SOFT-MAGNETIC PROPERTIES OF FINE CRYSTALLINE FE-BN AND FE-BN-O FILMS

Fe-BN and Fe-BN-O films were prepared by co-sputtering of Fe and boron nitride (BN) targets in an Ar atmosphere and an Ar-O2 atmosphere respectively. In the as-deposited amorphous state, their electrical resisitivity rho increases with increasing O2 flow ratio in the sputtering gases. Fe-BN films have a positive large saturation magnetostriction lambda(s) as ordinary Fe-based amorphous alloys do, but the addition of oxygen decreases lambda(s). These films are crystallized into the b.c.c. Fe phase by annealing. The crystallized Fe-BN-O films exhibit good soft magnetic properties with high rho and low lambda(s) (H almost-equal-to 0.1 Oe; mu almost-equal-to 1500; rho almost-equal-to 1500 muOMEGA cm; lambda(s) almost-equal-to + 5 x 10(-6). These soft magnetic properties and lower magnetostriction are attributed to fine b.c.c. Fe grains surrounded by ceramic-like boundaries.