Description
The electronic structure of the europium atom Eu I contains 63 electrons that filled 13 shells. The main term is the octet 8 S 7/2 of the configuration 4f 7 6s 2. When the s electron is excited, various terms of the 4f 7 6snl, 4f 7 5dnl and 4f 7 nl 2 configurations arise with high multiplicity (6,8,10) in the LS coupling, which form the spectrum. For the first time, the optical spectrum of the Eu I atom was studied by Russell H. and King A. (1934). Above the first ionization limit (45734.9 cm -1) there are levels of the 4f 7 5dnp configuration, above the second (47404.1 cm -1) there are unclassified levels. To date, the degree of study of Eu I is small; there are many unclassified levels and transitions.
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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 the Englishman William Crookes in 1886. But its properties did not become known immediately. Repeatedly, Crookes and other scientists saw only 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 it a name.
Europium is a metal with atomic number 63. It does not occur alone and is present in nature in rare earth minerals, such as monazite and xenotime. The amount of the chemical element europium in the earth's crust is 1.2 * 10 -4%. For industrial production, the metal is extracted from monazite, since its content in this mineral reaches up to 1%.
The largest deposits of europium are located in Kenya. It is also found in the USA, Brazil, Australia, Scandinavian countries, Russia, Kazakhstan, etc.
Main characteristics
The chemical element europium is a silvery-white metal. Its atomic mass is 151.964 (1) g/mol. It is soft and easily amenable to mechanical action, but only under an inert atmosphere, since 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 (gaining the ability to have 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 neutron contents in the nucleus. The first one is quite stable and is slightly more common in nature. The second isotope is unstable and exhibits 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 is Eu 150 (half-life 36.9 years), and one of the fastest is Eu 152 m3 (half-life 164 nanoseconds).
Chemical properties
The chemical element europium belongs to 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 it is divalent. When heated in an oxygen atmosphere, it forms the compound Eu 2 O 3 in the form of a white-pink powder. When heated slightly, it easily reacts with nitrogen, hydrogen and halogens. Many of its compounds are white with light shades of orange and pink.
Europium (III) cations are obtained by decomposition of solutions of sulfate, oxalate, and nitrate salts. In industry, the metal is produced using carbon or lanthanum by reducing its oxide or electrolysis of its alloy EuCl 3.
Of all the lanthanides, only the emission spectrum of europium(III) ions can be discerned by the human eye. When used to generate laser radiation, the color of its beam is orange.
Application
The chemical element europium has found application 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 to make microcircuits.
The element is used for the production of fluorescent lamps and fluorescent glass. In medicine, it was used to treat some forms of cancer. Its artificial isotope europium 152 serves as an indicator, and the isotope numbered 155 is used for medical diagnostics.
It absorbs thermal neutrons more strongly than other lanthanides, which is very useful in nuclear energy. 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 quantities in the human body. It can also be contained in water, entering it in areas of mineral deposits in which it is included. Industrial production also supplies water with this element.
The effect of the element on the human body and health has not been studied. Trusting the widespread information, it does not pose a particular danger, since its concentrations are usually too low.
Europium has very little toxicity, and its content in water is usually so small that it cannot significantly affect its quality. In fresh and low-salt waters, its amount reaches 1 μg/l, in sea water this figure is 1.1 * 10 -6 mg/l.
Europium
EUROPIUM-and I; m.[lat. Europium] Chemical element (Eu), a silvery-white radioactive metal belonging to the lanthanides (obtained artificially; used in the nuclear and radio engineering industries).
europium(lat. Europium), a chemical element of group III of the periodic table, belongs to the lanthanides. Metal, density 5.245 g/cm 3, t pl 826°C. The name comes from “Europe” (part of the world). Neutron absorber in nuclear reactors, phosphor activator in color TVs.
EUROPIUMEUROPIUM (lat. Europium), Eu (read “europium”), chemical element with atomic number 63, atomic mass 151.96. Consists of two stable isotopes 151 Eu (47.82%) and 153 Eu (52.18%). Configuration of outer electronic layers 4 s 2
p 6
d 10
f 7
5s 2
p 6
6s 2
. The oxidation state in compounds is +3 (valency III), less often +2 (valency II).
