Magnetic Ceramics: VII, Effect of Iron Oxide Particle Size on Nickel Ferrite Formation

Five iron oxides of increasing particle‐size distribution, mixed with nickel oxide of a constant‐size range, were heated at various temperatures and time intervals. The extent of nickel ferrite formation, as influenced by particle‐size distribution of the iron oxide constituent, was measured with a compensating‐coil magnetometer. Using the Jander relation for this type of reaction, activation energies ranging from 54 to 70 kcal. were computed for increasing particle size. These results are examined and compared with current procedures for the production of ferrite powders.