Barium-Calcium Ferrite Disc Magnet: 20 % Calcium, 5 Minutes at 1290 °C (Went, Philips 1956, Ex. 20)

A ceramic magnet with a fifth of the barium replaced by calcium: 0.08 mol barium carbonate, 0.02 mol calcium carbonate and 0.6 mol iron oxide, made as in Example 18 but sintered at 1290 °C for only 5 minutes. Went's rod held 1,615 gauss with a coercive force of 1,550 oersted. Source: J. J. Went, G. W. van Oosterhout and E. W. Gorter (Philips), US 2,762,777 (1956), Example 20. They sintered rods; discs and the magnetising are ours. Picture: ferrite magnets, Omegatron, Wikimedia Commons, CC BY-SA 3.0.