What is heavy rare earth?

- Nov 01, 2017 -

Heavy rare earth Overview:

According to the physical and chemical properties of rare earth elements and geochemical properties of certain differences and separation process requirements, scholars tend to rare earth elements are divided into light, heavy two groups or light, medium and heavy three groups. The two groups of ginseng as the boundary, gadolinium before the lanthanum, dysprosium, cerium, praseodymium, neodymium, samarium, europium 7 elements for the light rare earth elements, also known as cerium rare earth elements; gadolinium and gadolinium after terbium, Dysprosium, holmium, erbium, thulium, ytterbium, lutetium and yttrium and other nine elements called heavy rare earth elements, also known as yttrium group rare earth elements. Although the atomic weight of yttrium is only 89, its chemical properties are closer to heavy rare earth elements due to its ionic radius in the ionic radius of other heavy rare earth elements. In nature and other heavy rare earth elements symbiotic. It is classified as heavy rare earth group. There are no rules for the classification of rare earths in three groups, such as lanthanum, cerium, praseodymium, neodymium, samarium, and the micro-soluble terbium group, that is, Rare earth group, including europium, gadolinium, terbium, dysprosium; more soluble yttrium group that is heavy rare earth group, including yttrium, holmium, erbium, thulium, ytterbium, lutetium. However, the difference in solubility between adjacent elements between groups is very small, and this method is not net. (20) ethylhexyl (phosphoric acid), i.e., P204, can be grouped between neodymium and samarium and then grouped between gadolinium and terbium. Here, lanthanum, cerium, praseodymium, neodymium called light rare earth, samarium, europium, gadolinium called rare earth, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutium plus yttrium called heavy rare earth.

Heavy rare earth elements:



(D), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Tb), tantalum (Tb), ytterbium Lu), yttrium (Y) is called heavy rare earth element, also known as yttrium group (yttriumgroup).

The content of rare earth in the crust is not scarce, the clinker value of this group of elements is 0.0236%, the cerium group element is 0.01592%, the yttrium group element is 0.0077%; the common element copper (0.01%), zinc (0.005% Tin (0.004%), lead (0.0016%), nickel (0.008%), cobalt (0.003%) and so on.

Gadolinium (Gd):

1, its water-soluble paramagnetic complex can improve the human body's nuclear magnetic resonance (NMR) imaging signal.

2, the sulfur oxide can be used as a special brightness of the oscilloscope and x-ray phosphor screen grid grid.

3, gadolinium in gadolinium gallium garnet for the bubble memory is the ideal single substrate.

4, in the absence of Camot cycle restrictions, can be used as solid-state magnetic refrigerant.

5, for the control of nuclear power plant chain reaction level of inhibitors to ensure the safety of nuclear reactions.

6, used as samarium cobalt magnets additives to ensure that performance does not vary with the degree. In addition, gadolinium oxide used together with lanthanum, contribute to changes in the vitrification area and improve the thermal stability of the glass. Gadolinium oxide can also be used to make capacitors, x-ray sensitizers. In the world is currently working to develop gadolinium and its alloys in the application of magnetic refrigeration, has made a breakthrough, the use of superconducting magnets, metal gadolinium or its alloys for the cooling medium of the magnetic refrigerator has come out.

Terbium (Tb):

1, phosphor for the three primary colors of phosphor powder in the green powder activator, such as terbium activated phosphate matrix, terbium activated silicate matrix, terbium activated cerium magnesium aluminate matrix, in the excited state are issued Green light.

2, magneto-optical storage materials, in recent years, terbium-based magneto-optical materials have reached the scale of mass production, with Tb-Fe amorphous film developed magneto-optical discs for computer storage components, storage capacity increased by 10 to 15 times.

3, magneto-optic glass, terbium-containing Faraday-rotating glass is a key material for the manufacture of rotators, isolators and circulators widely used in laser technology. Especially terbium dysprosium magnetostrictive alloy (TerFenol) development, but also opened up a new use of terbium, Terfenol placed in a magnetic field, the size of the change than the general changes in the magnetic material such a change can make some Precision mechanical movement can be achieved. Terbium Dysprosium Iron is mainly used for sonar, and has been widely used in a variety of fields, from fuel injection systems, liquid valve control, micro-positioning to mechanical actuators, mechanisms and aircraft space telescopes for regulating wing finder and other fields.

Dysprosium (Dy):

1, as NdFeB permanent magnet additives used in this magnet to add about 2 to 3% of dysprosium, can increase its coercivity, dysprosium in the past the demand is not large, but with the demand for NdFeB magnets Of the increase, it becomes necessary to add elements, grade must be 95 ~ 99.9%, demand is also increasing rapidly.