Belongs to rare earth elements (cerium subgroup of lanthanides). Located in group III B, in the 6th period of the periodic table. The radius of the neutral atom is 0.202 nm, the radius of the Eu 2+ ion is 0.131 nm, and the Eu 3+ ion is 0.109 nm. Ionization energies 5.664, 11.25, 24.70, 42.65 eV. Electronegativity according to Pauling (cm. PAULING Linus) 1.
History of discovery
Europium was discovered by E. Demarsay in 1886. The element received its name in 1901 after the name of the continent. Europium metal was first obtained in 1937.
Being in nature
The europium content in the earth's crust is 1.310 -4%, in sea water 1.110 -6 mg/l. Part of the monazite minerals (cm. MONAZITE), loparita (cm. LOPARIT), bastnaesite (cm. BASTNESIT) and others.
Receipt
Metallic europium is obtained by the reduction of Eu 2 O 3 in vacuum with lanthanum or carbon, as well as by electrolysis of the EuCl 3 melt.
Physical and chemical properties
Europium is a silver-gray metal. Cubic lattice type a-Fe, A= 0.4582 nm. Melting point 826 °C, boiling point 1559 °C, density 5.245 kg/dm3.
In air, europium is covered with a film of oxides and hydrated carbonates. When heated slightly, it oxidizes quickly. When heated slightly, it reacts with halogens, nitrogen and hydrogen. Reacts with water and mineral acids at room temperature.
Eu 2 O 3 oxide has basic properties; it corresponds to the strong base Eu(OH) 3. The interaction of Eu and Eu 2 O 3, as well as the interaction of trivalent europium oxyhalides with lithium hydride LiH, produces europium (II) oxide EuO. The base Eu(OH) 2 corresponds to this oxide.
Application
It is used as a neutron absorber in nuclear technology, an activator of red phosphors used in color television. 155 Eu - in medical diagnostics.
encyclopedic Dictionary. 2009 .
Synonyms:See what “europium” is in other dictionaries:
- (symbol Eu), a silvery-white metal from the LANTHANIDE series, the softest and most volatile of them. It was first isolated in the form of an oxide in 1896. Europium is mined from the minerals monazite and bastnäsite. Used in the manufacture of color TV screens,... ... Scientific and technical encyclopedic dictionary
- (Europium), Eu, chemical element of group III of the periodic table, atomic number 63, atomic mass 151.96; belongs to rare earth elements; metal. Discovered by the French chemist E. Demarsay in 1901... Modern encyclopedia
- (lat. Europium) Eu, a chemical element of group III of the periodic table, atomic number 63, atomic mass 151.96, belongs to the lanthanides. Metal, density 5.245 g/cm³, melting point 826.C. The name comes from Europe (part of the world). Neutron absorber in... ... Big Encyclopedic Dictionary
- (Europium), Eu chemical. element of group III periodic. systems of elements, at. number 63, at. mass 151.96, part of the lanthanide family. Natural E. consists of isotopes with mass numbers 151 (47.82%) and 153 (52.18%). Electronic configuration of three... ... Physical encyclopedia
Noun, number of synonyms: 3 lanthanide (15) metal (86) element (159) ASIS Dictionary of Synonyms ... Synonym dictionary
europium- Eu Chemical element; belongs to lanthanides; in the form of oxide it is used in nuclear energy as a burnable absorber. [A.S. Goldberg. English-Russian energy dictionary. 2006] Topics energy in general Synonyms Eu EN europium ... Technical Translator's Guide
Europium- (Europium), Eu, chemical element of group III of the periodic table, atomic number 63, atomic mass 151.96; belongs to rare earth elements; metal. Discovered by the French chemist E. Demarsay in 1901. ... Illustrated Encyclopedic Dictionary
63 Samarium ← Europium → Gadolinium ... Wikipedia
- (lat. Europium), chemical. element III gr. period wild system, refers to the lanthanides. Metal, dense 5.245 g/cm3, melting point 826 0C. Name from Europe (part of the world). Neutron absorber in nuclear reactors, activator of phosphors in color. TVs... Natural science. encyclopedic Dictionary
- (prop.) chemical an element from the lanthanide family, symbol Eu (lat. europium); metal. New dictionary of foreign words. by EdwART, 2009. europium [Dictionary of foreign words of the Russian language
Books
- Popular library of chemical elements. In two books. Book 1. Hydrogen - Palladium,. The Popular Chemical Elements Library contains information about all the elements known to mankind. Today there are 107 of them, some of them obtained artificially. How different the properties are...
"Europeum"
Completed by: student of group YaF-42
Zharlgapova Aida
Checked by: Zhumadilov K.Sh.
