неодим

Химические свойства

grey metal ingot

Физические свойства

Neodymium is the third most abundant rare-earth element in the Earth’s crust (24 ppm). Itis reactive with moist air and tarnishes in dry air, forming a coating of Nd₃O₃, an oxide witha blue tinge that flakes away, leaving bare metal that then will continue to oxidize.
Its melting point is 1,021°C, its boiling point is 3,074°C, and its density is 7,01 g/cm³.

Изотопы

There are 47 isotopes of neodymium, seven of which are considered stable.Together the stable isotopes make up the total abundance in the Earth’s crust. Twoof these are radioactive but have such long half-lives that they are considered stablebecause they still exist on Earth. They are Nd-144 (half-life of 2.29×10⁺¹⁵ years) andNd-150 (half-life of 6.8×10⁺¹⁵years). All the other isotopes are synthetic and havehalf-lives ranging from 300 nanoseconds to 3.37 days.

Происхождение имени

Derived from the two Greek words neos and didymos. When combined, they mean “new twin.”

Вхождение

Although neodymium is the 28th most abundant element on Earth, it is third in abundanceof all the rare-earths. It is found in monazite, bastnasite, and allanite ores, where it isremoved by heating with sulfuric acid (H₂SO₄). Its main ore is monazite sand, which is amixture of Ce, La, Th, Nd, Y, and small amounts of other rare-earths. Some monazite sandsare composed of over 50% rare-earths by weight. Like most rare-earths, neodymium can beseparated from other rare-earths by the ion-exchange process.

Характеристики

As an element, neodymium is a soft silver-yellow metal. It is malleable and ductile. It canbe cut with a knife, machined, and formed into rods, sheets, powder, or ingots. Neodymiumcan form trivalent compounds (salts) that exhibit reddish or violet-like colors.
Neodymium reacts with water to form Nd(OHO)₃ and hydrogen (H₂), which can explodeif exposed to a flame or spark. It is shipped and stored in containers of mineral oil.

Использование

Neodymium salts, electronics, alloys, colored glass, (especially in astronomical lenses and lasers), to increase heat resistance of magnesium, metallurgical research, yttrium-garnet laser dope, gas scavenger in iron and steel manufacture

Определение

A toxic silvery element belonging to the lanthanoid series of metals. It occurs in association with other lanthanoids. Neodymium is used in various alloys, as a catalyst, in compound form in carbon-arc searchlights, etc., and in the glass industry. Symbol: Nd; m.p. 1021°C; b.p. 3068°C; r.d. 7.0 (20°C); p.n. 60; r.a.m. 144.24.

Опасность

Many of the compounds (salts) of neodymium are skin irritants and toxic if inhaled oringested. Some are explosive (e.g., neodymium nitrate [Nd(NO₃)₃]).

Профиль безопасности

Human systemic effects by intracerebral route: blood changes. It may be an anticoagulant lanthanoid. Care in handling is advised. Flammable in the form of dust when exposed to heat or flame. Slight explosion hazard in the form of dust when exposed to flame. Can react violently with air, halogens, N2.Violent reaction with phosphorus above 4OOOC. Many of its compounds are poisons.