Permanent magnets include not only Neodymium magnets, but also Alnico and Samarium-Cobalt magnets. They differ not only in attracting power but also in the temperature at which they can operate without losing their magnetic properties.
Strongest Magnets - Neodymium Magnets
Neodymium magnets (Nd) are the strongest permanent magnets in the world. They are made from a magnetic material composed of a neodymium, iron, and boron alloy, forming the Nd2Fe14B structure. Neodymium magnets are considered part of the rare earth magnets family because their main component is a rare earth element, neodymium. Despite their name, rare earth elements are relatively abundant in the Earth's crust, although they are rarely found in concentrated form and are usually dispersed with other elements.
Samarium-Cobalt Magnets - Another Type of Rare Earth Magnets
Samarium-cobalt magnets (SmCo) were developed before neodymium magnets, and although they are not as strong as neodymium magnets, they have greater resistance to corrosion and can operate and maintain their performance at higher temperatures. To enhance the performance of neodymium and samarium-cobalt magnets, trace amounts of additional rare earth elements such as dysprosium (Dy) and praseodymium (Pr) are added.
Rare Earth Elements in the Periodic Table
The compound of neodymium, Nd2Fe14B, was first discovered in 1982 by General Motors and Sumitomo Special Metals. Since their initial introduction, stronger grades of neodymium magnets have become available in the market as production techniques have advanced. The strongest grade currently available is N55, although it is not yet widely used. More common grades are N42 and N52.
Electromagnets, which utilize electric currents to generate magnetic fields, can be much stronger than permanent magnets, but they require significant electric current to create a magnetic field.
Neodymium magnets are highly powerful due to their high resistance to demagnetization (coercivity) and high level of magnetic saturation, which allows them to generate large magnetic fields. The strength of a magnet is represented by its maximum energy product (BHmax), which is measured in Mega Gauss-Oersteds (MGOe). The maximum energy product is the product of remanence (Br) and coercivity (Hc) and represents the area under the curve of the second quadrant of the hysteresis loop.