Astana, 2015
History of discovery
The discovery of europium is associated with the early spectroscopic work of Crookes and Lecoq de Boisbaudran. In 1886, Crookes, while 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 3 g of purified samarium earth from Cleves and carried out its fractional crystallization. After spectroscopy of the resulting fractions, he discovered a number of new lines and designated the supposed new element with the indices Z (epsilon) and Z (zetta). Four years later, Demarsay, as a result of long-term painstaking work to isolate the sought-after element from samarium earth, clearly saw a spectroscopic band of the unknown earth; he gave it the index "E". It was later proven that Lecoq de Boisbaudran's Z(epsilon), and Z(zetta), Demarsay's "E", and the anomalous spectral bands observed by Crookes, belong to the same element, named by Demarsay in 1901 as Europium in honor of the continent of Europe.
EUROPIUM(Europium), Eu - chemical. element of group III periodic. systems of elements, at. number 63, at. mass 151.96, part of the lanthanide family. Natural E. consists of isotopes with mass numbers 151 (47.82%) and 153 (52.18%). Electronic configuration of three ext. shells 4s 2 p 6 d 10 f 7 5s 2 p 6 6s 2. Energy and research ionizations are 5.664, 11.25 and 24.7 eV. Crystalchem. 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 - silvery-white metal, body-centered cubic crystal lattice with lattice constant a= 0.45720 nm. Density 5.245 kg/dm 3, t pl =822 °C, t boil =1597 °C. Heat of fusion 9.2 kJ/mol, heat of evaporation 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 exhibit oxidation states +2 and +3. Natural isotopes of E. have high thermal neutron capture cross sections, so E. is used as an eff. neutron absorber. Eu serves as an activator in decomposition. phosphors based on compounds Y, Zn, etc. Lasers based on ruby activated Eu 3+ produce radiation in the visible region of the spectrum. Of the radionuclides, most What matters are (b - -radioactive 152 Eu (T 1/2 = 13.33 g) and 154 Eu (T 1/2 = 8.8 g), used in g-flaw detection and other purposes.
For the ROSFOND library it was necessary 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 advisable to replace neutron data for a number of isotopes with more modern and complete estimates made in recent 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 FUND-2.2. In this case, we will pay main attention to the results of assessing 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 the work “Thermal Neutron Capture Cross Sections, Resonance Integrals and G-factors”, INDC(NDS)-440, 2003. Radioactive isotopes. There are no complete neutron data sets for the 6 long-lived dysprosium isotopes –145Eu, 146Eu, 147Eu, 148Eu, 149Eu and 150Eu. In the FOND-2.2 library, neutron data for them were taken from EAF-3. In the EAF-2003 version of the library, the data on radioactive neutron capture for the most part remained practically unchanged, but the remaining cross sections were revised taking into account calculations using programs that implement new theoretical models. Of particular note are the long-lived isotopes 152Eu, 154Eu, 155Eu and 156Eu, for which complete sets of neutron data were available. These isotopes are characterized by large radiative capture cross sections and long lifetimes. They are fission products that make a noticeable total contribution to the total absorption cross section of all fission products. Stable isotopes. Data for stable europium isotopes in the FOND-2.2 library were taken from the JENDL-3.3 library with slight data correction (March 1990). The changes concerned the revision of cross sections for threshold reactions. The JEF-3.1 library for Eu-151 uses the estimate made for JEF-2.2 (~ENDF/B-V). For Eu-153, an estimate made for the Japanese neutron data library JENDL-3.2. The neutron data in the JENDL-3.3 library has not been revised since the JENDL-3.2 version (March 1990). ENDF.B-VII (betha 1.2 version, November 2005) adopts the assessment carried out as part of the project to create an international library of fission products. Authors of the assessment: Muhabhab (S.Mughabghab, BNL) - (resonance area); Oblozinsky (P. Oblozinsky, BNL), Rochman (D. Rochman, BNL) and Herman (M. Herman, BNL) - (higher energy region. When analyzing neutron data for individual isotopes, we will proceed from the general information presented above. Europium-152 The Eu-152 isotope is formed by burning out the stable isotope Eu-151. It has three isomeric state. In the ground state - half-life T1\2 = 13.516 years. From which the isotope, with ~70% probability of experiencing 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 being that the probabilities of the decay processes are swapped. The probability of the isomeric transition is negligible. In the second isomeric state (T1\2 =96 min.) undergoes an isomeric transition to the ground state with the emission of a γ-quantum. In FOND-2.2 - estimate by J. Kopecky, D. Nierop, 1992 (EAF-3). In JEFF-3.1 - estimate performed for JENDL-3.2 In JENDL-3.3 - evaluation done for JENDL-3.2 with minor modifications, 1990. In ENDF/B-VII b1.2 - evaluation by R. Wright and JNDC FPND W.G. (2005) for the international fission product library. In the region of allowed resonances (1.E-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). From the information presented in Table 2, it can be seen that both the ENDF/B estimate and the JENDL estimate are consistent 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 assessment adopted by the FUND needs to be revised. Figure 10 shows a comparison of the estimated cross sections for radiative neutron capture in the resonant energy region. From the comparison shown in Figure 10, it can be seen that the ENDF/B estimate significantly expands the range 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.
