Structure and magnetic properties of SmCoxTi0.4-1:7 ribbons

SmCoxTi0.4 (x = 6.6, 7.1, 7.6, 8.1) ribbons have been prepared by melt spinning at a wheel speed of 42 m/s, followed by annealing at 750 degrees C for 2 h. Both as-spun and as-annealed ribbons possess the disordered TbCu7-type (1: 7) phase even when the Sm/(Co, Ti) atomic ratio deviates from 1/7. The c/a ratio increases with increasing Co concentration x, but the unit cell volume decreases. The Curie temperatures show above 700 degrees C, increasing from 707 degrees C for x = 6.6 to 782 degrees C for x = 8.1. The saturation magnetizations increase almost linearly with increasing Co content. The observed magnetic hardening is believed to arise from the high magnetocrystalline anisotropy of the 1:7 phase and the fine nanograin structure. The intrinsic coercivity of 9797 Oe has been obtained in the melt-spun SmCo7.1Ti0.4 ribbons. (C) 2007 Elsevier B.V. All rights reserved.