2, dysprosium as a phosphor activator, trivalent dysprosium is a promising single-light center three primary luminescent material of the activation of ions, it is mainly composed of two emission bands, one for the yellow light, the other for the blue light , Doped dysprosium luminescent material can be used as a three-color phosphor.

3, dysprosium is the preparation of large magnetostrictive alloy terbium dysprosium (Terfenol) alloy of the necessary metal raw materials, can make some mechanical movement of precision activities can be achieved.

4, dysprosium metal can be used as a magneto-optical storage material, with a high recording speed and reading sensitivity.

5, for the preparation of dysprosium lamp, dysprosium lamp used in the working material is dysprosium iodide, this lamp has a large brightness, good color, high color, small size, arc stability, etc., has been used for film, printing, etc. Lighting source.

6, because dysprosium element has a neutron capture cross-sectional area of the characteristics of the atomic energy industry used to determine the neutron spectrum or neutron absorber.

7, Dy3Al5O12 can also be used as magnetic work with magnetic properties. With the development of science and technology, dysprosium application areas will continue to expand and extend.

Holmium (Ho):

1, used as a metal halide lamp additive, metal halogen lamp is a gas discharge lamp, it is developed on the basis of high pressure mercury lamp, which is characterized in the bulb filled with a variety of rare earth halide. At present, the main use of rare earth iodide, in the gas discharge issued a different line of light color. Holmium lamp used in the working material is holmium iodide, in the arc area can get a higher metal atomic concentration, thus greatly improving the radiation efficiency.

2, holmium can be used as yttrium iron or yttrium aluminum garnet additives.

3, holmium - doped yttrium aluminum garnet (Ho: YAG) can emit 2μm laser, human tissue on 2μm laser absorption rate is high, almost three times higher than Hd: YAG order of magnitude. Therefore, Ho: YAG laser for medical surgery, not only can improve the efficiency and accuracy of surgery, but also to reduce the thermal damage to a smaller area. Hollow crystals produce free beams that eliminate fat and do not produce excessive heat, thereby reducing the thermal damage to healthy tissue. It is reported that holmium laser treatment of glaucoma in the United States can reduce the pain of patients with surgery. China's 2μm laser crystal level has reached the international level, should vigorously develop and produce this laser crystal.

4, in the magnetostrictive alloy Terfenol-D, you can also add a small amount of holmium, thereby reducing the saturation magnetization of the alloy required field.

5, in addition to the use of holmium-doped fiber can be made fiber lasers, fiber amplifiers, fiber optic sensors, etc. Optical communication devices in today's fiber-optic communications will play a more important role.

Erbium (Er):

1, Er3 + at 1550nm has a special significance, because the wavelength is located in the optical fiber communication optical fiber minimum loss, erbium ion (Er3 +) by the wavelength of 980nm, 1480nm light excitation, from ground state 4I15 / 2 transition to high energy When the Er3 + in the high energy state jumps back to the ground state, the 1550nm wavelength is emitted. The quartz fiber can transmit light of different wavelengths, but the different light and light decay rates are different. The light in the 1550nm band is in the quartz The lowest decay rate (0.15 dB / km) is transmitted in the fiber, almost the lower limit attenuation rate. Therefore, the optical fiber communication at 1550nm for the signal light, the light loss is minimal. In this way, if the appropriate concentration of erbium into the appropriate matrix, according to the laser principle, the amplifier can compensate for the loss of communication systems, so need to amplify the wavelength of 1550nm optical signal in the telecommunications network, erbium-doped fiber amplifier is no Smaller optical devices, currently erbium-doped silica fiber amplifiers have been commercialized. It is reported that in order to avoid useless absorption, the amount of erbium doped in the fiber is tens to hundreds of ppm. The rapid development of optical fiber communication will open up new areas of erbium application.

2, the other erbium-doped laser crystal and its output of 1730nm laser and 1550nm laser on the human eye safety, atmospheric transmission performance is better, the battlefield smoke penetration ability, confidentiality is good, easy to be detected by the enemy, The target of a larger contrast, has been made with the military on the human eye safe portable laser range finder.

3, Er3 + added to the glass can be made of rare earth glass laser material, is the output pulse energy, the highest output power of solid laser materials.

4, Er3 + can also be done on the conversion of rare earth laser materials activated ions.

5, the other erbium can also be applied to glass glasses, crystal glass decolorization and coloring.

Thulium (Tm):

1, thulium for medical light X-ray machine source, thulium in the nuclear reactor after irradiation to produce an X-ray isotope can be used to manufacture portable blood irradiator, this radiometer can make thulium -169 by The role of high neutron beam into thulium -170, radiating X-ray irradiation of blood and white blood cells decreased, and it is these leukocytes caused by transplant rejection, so as to reduce the early rejection of the device.