Application area europium
Europium metal, designation according to Russian standards EvM-1 according to TU 48-2-217-72, ingots, chemical purity 99.9% or more. They belong to rare earth elements (cerium subgroup of lanthanides). Located in group 111 b, in the 6th period of the periodic table, Europium is the lightest of the lanthanides. It is also unstable among 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. Used as a financial instrument. The technical applications of europium are 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 over a wide wavelength spectrum.
2. Nuclear-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. Strontium borate is doped with europium and is used as a phosphor in black light lamps.
7. Europium in medicine: Europium 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. Some special alloys, in particular zirconium-based alloys, are doped with europium, separated from other lanthanides.
Related information.
Story
Being in nature
Place of Birth
Receipt
Metallic europium is obtained by the reduction of 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 europium metal EBM-1 ranged from 800 to 2000 US dollars per kg, and europium oxide with a purity of 99.9% was about 500 dollars per kg.
Physical properties
Europium in its pure form is, like the other lanthanides, a soft, silvery-white metal. It has unusually low density (5.243 g/cm3), melting point (826 °C) and boiling point (1440 °C) compared to its periodic table neighbors gadolinium and samarium. These values contradict the phenomenon of lanthanide compression due to the influence of the electronic configuration of the europium atom 4f 7 6s 2 on its properties. Since the f electron shell 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 in the ytterbium atom. Under normal conditions, europium has a body-centered cubic crystal lattice with a lattice constant of 4.581 Å. When crystallizing under high pressure, europium forms two more modifications of the crystal lattice. Moreover, the sequence of modifications with increasing pressure differs from the sequence in other lanthanides, which is also observed in ytterbium. The first phase transition occurs at pressures above 12.5 GPa, with europium forming 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 a more dense packing. Europium ions embedded in the crystal lattice of some compounds are capable of producing intense fluorescence, with the wavelength of the emitted light depending on the oxidation state of the europium ions. Eu 3+, almost regardless of the substance in whose crystal lattice it is embedded, emits light with wavelengths 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 isotope europium-151 makes up 47.8% of natural europium. It has recently been discovered to have weak alpha radioactivity with a half-life of about 5 x 10 18 years, corresponding to about 1 decay per 2 minutes per kilogram of natural europium. In addition to this natural radioisotope, 35 artificial europium radioisotopes have been created and studied, among which the most stable are 150 Eu (half-life 36.9 years), 152 Eu (13.516 years) and 154 Eu (8.593 years). 8 metastable excited states were also discovered, 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 a typical active metal and reacts with most nonmetals. Europium in the lanthanide group has the maximum reactivity. It oxidizes quickly in air; there is always an oxide film on the metal surface. Store in jars or ampoules under a layer of liquid paraffin or kerosene. When heated in air to a temperature of 180 °C, it ignites and burns to form 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)) )
It is very active and can displace almost all metals from salt solutions. In compounds, like most rare earth elements, it exhibits predominantly an oxidation state of +3; under certain conditions (for example, electrochemical reduction, reduction with zinc amalgam, etc.) an oxidation state of +2 can be obtained. Also, when changing the redox conditions, it is possible to obtain an oxidation state of +2 and +3, which corresponds to an oxide with the chemical formula Eu 3 O 4. With hydrogen, europium forms non-stoichiometric phases in which hydrogen atoms are located in the interstices of the crystal lattice between the europium atoms. Europium dissolves in ammonia to form a blue solution, which is due, as in similar solutions of alkali metals, to the formation of solvated electrons.
