable and long-lived isotopes of europium. Data for all these isotopes are contained in the FOND-2.2 library. However, as will be seen below, it would be expedient to replace the neutron data for a number of isotopes with more modern and complete estimates made in last years. Let us consider the results of the re-evaluation of data for europium isotopes carried out in recent years in comparison with the estimates contained in FOND-2.2. In this case, the main attention will be paid to the results of estimating the capture cross section. All experimental data used in comparison with the estimated cross sections were taken from the EXFOR-CINDA database (version 1.81, June 2005). Recommended Muhabhab values are given according to “Thermal Neutron Capture Cross Sections, Resonance Integrals and G-factors”, INDC(NDS)-440, 2003. Radioactive Isotopes. For the 6 long-lived dysprosium isotopes –145Eu, 146Eu, 147Eu, 148Eu, 149Eu, and 150Eu, there are no complete neutron data sets. In the FOND-2.2 library, the neutron data for them were taken from EAF-3. In the version of the EAF-2003 library, the data on radioactive neutron capture for the most part remained practically unchanged, however, the remaining cross sections were revised taking into account calculations using programs that implement new theoretical models. Separately, the long-lived isotopes 152Eu, 154Eu, 155Eu, and 156Eu, for which complete sets of neutron data were available, should be noted. These isotopes are characterized by large radiative capture cross sections and long lifetimes. They are fission products that make an appreciable total contribution to the total absorption cross section of all fission products. stable isotopes. The data for europium stable isotopes in the FOND-2.2 library were taken from the JENDL-3.3 library with minor data corrections (March 1990). The changes concerned the revision of cross sections for threshold reactions. The JEF-3.1 library for Eu-151 uses the evaluation done for JEF-2.2 (~ENDF/B-V). For Eu-153, an estimate made for the JENDL-3.2 Japanese Neutron Data Library. In JENDL-3.3, neutron data has not been revised since JENDL-3.2 (March 1990). ENDF.B-VII (betha 1.2 version, November 2005) adopted an assessment made by the International Fission Products Library project. The authors of the assessment: Muhabhab (S.Mughabghab, BNL) - (resonant region); Oblozhinsky (P. Oblozinsky, BNL), Rohman (D. Rochman, BNL) and Herman (M. Herman, BNL) - (higher energy region. When analyzing neutron data for individual isotopes, we will proceed from that general information which is stated above. Europium-152 The isotope Eu-152 is formed by burning out the stable isotope Eu-151. It has three isomeric states. In the ground state - half-life T1 \ 2 = 13.516 years. From which the isotope, with ~ 70% probability, undergoing β-decay, turns into a stable isotope Gd-150 (α-active), and with ~ 30% probability, as a result of positron decay, turns into Sm-152. In the first isomeric state, the half-life is 9.31 hours. The decay chain is similar to the ground state, with the only difference that the probabilities of the decay processes are reversed. The probability of an isomeric transition is negligible. In the second isomeric state (T1\2=96 min.), it experiences an isomeric transition to the ground state with the emission of a γ-quantum. In FUND-2.2 - assessment by J.Kopecky, D.Nierop, 1992 (EAF-3). In JEFF-3.1, an evaluation performed for JENDL-3.2. In JENDL-3.3, evaluation performed for JENDL-3.2 with minor changes, 1990. In ENDF/B-VII b1.2, evaluation by R. Wright and JNDC FPND W.G. (2005) for the International Fission Products Library. In the region of allowed resonances (1.Е-5 eV - 62.07 eV), the ENDF/B estimate was used, above, the JENDL-3.3 estimate. Some characteristics for the resonant energy region are given in Table 2. They were obtained using the INTER program from the ENDF UTILITY CODES software package (release 6.13, July 2002). It can be seen from the information in Table 2 that both the ENDF/B estimate and the JENDL estimate agree with the experimental value of the capture cross section. Note that there is a strong discrepancy between the value of the resonance integral recommended by Muhabhab (BNL-325, 1981) and the values obtained from the estimated cross sections. It is also clear from the tabular data that the estimate accepted by the FUND needs to be revised. Figure 10 compares the estimated cross sections for neutron radiative capture in the resonant energy region. The comparison in Figure 10 shows that the ENDF/B estimate significantly expands the region of allowed resonances. When describing resonances in the region of 2 eV, the ENDF/B estimate is higher than the JENDL estimate, which causes small discrepancies in the value of the resonance integral between these estimates.
Scope of europium
Europium metal, designation according to Russian standards EvM-1 according to that 48-2-217-72, ingots, chemical purity 99.9% or more. They belong to the rare earth elements (the cerium subgroup of the lanthanides). Located in group 111 in, in period 6 periodic system Europium is the lightest of the lanthanides. it is unstable among the Saami rare earth elements - in the presence of atmospheric oxygen and moisture, it quickly oxidizes (corrodes). Europium is the most active and one of the most expensive lanthanides. It is used as a financial instrument. The technical application of europium is as follows:
1. Nuclear power: europium is used as a neutron absorber in nuclear reactors, the most active in terms of neutron capture is europium-151. this provides highly effective protection against hard radiation in a wide range of wavelengths.
