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Rare earth elements used in magnets

Rare earth elements used in magnets

Issue Time:2018-10-17

Rare earth is the abbreviation of a group of metals, including 17 elements in the periodic table of chemical elements, such as lanthanum, cerium, and praseodymium. It has been widely used in many fields such as electronics, petrochemicals, metallurgy and so on.

The following is a list of the uses of neodymium praseodymium (PrNd), samarium cobalt (SmCo) and dysprosium (Dy).

1. Pr

About 160 years ago, the Swedish Mossander discovered a new element from lanthanum, but it is not a single element. Mossander discovered that the nature of this element is very similar to lanthanum, so he named it "PrNd". "Pr" means "twin" in Greek. About 40 years later, the Austrian Welsbach successfully separated two elements from the "Pr-neodymium", one named "neodymium" and the other named "praseodymium". And the praseodymium element found can be used in glass, ceramics, and magnetic materials.


(1) Praseodymium is widely used in architectural ceramics and daily-use ceramics. It is mixed with ceramic glaze to make colored glaze, or it can be used as underglaze pigment alone. which made pure light-yellow pigment.


(2) Used to make permanent magnets. Using cheap praseodymium metal instead of pure neodymium metal to make permanent magnet materials, its oxygen resistance and mechanical properties are obviously improved, and it can be processed into magnets of various shapes. It is widely used in various electronic devices and motors.


(3) Used in petroleum catalytic cracking. The petroleum cracking catalyst is prepared by adding praseodymium and neodymium enrichment to Y-type zeolite molecular sieve, which can improve the activity, selectivity, and stability of the catalyst. China began to use it in industrial in the 1970s, and its consumption continued to increase.


(4) Pr can also be used for abrasive polishing. In addition, the use of praseodymium in the field of optical fiber is becoming more and more extensive.

2. Nd

With the birth of praseodymium, neodymium also emerged. The advent of neodymium has activated the rare earth field, played an important role in the rare earth field, and controlled the rare earth market.


With its unique position in the rare earth field, neodymium has become a hot spot in the market for many years. The most use of neodymium is in NdFeB permanent magnet.


The advent of NdFeB magnets has injected new vitality into the rare earth high-tech field. NdFeB magnets have high magnetic energy product and are called the "king of permanent magnets". They are widely used in electronics, machinery, and other industries with their excellent performance. Neodymium is also used in non-ferrous metal materials. Adding 1.5 to 2.5% neodymium to magnesium or aluminum alloy can improve the high temperature performance, air tightness and corrosion resistance of the alloy, so it’s also widely used as aerospace materials. In addition, neodymium-doped yttrium aluminum garnet produces short-wave laser beams, which are widely used in the industry for welding and cutting thin materials with a thickness of less than 10mm. In medical treatment, neodymium-doped yttrium aluminum garnet lasers are used instead of scalpels to remove surgical or disinfect wounds. Neodymium is also used for the coloring of glass and ceramic materials and additives for rubber products.

3. Sm

In 1879, Bois Baudler discovered a new rare earth element in the "praseodymium neodymium" obtained from the niobium and yttrium ore, and named it samarium after the name of this ore.


Samarium is light yellow and is the raw material for samarium-cobalt (SmCo) permanent magnets. SmCo magnets are the first rare-earth magnets to be industrially used. There are two types of such permanent magnets: SmCo5 series and Sm2Co17 series. The SmCo5 series were invented in the early 1970s, and the Sm2Co17 series were invented in the later period of 1970s. Now the mainly demand is the latter one. The purity of samarium oxide used in SmCo magnets does not need to be too high. Considering the cost, about 95% purity of products are mainly used. In addition, samarium oxide is also used in ceramic capacitors and catalysts. In addition, samarium also has nuclear properties and can be used as a structural material for atomic energy reactors, shielding materials and control materials, so that the huge energy generated by nuclear fission can be used safely.

4. Dy

In 1886, the Frenchman Bois Boudre successfully separated holmium into two elements, one is still called holmium, and the other is named dysprosium based on the meaning of "hard to get" from holmium. Dysprosium currently plays an increasingly important role in many high-tech fields.


The main uses of Dysprosium are:


(1) Used as an additive for NdFeB permanent magnets. Adding about 2% to 3% of dysprosium to this magnet can increase its coercivity. In the past, the demand for dysprosium was not much, As the demand for magnets increases, it becomes a necessary additional element, and the ore grade must be around 95% to 99.9%. The demand of Dy is also increasing rapidly.


(2) Dysprosium is used as a phosphor activator. Trivalent dysprosium is a promising single-luminescence center three-primary-color luminescent material active ion, which is mainly composed of two emission bands, one is yellow light emission, the other is blue light Emitting, dysprosium-doped luminescent materials can be used as three primary color phosphors.


(3) Dysprosium is a necessary raw material for the large magnetostrictive alloy terbium and dysprosium (Terfenol) alloy, which can realize the precise activities of some mechanical movements.


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


(5) For the preparation of dysprosium lamps, the working substance used in dysprosium lamps is dysprosium iodide. This kind of lamp has the advantages of large brightness, good color, high color temperature, small volume, stable arc, etc., and has been used in movies and printing Wait for the lighting source.


(6) Due to the large cross-sectional area of neutron capture, dysprosium is used in the atomic energy industry to measure neutron energy spectrum or as a neutron absorber.


(7) Dy3Al5O12 can also be used as a magnetic working material for magnetic refrigeration. With the development of science and technology, the application fields of Dysprosium will continue to expand and extend.