Influence of Ba content on grain size and dynamics of crystallization in barium ferrite thin films

The effects of Ba content on the dynamics of the crystallization process, which ultimately determines the grain size, were studied in barium ferrite thin films. Rapid thermal annealing was used to crystallize the amorphous as-deposited barium ferrite films. The annealing time and temperature dependent crystalline volumes were determined from the magnetization of the films, and were analyzed by means of the Johnson-Mehl-Avrami relation. Microstructural studies showed that the films with higher Ba content had higher nucleation rates and lower growth rates; consequently, they had finer grain size and smaller grain aspect ratio. Magnetic measurements showed that the higher Ba content films also had higher coercivities and smaller magnetic switching volumes. (C) 1997 American Institute of Physics.