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Rare earth metals and rare earth elements, rare metal, main; SC ( Sc ) ( Y ), yttrium, lanthanum, cerium ( La ) ( Ce ), ( Pr ), praseodymium neodymium promethium ( Nd ), ( Pm ) ( Sm ), samarium, europium, gadolinium ( Eu ), ( Gd ) Terbium, dysprosium ( Tb ) ( Dy ), ( Ho ), holmium erbium thulium ( Er ), ( Tm ), ( Yb ), ytterbium lutetium ( Lu ), its atomic number is 21 ( Sc ), 39 ( Y ), 57 ( La ) to 71 ( Lu ). It is the elements of the periodic table III B scandium, yttrium, lanthanum 17 elements collectively, commonly used R or RE.

Physical property.

Rare earth metal gloss between silver and iron. Impurity content on the nature of their great influence, which contained in the literature in the physical properties often have obvious differences. Lanthanum in 6K is a superconductor. The majority of rare earth metal presents paramagnetic gadolinium, at 0 ℃has stronger than iron magnetic iron. Holmium erbium, etc. at low temperatures also presents ferromagnetic. Lanthanum, cerium, samarium, europium with low melting point and high vapor pressure of ytterbium showed a rare earth metal physical property has great difference. Samarium, europium, gadolinium neutron absorption cross section than the widely used for nuclear reactor control material cadmium, boron also. Rare earth metal has plasticity, with SM and Yb is the best. Addition of ytterbium yttrium group rare earths, a cerium group rare earths have higher hardness.

Chemical property.

Rare earth metals have very strong chemical activity. When oxygen, generates high stability of type R2O3 oxide ( R said rare earth metal ). Cerium, terbium, praseodymium also generate CeO2, Pr6O11, PrO2, Tb4O7, TbO2 oxide. Their standard heat of formation and standard free enthalpy minus than calcium, aluminum, magnesium oxide value also. Rare earth metal oxide melting point of over 2000 ℃. Europium atomic radius, nature of most lively, at room temperature is exposed to the air immediately lose metallic luster, soon oxidized into powder. Lanthanum, cerium, praseodymium, neodymium is also easy to oxidation, oxide film formed on the surface. Yttrium, gadolinium lutetium, strong corrosion resistance, can be kept for a long time its metallic luster. Rare earth metal to different rates of reaction with water. Europium and cold violent reaction releases hydrogen. Cerium group rare earth metals at room temperature and water temperature increases slow response, response speed. Yttrium group rare earth metal is relatively stable. Rare earth metals at high temperatures and halogen reaction of +2, +3, +4 valence halide. Anhydrous halides of strong water absorption, easily produced by hydrolysis of ROX ( X represents halogen halogen oxide ) type. Rare earth metal can and boron, carbon, sulfur, phosphorus, nitrogen, hydrogen, reaction of the corresponding compounds. Rare earth metal alloys such as lanthanum nickel alloy ( LaNi5 ) has a large number of hydrogen absorption capacity, is a good material for storage of hydrogen.

Application:

Rare earth metals used in metallurgy, petrochemical, ceramic glass, fluorescent and electronic materials industry. Rare earth metals and their alloys in steelmaking in deoxidation and desulfurization effect, can make both content is reduced to below 0.001%, and change the form of the inclusions, grain refinement, so as to improve the processing properties of steel, improve the strength, toughness, corrosion resistance and oxidation resistance etc.. Rare earth metals and their alloys used in the manufacture of high strength gray cast iron, ductile cast iron and vermicular cast iron, can change the morphology of graphite in cast iron, casting process, improve the mechanical properties of cast iron ( steel, iron ). In the bronze and brass smelting to add a small amount of rare earth can improve the tensile strength, elongation, heat resistance and conductivity of. In casting aluminum silicon alloy containing 1 to 1.5% of the rare earth metal, can improve the high temperature strength. In the aluminum alloy wire adding rare earth metal, could improve the tensile strength and corrosion resistance of. Fe-Cr-Al electrothermal alloy containing 0.3% of rare earth metal, could improve antioxidant capacity, increase the resistivity and high temperature strength. In titanium and its alloys adding rare earth metal can refine grain, reduce the rate of creep, improvement of high temperature corrosion resistance.

Cerium group with mixed rare earth chlorides and rich lanthanum rare earth chloride microspheres prepared by molecular sieve, used in petroleum catalytic cracking process. Rare earth metal and a transition metal compound oxide catalyst for gas purification, can make the carbon monoxide and carbon hydride into carbon dioxide and water. Praseodymium neodymium naphthenate - alkyl aluminium chloride alkyl aluminum three component system catalyst for synthetic rubber.

Rare earth polishing powder used for all kinds of glass device for glass polishing, CeO2 decolorization, while improving the transparency; Pr6O11, Nd2O3 etc for glass coloring; La2O3, Nd2O3, CeO2, used in the manufacture of special glass; in ceramic industry of rare earth can be used in the manufacture of ceramic glaze, refractory materials and ceramic materials. Single high purity rare earth oxides such as Y2O3, Eu2O3, Gd2O3, La2O3, Tb4O7 used for the synthesis of various phosphor, such as color television red fluorescent powder, projection TV white phosphor, phosphor, phosphor for fluorescent lamps, X ray intensifying screen with phosphor and a light conversion fluorescence material. Rare earth metal iodide is used in the manufacture of metal halide lamp, the luminous efficiency is up to 80 ～100 lumens / watt, color temperature is 5500 ～ 6000K, close to the sun, can replace the carbon arc lamp as light source. High pure Y2O3, Nd2O3, Ho2O3, Gd2O3 is a very good laser material.

Preparation of rare earth metal rare earth cobalt alloy, which has high remanence, high coercivity advantages. Yttrium iron garnet ( YIG ) ferrite with high purity of Y2O3 and made of ferric oxide single crystal or polycrystal iron magnetic material. They are used in microwave devices ( such as a YIG device ). Gd2O3 used for the preparation of high purity gadolinium gallium garnet ( GGG ), it is used as a magnetic bubble single crystal substrate. Metal lanthanum and nickel are made of LaNi5 material for storage of hydrogen, hydrogen absorption and desorption speed, per mole of LaNi5 can be stored 6.5 to 6.7 moles of hydrogen. In the atomic energy industry, using europium and gadolinium isotope neutron absorption cross section of large properties, for light water reactors and fast breeder reactor control rod and a neutron absorber. Rare earth elements as trace fertilizer, yield increasing effect on crops. 170Tm released the weak gamma ray, used in the manufacture of portable X ray machine. Flint is rare earth ignition alloy traditional uses, is still the important use of cerium group of rare earth metal.