2, thulium element can also be used in clinical diagnosis and treatment of cancer, because it has a high affinity for tumor tissue, heavy rare earth rare earth affinity than light, especially in the largest affinity of thulium elements.

3, thulium in the X-ray screen with a fluorescent agent Activator LaOBr: Br (blue), to enhance the optical sensitivity, thereby reducing the X-ray exposure to human exposure and damage with the previous tungstate Which can reduce the X-ray dose by 50%, which has important practical significance in medical applications.

4, thulium can also be in the new lighting source metal halogen lamp to do additives.

5, Tm3 + added to the glass can be made of rare earth glass laser material, which is the largest output pulse, the highest output power of solid laser materials. Tm3 + can also be used to convert the activated material of the rare earth on the laser material.

Yb (Yb):

1, for the thermal shielding coating material. Ytterbium can significantly improve the corrosion resistance of the electrodeposited zinc layer, and the ytterbium-containing coating is smaller than the ytterbium-free coating and is uniform and compact.

2, for magnetostrictive materials. This material has a magnetostrictive property that is expanding in the magnetic field. The alloy is mainly composed of ytterbium / ferrite alloy and dysprosium / ferrite alloy, and add a certain proportion of manganese, in order to produce giant magnetostrictive properties.

3, for the determination of the pressure of ytterbium components, experiments show that ytterbium components in the calibration of the pressure range of high sensitivity, while ytterbium in the application of pressure measurement has opened up a new way.

4, the teeth of the hollow resin-based filler to replace the general use of amalgam in the past. 5, Japanese scholars successfully completed the ytterbium-doped gadolinium gallium garnet embedded line waveguide laser preparation work, the completion of this work on the further development of laser technology is very meaningful. In addition, ytterbium is also used for phosphor activators, radio ceramics, electronic computer memory elements (bubble) additives, and glass fiber fluxes and optical glass additives.

Lutetium (Lu):

1, the manufacture of some special alloys. For example, lutetium aluminum alloy can be used for neutron activation analysis.

2, stable lutetium nuclides in the oil cracking, alkylation, hydrogenation and polymerization in the catalytic role.

3, yttrium iron or yttrium aluminum garnet add elements to improve certain properties.

4, the raw material of the bubble storage.

5, a composite functional crystal doped with lutetium borate tetraphenyl borate neodymium, belonging to the salt solution cooling growth of the technical field, experiments show that lutetium doped NYAB crystal in the optical uniformity and laser performance are better than NYAB crystal.

6, the relevant departments of foreign research found that lutetium in electrochromic display and low-dimensional molecular semiconductors in the potential use. In addition, lutetium is also used for energy battery technology and phosphor activator.

Yttrium (Y):

1, iron and steel and nonferrous alloy additives. FeCr alloy usually contains 0.5-4% yttrium, yttrium can enhance the oxidation resistance and ductility of these stainless steel; MB26 alloy with the appropriate amount of yttrium-doped mixed rare earth, the alloy's comprehensive performance has been significantly improved, can replace part of the strong aluminum Alloy is used in the mechanical force of the aircraft; adding a small amount of yttrium-containing rare earth in Al-Zr alloy can improve the conductivity of the alloy; the alloy has been used for most domestic wire factory; adding yttrium in the copper alloy, improving the conductivity And mechanical strength.

2, containing yttrium 6% and aluminum 2% silicon nitride ceramic material, can be used to develop engine parts.

3, with a power of 400 watts of neodymium yttrium aluminum garnet laser beam to large components for drilling, cutting and welding and other mechanical processing.

4, Y-Al garnet single-chip composed of electron microscopy phosphor screen, high brightness, low absorption of scattered light, high resistance and resistance to mechanical wear performance.

5, containing yttrium up to 90% of the high yttrium structure alloy, can be used in aviation and other requirements of low density and high melting point of the occasion.

6, the current much attention to the yttrium SrZrO3 high proton conductive material, the fuel cell, electrolytic cell and the need for high hydrogen solubility of gas sensor production is of great significance. In addition, yttrium is also used for high spray coating materials, atomic reactor reactor fuel diluent, permanent magnet material additives and the electronics industry as a getter.

Information, biology, new materials, new energy, space and the ocean by contemporary scientists pushed to six new science and technology group, people pay attention to rare earth, research rare earth, the development of rare earth, is rare earth elements in the six science and technology group has its The ability to display their talents. However, rare earth elements, after all, is still a group of people not yet fully aware of the elements, which requires great efforts to study and understand them, so as to hold them, so that they have a greater contribution to mankind, rare earth elements will be high The development of science and technology in the full vitality.

Article from NdFeB Industry Network

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