A new permanent magnet of high coercive force and maximum energy product has been prepared and named BISMANOL. It has been previously shown by numerous investigators that if the particle size of a ferromagnetic material is so reduced that each particle represents a single magnetic domain, the three chief factors determining the coercive force are: n1) magnetic crystal anisotropy, n2) particle shape anisotropy, nand 3) internal strain anisotropy. Accordingly, compacts have been prepared of the finely pulverized intermetallic compound manganese Msmuthide exhibiting permanent magnet characteristics. The compound HnBi was chosen because it has the highest recorded magnetic crystal anisotropy constant. Some of these pressed magnets showed a maximum energy, product (BH)max as high as 2.9 x 106 gauss-oersteds, a coercive force (Hc) of 3100 oersteds and a residual flux density(Br) of 3400 gauss. Of known permanent magnetic materials, only the high cobalt alloys and the platinum-iron alloy exceed £his new material in maximum energy product. No known magnetic material exceeds this new magnet in coercive force. This preliminary work shows that aside from its possibilities as a substitute for magnets requiring cobalt, this new magnet material has a value which exceeds present materials for special applications where a high coercive force is desirable, as, for example, where one cannot use a magnet that is long compared to the air gap required. There is also theoretical possibility of further improvement in maximum energy product. No technical evaluation of the material with respect to temperature, stability, aging, shock, etc., is available at present.
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