Гадолиний химические свойства, назначение, производство
Химические свойства
metal foil, chunks or powder. The powder of gadolinium is highly flammable; incompatible with strong oxidising agents, halogens, acids; and reacts with water or moisture.
Физические свойства
Gadolinium is silvery-white, soft, malleable, and ductile with a metallic luster. It is the secondof what is referred to as the dysprosium, subgroup in the middle of the lanthanide seriesof rare-earths. It tarnishes in air, forming the oxide (Gd2O3) on the surface, which flakes offthe surface, exposing a fresh metal that in turn oxidizes.
Its melting point is 1,313°C, its boiling point is 3,273°C, and its density is 7.90g/cm3.
Изотопы
There are 39 isotopes of gadolinium. Seven of these are stable. They are: Gd-54, which makes up 2.18% of all the gadolinium found in the Earth’s crust; Gd-55,supplying 14.80%; Gd-156, making up 20.47%; Gd-157, constituting 15.56%; and Gd-158, accounting for 24.85%. In addition, there are two isotopes of gadolinium that areradioactive and with such long half-lives that they still exist in the Earth’s crust. They areregarded as stable isotopes along with the other seven. They are Gd-152 (1.08×10+14years), which exists in just 0.20% in abundance, and Gd-160 (1.3×10+21 years), foundin 21.86% abundance.
Происхождение имени
Named for the mineral gadolinite, which was named for the French
chemist Johann Gadolin.
Вхождение
Gadolinium is the 40th most abundant element on Earth and the sixth most abundant ofthe rare-earths found in the Earth’s crust (6.4 ppm). Like many other rare-earths, gadoliniumis found in monazite river sand in India and Brazil and the beach sand of Florida as well asin bastnasite ores in southern California. Similar to other rare-earths, gadolinium is recoveredfrom its minerals by the ion-exchange process. It is also produced by nuclear fission in atomicreactors designed to produce electricity.
Характеристики
Gadolinium, unlike most of the rare earths in the dysprosium subgroup, reacts slowlywith water, releasing hydrogen. It is strongly magnetic at low temperatures. Two of its stableisotopes (Gd-155 and Gd-157) have the greatest ability of all natural elements to absorb thermalneutrons to control the fission chain reaction in nuclear reactors. However, few of theseisotopes are found in the ores of gadolinium.
Использование
Gadolinium’s main use is based on its ability to absorb neutrons, thus making it ideal as aneutron-shielding and neutron-absorbing metal. It is also used as an alloying agent for steel andother metals to make the metals more workable and to be able to withstand low temperatures.
Gadolinium is used in the manufacture of electronics and can be combined with yttriumto make garnets used in microwaves. Gadolinium is used as a catalyst to speed up chemicalreactions, and to activate phosphor compounds in TV screens and cast filaments in electricaldevices. It is also used in high-temperature furnaces. Gadolinium is paramagnetic at normalroom temperatures (weaker than ferromagnetic) and becomes strongly ferromagnetic at verycold temperatures.
Определение
A ductile
malleable silvery element of the lanthanoid
series of metals. It occurs in association
with other lanthanoids. Gadolinium is
used in alloys, magnets, and in the electronics
industry.
Symbol: Gd; m.p. 1313°C; b.p.
3266°C; r.d. 7.9 (25°C); p.n. 64; r.a.m.
157.25.
Опасность
The halogens of gadolinium are very toxic, and gadolinium nitrate is explosive. As withmost rare-earths, care should be taken not to inhale fumes or ingest particles of gadolinium.
Гадолиний препаратная продукция и сырье
сырьё
препарат