Лако-красочные материалы — производство

Iron (Fe(III)), barium, and the dopants are precipitated as their hydroxides and react with an excess of sodium hydroxide solution (up to 6 mol l-1) 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 [5.27-5.31], the earliest report being from 1969 [5.32]. 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 [5.33-5.35].