As a kind of rare-earth permanent magnet--Samarium Cobalt(the following called SmCo-magnet) is widely used second generation rare-earth magnetic material. SmCo magnet is made from cobalt and samarium and other rare-earth elements, is a high performance permanent magnet, it exhibits high magnetic performance characteristics in energy and coercive force. There are two compositions of magnets in this family: Sm1Co5 and Sm2Co17. The highest commercially available energy products of Sm2Co 17 are in the 30MGOe range. The 2:17(most popular) offers a better performance & lower temperature coefficient, however it is slightly more expensive and require very high magnetic field to magnetise it.
SmCo-magnet has higher maximum working temperatures than neodymium, although its maximum strengh is less. Its biggest advantage is its high working temperature up to 300 degree centigrade. In the meantime, its higher corrosion and oxidation resistance are also crucial. So SmCo magnets usually need not be plated with other metal. The cost of SmCo material is the most expensive, so SmCo-magnet is recommended only when its performance is a high temperature environment concerned.