Strontium Ferrite Disc Magnet: Presintered, 4 Minutes at 1150 °C (Went, Philips 1956, Ex. 25)

A strontium ferrite with more strontium: 0.4 mol strontium carbonate to 0.8 mol iron oxide, milled, presintered at 1000 °C, milled again, pressed and passed through a 1150 °C furnace in 4 minutes. Went's rod held 1,200 gauss with a coercive force of 3,710 oersted. Source: J. J. Went, G. W. van Oosterhout and E. W. Gorter (Philips), US 2,762,777 (1956), Example 25. They sintered rods; discs and the magnetising are ours. Picture: ferrite magnets, Omegatron, Wikimedia Commons, CC BY-SA 3.0.