Ferrite Toroid Core: Nickel-Zinc Ferrite Fired at 1400 °C, Held at 930 °C (Snoek)

Ferrite is a ceramic magnet: iron oxide combined with other metal oxides, carrying magnetic flux while hardly conducting electricity. In his first ferrite patent (US 2,452,529, 1948) Snoek at Philips ground the oxides very fine and fired rings in oxygen. This nickel-zinc ferrite (20 : 30 : 50 mol %) is milled 30 hours, fired 1 hour at 1400 °C and held 16 hours at 930 °C; his core had an initial permeability of 560. Nickel oxide dust is a cancer hazard: respirator on. The picture: our diagram.