Oriented Strontium Ferrite Disc Magnet: Agate-Milled, 10,000 Oersted Field (Gorter, Philips 1956, Ex. 8)

A strontium ferrite magnet oriented in a magnetic field: strontium carbonate and iron oxide milled, pre-fired 2 hours at 1000 °C, ground fine in an agate mill, then oriented, heated and sintered as in Example 4. In the principal direction it held 2,640 gauss with a coercive force of 2,825 oersted and a (BH)max of 1.63 × 10⁶. Source: E. W. Gorter, G. W. Rathenau and A. L. Stuyts (Philips), US 2,762,778 (1956), Example 8. They made blocks; disc size is ours. Picture: ferrite magnets, Omegatron, Wikimedia Commons, CC BY-SA 3.0.