Preparation of barium ferrite films with high Fe/Ba ratio by sol–gel method

Hexagonal BaFe12O19 ferrite (BaM) thin films were prepared on Si (100) substrate successfully by sol–gel technology and post annealing. The results showed the BaM phase can be formed and crystallized into c-axis textured grains even when the Fe/Ba ratio of the precursor varied from 6.5 to 9.5. However, the behavior of the saturation magnetization (M s) and intrinsic coercivity (H c) depended strongly on the Fe/Ba ratio and annealing temperature (T a) varied from 700 to 900 °C. The M s and H c values deceased with an increase of Fe/Ba ratio, for instance, were about 290 emu/cm3 and 4,200 Oe for the Fe/Ba = 6.5 film but only 116 emu/cm3 and 2,300 Oe for the Fe/Ba = 9.5 film. The M s and H c values of the Fe/Ba ratio = 6.5 film increased monotonously with increasing T a, were about 120 emu/cm3 and 2,500 Oe at T a = 800 °C, and reached to 345 emu/cm3 and 4,600 Oe at T a = 950 °C.