Development of Magnet

The development of magnets has a long history,
Natural magnets were discovered 5000 years ago (Fe304)

　　2300 years ago, the Chinese people ground natural magnets into spoon shapes and placed them on a smooth plane. Under the action of geomagnetism, the spoon handle guide was called "Sinan", which was the first guide instrument in the world.

　　1000 years ago, Chinese people used magnets and iron needles to make the world's earliest compass.

　　Around 1100, China linked the magnet needle and the azimuth disk into a whole, becoming a magnet-type pointing instrument for navigation.

　　1405-1432 Zheng He started the great pioneering work of navigation in human history with the South-pointing instrument.

　　1488-1521 Columbus, Gamma, Magellan made a world-famous nautical discovery with a guide from China.

　　1600 Englishman, William. Gibb published a monograph on magnetism, "Magnet", which repeated and developed previous knowledge and experiments on magnetism.

　　The 1785 French physicist C. Coulomb established the "Coulomb's law" which describes the force between the charge and the magnetic pole ".

　　1820 Danish physicist H.C. Oerst discovered that current-induced magnetism.

　　1831 British physicist M. Faraday discovered the phenomenon of electromagnetic induction.

　　1873 British physicist J.C. Maxwell completed the unified electromagnetic theory in his monograph "on electricity and magnetism.

　　1898-1899 French physicist P. Curie discovered that ferromagnetic substances become paramagnetic at a specific temperature (Curie temperature).

　　1905 French physicist P.I. Lang Zhiwan explained the variation of paramagnetism with temperature based on the theory of statistical mechanics.

　　1907 French physicist P.E. Wais proposed molecular field theory, which extended Lang Zhiwan's theory.

　　1921 Austrian physicist W. Pauli proposed Bohr magneton as the basic unit of atomic magnetic moment. American physicist A. Compton proposed that electrons also have a magnetic moment corresponding to spin.

　　1928 British physicist P.A.M. Dirac used relativistic quantum mechanics to perfectly explain the intrinsic spin and magnetic moment of electrons. Together with the German physicist W. Heisenberg, he proved the existence of the exchange force of the origin of static electricity, which laid the foundation of modern magnetism.

　　1936 Soviet physicist Lang Dao completed the masterpiece "Theoretical Physics Tutorial", which contains a comprehensive and wonderful discussion of modern electromagnetism and ferromagnetism.

　　From 1936 to 1948, French physicist L. Nail proposed the concept and theory of antiferromagnetism and ferrimagnetism, and deepened the understanding of material magnetism in the following years of research.

　　1967 Austrian physicist K.J. Snat discovered rare earth magnets (SmCo5) with unprecedented high magnetic energy product under the guidance of quantum magnetism, thus opening a new chapter in the development of permanent magnet materials.

　　In 1967, Strnat of Dayton University in the United States, developed into a samarium cobalt magnet, marking the arrival of the era of rare earth magnets.

　　1974 the second generation of rare earth permanent magnet-Sm2Co17 came out.

　　The third generation of rare earth permanent magnet-Nd2Fe14B came out in 1982. Neodymium magnet was invented in 1982 by Sagawa Shinto of Sumitomo Special Metals Company. According to its chemical formula, it is mainly composed of chemical elements such as neodymium, iron and boron. It can produce various shapes: such as disc magnet, ring magnet, rectangular magnet, arc magnet and other shapes of magnet, which are widely used in motors, instruments and meters, and automobile industry, petrochemical industry and magnetic health care products.

　　1990 atom gap magnet-Sm-Fe-N came out.

　　1991 German physicist E.F. Kneeler proposed the theoretical basis of the exchange interaction of two-phase composite magnets and pointed out the development of nanocrystalline magnets.

Source: magnet manufacturers Youlian Magnetic Industrywww.youliancy.com