Strontium-Calcium Ferrite Disc Magnet: Equal Strontium and Calcium, 1280 °C (Went, Philips 1956, Ex. 27)

A ferrite with half the strontium replaced by calcium: 0.3 mol strontium carbonate and 0.3 mol calcium carbonate to 3.1 mol iron oxide, milled 15 hours, pressed and passed through a 1280 °C furnace in 10 minutes. Went's rod held 1,645 gauss with a coercive force of 2,460 oersted. Source: J. J. Went, G. W. van Oosterhout and E. W. Gorter (Philips), US 2,762,777 (1956), Example 27. They sintered rods; discs and the magnetising are ours. Picture: ferrite magnets, Omegatron, Wikimedia Commons, CC BY-SA 3.0.