Cobalt oxide magnetic properties

Hydrothermal Method. Iron [Fe(III)], barium, and the dopants are precipitated as their hydroxides and reacted with an excess of sodium hydroxide solution (up to 6 mol/L) at 250-350 °C in an autoclave. This is generally followed by an annealing treatment at 750-800°C to obtain products with the desired magnetic properties. Many variations of the process have been described [5.36]-[5.40], the earliest report being from 1969 [5.41], In later processes, hydrothermal synthesis is followed by coating with cubic ferrites, a process resembling the cobalt modification of iron oxides (see Section 5.1.2). The object is to increase the saturation magnetization of the material [5.42]-[5.44],... 

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