Sumitomo Metal Mining Company, Ltd.

Tatsuo Nate

Koichi Oka

Toshio Morimoto

Takehiko Sato

Takehiko Satoh

An alloy target for making a magneto-optical recording medium by sputtering comprises an alloy containing 10 to 50 atom % of at least one rare earth element selected from among Sm, Nd, Gd, Tb, Dy, Ho, Tm and Er, with a balance consisting substantially of at least one transition metal selected from among Co, Fe and Ni. The alloy has a mixed structure composed of at least one phase of an intermetallic compound formed by the rare earth element and the transition metal and a phase of the rare earth element along.

Alloy target for manufacturing a magneto-optical recording medium

Magnetic powder of the samarium/praseodymium/cobalt type and of the samarium/praseodymium/neodymium/cobalt type having specific compositions is substantially composed of (1-5) single phase, has improved residual magnetic flux density and a high maximum energy product, and is hence suitable for resin magnets. In addition, production cost is lower compared with conventional rare-earth metal/cobalt type magnet powder because part of samarium metal has been replaced by praseodymium and neodymium which are more abundant and less expensive materials.

Rare-earth element/cobalt type magnet powder for resin magnets

A rare earth-element/cobalt type magnetic powder which possesses outstanding magnetic properties and which is useful for making a resin magnet is produced by a method which comprises thermally reducing a mixture consisting of oxide of samarium, oxide of praseodymium, optionally oxide of neodymium, and cobalt powder, thereby causing diffusion of consequently produced samarium, praseodymium, and/or neodymium in the cobalt powder, subjecting the resultant reaction product to a heat-treatment involving standing at 600.degree. to 900.degree. C. for 30 minutes to 5 hours and subsequent quenching from this temperature at a rate of not less than 10.degree. C./minute, adding the product of the heat-treatment to water, thereby converting the product into a slurry, treating the slurry with water and an aqueous acid solution, and comminuting the resulting powder into particles of an average diameter of 3 to 10 .mu.m thereby obtaining a magnetic powder having a composition represented by Sm.sub.1-x Pr.sub.x Co.sub.z or Sm.sub.1-x Pr.sub.x-y Nd.sub.y Co.sub.z (wherein x, y, and z satisfy the relations 0.05.ltoreq.x.ltoreq.0.40, 0.01.ltoreq.y.ltoreq.0.39, 0.01.ltoreq.x-y.ltoreq.0.39 and 4.7.ltoreq.z.ltoreq.5.3).

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Ichikawa, Japan

Tatsuo Nate