Barium-Calcium Ferrite Disc Magnet: 5 % Calcium, Sintered at 1330 °C (Went, Philips 1956, Ex. 18)

A ceramic magnet with a twentieth of the barium replaced by calcium: 0.095 mol barium carbonate, 0.005 mol calcium carbonate and 0.6 mol iron oxide. It is milled, fired in air, milled again, pressed and passed through a 1330 °C furnace in 10 minutes. The X-ray picture showed only the magnetoplumbite phase. Went's rod held 1,680 gauss with a coercive force of 1,110 oersted. Source: J. J. Went, G. W. van Oosterhout and E. W. Gorter (Philips), US 2,762,777 (1956), Example 18. They sintered rods; discs and the magnetising are ours. Picture: ferrite magnets, Omegatron, Wikimedia Commons, CC BY-SA 3.0.