MAGNETIC AND STRUCTURAL-PROPERTIES OF BA-FERRITE FILMS PREPARED BY SOL-GEL PROCESSING

The magnetic properties and microstructure of barium ferrite films (Ba Fe12O19) coated by a sol-gel technique involving a spin coating of met al-organic compounds are investigated. The in-plane magnetic propertie s and the grain size are controlled by a Fe/Ba atomic ratio in the coa ting solution and annealing conditions. The in-plane coercivity increa ses as the decrease of the Fe/Ba ratio and the increase of the anneali ng temperature. Maximum value of 4-6 kOe is obtained at the Fe/Ba rati o of 2-8 with the annealing at 900 degrees C for 10 min. At these prep aration conditions, the c axis of the hexagonal barium ferrite is slig htly oriented parallel to the film plane. The grain size decreases as the decrease of the Fe/Ba ratio. The films with the Fe/Ba ratio of 4-6 show a grain size of almost one-tenth of that of the sputtered-films without additives such as Cr2O3 or CoTi. The smaller grain size of the sol-gel-coated films is probably due to the high nucleation density a t the annealing process. (C) 1996 American Institute of Physics.