2. Atomic hydrogen Energy: Europium oxide is used in the thermochemical decomposition of water in nuclear-hydrogen energy (Europium-strontium-iodide cycle).
3. Laser materials: Europium ions are used to generate laser radiation in the visible region of the spectrum (orange rays), so europium oxide is used to create solid-state, liquid lasers.。
4. Electronics: Europium is a dopant in samarium monosulfide (thermoelectric generators), and also as an alloying component for the synthesis of diamond-like (superhard) carbon nitride. Europium silicide in the form of thin films is used in integrated microelectronics.
5. Europium monoxide is used in the form of thin films as magnetic semiconductor materials for rapidly developing functional electronics, and in particular MIS - electronics
6. Phosphors: Europium tungstate is a phosphor used in microelectronics and television. Europium-doped strontium borate is used as a phosphor in black light lamps.
7. Europium in medicine: Europium and cations are successfully used in medicine as fluorescent probes. Radioactive isotopes of Europium are used in the treatment of certain forms of cancer.
8. Other uses of europium: photosensitive compounds of europium with bromine, chlorine and iodine are being intensively studied. Europium-154 has a high heat release rate during radioactive decay and has been proposed as a fuel in radioisotope energy sources. Europium, separated from other lanthanides, is alloyed with some special alloys, in particular alloys based on zirconium.
Similar information.
Europium - 63
Europium (Eu) is a rare earth metal, atomic number 63, atomic mass 152.0, melting point 826°C, density 5.166 g/cm3.
The name of the element, europium, which was discovered in its pure form in 1901, needs no explanation of the origin of this name. In nature, there are no minerals with a sufficiently high content of europium, it is highly dispersed (monazite sand contains 0.002% of this element), but at the same time, europium in the earth's crust is twice as much as silver, and gold - 250 times.
It was possible to isolate europium compounds from minerals containing mixtures of salts of various lanthanides only in 1940, after lengthy studies. The raw materials for obtaining europium are minerals and technogenic compounds: loparite (0.08%), eudialyte (0.95%), Khibiny apatite (0.7%), phosphogypsum from Khibiny apatite (0.6%), Tomtor natural concentrate ( 0.6%) (the percentage is indicated from the total content in the raw material).
europium rare earth metal
Europium is a silvery-white metal, the lightest of the lanthanides, its density is 1.5 times less than that of iron. This metal is soft, similar in hardness to lead, easily processed by pressure in an inert atmosphere.
Europium reacts with hydrogen and water, interacts with acids, but does not react with alkalis. It oxidizes well in air, with the formation of an oxide film.
Of the radioactive isotopes of europium, europium-155 has been well studied (half-life of about two years).
RECEIVING.
To isolate europium from a mixture of REMs in minerals, chromatography and extraction methods are used to obtain either calcium fluoride or magnesium europium fluoride, from which europium metal is then obtained.
Europium in metallic form is also obtained by reducing its oxide Eu2O3, in vacuum with lanthanum or carbon, or by electrolysis of a melt of europium chloride EuCl3.
APPLICATION.
Europium is used relatively limitedly, due to its high cost, but in innovative technologies.
Nuclear power. The nuclei of europium atoms capture neutrons well, which is used in nuclear power engineering to use europium as a neutron absorber in regulating nuclear processes.
Lasers. Europium oxide is used to create solid-state and liquid lasers that generate laser radiation in the visible region of the spectrum (orange rays).
Astronomy. Flash phosphors containing negligible fractions of a percent of europium are used in astronomy in the infrared part of the spectrum, to study the radiation of stars and nebulae.
Electronics. Modern microchips and memory devices are created, among other things, using europium.
Alloys and ceramics. Europium in ceramics is used to create superconductors, and its alloys are used in ferrous and non-ferrous metallurgy.
Hydrogen energy. To obtain thermal energy by the method of thermo-chemical decomposition of water, europium oxide is used.
Others. Europium isotopes are used in medical diagnostics, when creating filters in environmental devices, europium began to be used significantly for defense purposes. In addition, the use of europium is under active study.
Defectoscopy. The radioactive isotope of europium is used in light portable devices for transillumination and quality control of thin-walled metal vessels. Gamma flaw detection based on europium isotopes is much more sensitive than flaw detection based on cesium and cobalt isotopes. For the analysis of minerals containing europium, europium salts are used that fluoresce from ultraviolet radiation. In this way, negligible fractions of europium are found in the studied mineral.
Description
The electronic structure of the europium atom Eu I contains 63 electrons, which filled 13 shells. The base term is the octet 8 S 7/2 of the configuration 4f 7 6s 2 . When an s electron is excited, various terms of the 4f 7 6snl, 4f 7 5dnl, and 4f 7 nl 2 configurations arise with a high multiplicity (6,8,10) in the LS bond, which form the spectrum. The optical spectrum of the Eu I atom was first studied by Russell H. and King A. (1934). Above the first ionization limit (45734.9 cm -1) there are configuration levels 4f 7 5dnp, above the second (47404.1 cm -1) - unclassified levels. To date, the degree of knowledge of Eu I is low, there are many unclassified levels and transitions.
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