How many rare earth elements are there?
Rare Earth elements are the general name of the Lanthanide Rare Earth Group, it contains 17 elements including scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu). The term “rare earth” has been used since the 18th century, because of technical constraints, rare elements were hardly separated, obtained oxide does not melt, neither insoluble in water, its appearance resembles “soil”, and called rare earth.
How many types of rare earth?
Rare Earth elements are divided into “light rare earth elements” and “heavy rare earth elements” :
“Light rare earth” refer to SC, Y, La, CE, PR, ND, PM, SM, EU with small atomic numbers.
“Heavy rare earth elements” refer to Gd, TB, Dy, Ho, Er, TM, Yb, Lu with relatively large atomic numbers.
What are ‘rare earth’ used for?
Lanthanum is widely used in piezoelectric materials, electrothermal materials, thermoelectric materials, magnetoresistance materials, luminescent materials, hydrogen storage materials, optical glass, laser materials, all kinds of alloy materials, etc. It is also used as a catalyst for the preparation of many organic chemical products, light conversion agricultural films.
As a glass additive, cerium can absorb ultraviolet and infrared rays, it has been widely used in automobile glass. Not only can prevent ultraviolet rays, but it also can reduce the temperature in the car, thus saving electricity for air conditioning.
Cerium is now being used as a catalyst for purifying automobile exhaust, effectively preventing a large number of automobile exhaust from being released into the air. The United States accounts for a third of rare earth consumption in this application.
Cerium sulfide can replace lead, cadmium and other metals harmful to the environment and human beings to be used in pigments.
Cerium is used in a wide range of fields, including almost all rare earth applications. Such as polishing powder, thermoelectric material, cerium tungsten electrode, piezoelectric ceramics, gasoline catalyst, alloy steel, and Non-ferrous metal, etc.
Praseodymium is mainly used in glass, ceramics and magnetic materials.
It mixed with a ceramic glaze to make a colored glaze which has a pure, elegant color.
For making permanent magnets, using the cheap praseodymium-neodymium metal to replace the pure neodymium metal to make the permanent magnetic material, its anti-oxygen performance and mechanical performance are improved obviously, can be processed into various shapes of magnets. Widely used in all kinds of electronic devices and motors.
C. Used for catalytic cracking of petroleum, abrasive polishing, optical fiber applications and so on.
The largest user of the metal neodymium is the neodymium-iron-boron permanent magnet material. The appearance of nd-fe-b permanent magnet has injected new vitality and vigor into the field of rare earth high-tech. Neodymium is also used in Non-ferrous metal materials. The addition of 1.5 ~ 2.5% neodymium to magnesium or aluminum alloys can improve the high-temperature properties, gas tightness and corrosion resistance of the alloys, and is widely used as aerospace materials. In addition, neodymium also has great influence in medicine, glass, ceramics, rubber products.
Promethium is an artificial radioactive element from a nuclear reactor. the primary uses of promethium are (1) as a heat source. To provide auxiliary power for vacuum detection and satellites. (2) PM 147 emits low-energy radiation to make promethium batteries.
Samarium is the raw material for making samarium-cobalt permanent magnets. samarium-cobalt magnets are the first rare earth magnets to be used in the industry.
Europium oxide is mostly used in phosphors.
A. Its water-soluble paramagnetic complex can improve the human body’s magnetic resonance imaging signal in the medical field.
B. Its sulfur oxide can be used as the Matrix Grid of the Special Brightness Oscilloscope Tube and the x-ray screen.
C. Gadolinium in Gadolinium gallium Garnet is an ideal single substrate for bubble memory memory memory.
D. Without the limit of the Camot Cycle, can be used as a solid-state magnetic cooling medium.
E. Used as a chain reaction level inhibitor to control nuclear power plants to ensure the safety of nuclear reactions.
F. Used as an additive for Samarium cobalt magnets to ensure that the properties do not change with temperature. In addition, gadolinium oxide is used with Lanthanum to improve the thermal stability of the glass.
Terbium element is mainly used as an activator of green powder in fluorescent powder, magneto-optical storage material, magneto-optical glass, sonar, regulating mechanism of space telescope and aircraft wing regulator and so on applications.
Dysprosium plays an important role in many high-tech fields, such as additives for NdFeB permanent magnets, phosphor activators, necessary metal materials for Terfenol alloys, magneto-optical storage materials, neutron absorbers, etc.
Holmium is used as an additive in metal halide lamps, in yttrium iron or yttrium aluminum garnet, in Fiber-optic communication, and in medicine.
The optical properties of erbium are so outstanding that researchers have been paying much attention to it. ER3 + light emission at 1550nm is of special significance. The rapid development of Fiber-optic communication will open up new application fields for ER3 +.
Thulium can be used as a radiation source for portable medical X-ray machines, and can also be applied in clinical diagnosis and treatment of tumors, reducing the radiation and harm of X-ray to humans, which has important practical significance in medical applications.
Ytterbium-gadolinium gallium garnet embedded line waveguide laser has been successfully prepared by Japanese scholars, which is of great significance to the further development of laser technology. Ytterbium is also used as a phosphor activator, radio ceramic, computer memory element additive, glass fiber flux and optical glass additive.
Lutetium is mainly used for
A. Raw materials for bubble memory.
B. Making some special alloys;
C. Stable lutetium nuclide plays a catalytic role in petroleum cracking, alkylation, hydrogenation and polymerization.
D. Used as an addition to yttrium iron or yttrium aluminum garnet to improve some properties.
E. Used in energy cell technology and as an activator for phosphor.
F. It has been found that lutetium has potential applications in electrochromic display and low-dimensional molecular semiconductors.
Adding yttrium to the steel and non-ferrous alloys can improve the performance significantly. Yttrium-containing alloys with a high yttrium content of up to 90% can be used in aerospace and other applications requiring low density and high melting point. In addition, yttrium is also used as a high-temperature resistant coating material, a diluent for nuclear reactor fuel, an additive for permanent magnetic materials, and a getter in the electronics Industry.
In the electronics industry, scandium can be used as a semiconductor device, in the chemical industry, as an alcohol dehydrogenation and dehydrating agent, to produce ethylene and to produce chlorine from waste hydrochloric acid. In the glass industry, it is possible to make special glasses containing scandium. In the electric light source industry, Sodium lamp made of scandium and sodium has the advantages of high efficiency and positive color. In medicine, 46Sc is used to cure cancer.
Rare Earth metals have been widely used in electronics, petrochemical, metallurgy, machinery, energy, light industry, environmental protection, agriculture and other fields. Rare Earth can be used to produce fluorescent materials, rare earth hydride battery materials, electric light source materials, permanent magnetic materials, hydrogen storage materials, catalytic materials, precision ceramic materials, laser materials, Superconductor classification materials, magnetostrictive materials, magnetic refrigeration materials, magneto-optical storage materials, optical fiber materials, etc.