Patent ID: RE40348

Claim:
A thin arc segment magnet having a thickness of 1-4 mm and made of a an R- T - B - based, rare earth sintered magnet having a main component composition comprising 28-33 weight % of R and 0.8-1.5 weight % of B, the balance being substantially Fe T , wherein R is at least one rare earth element including Y, and T is Fe or Fe and Co, said arc segment magnet having an oxygen content of 0.3 weight % or less , a carbon content of 0 . 10 weight % or less and a nitrogen content of 0 . 15 weight % or less based on the total weight of the magnet, a density of 7.56 g/cm 3 or more, a coercivity iHc of 1.1 MA/m (14 kOe) or more at room temperature, and an orientation Br/4πI max of 96% or more in an anisotropy-providing direction at room temperature , Br being a residual magnetic flux density, and 4 πI max being a maximum value of 4 πI in a curve of 4 πI - H curve, wherein 4 πI is the intensity of magnetization, and H is the intensity of a magnetic field .