Magnetic hysteresis of mechanically alloyed Sm–Co nanocrystalline powders

Authors

J. Zhou, University of Nebraska - Lincoln
Ralph Skomski, University of Nebraska-LincolnFollow
David J. Sellmyer, University of Nebraska-LincolnFollow

Document Type

Article

Date of this Version

May 2003

Comments

Published by American Institute of Physics. J. Applied Physics 93, 6495-6497 (2003). ©2003 American Institute of Physics. Permission to use. http://jap.aip.org/jap/.

Abstract

Mechanically alloyed Sm–Co powders and Sm₁₂ (Co,Cu,Ti) ₈₈ powders are investigated. X-ray diffraction patterns show that after annealing, structures of 2:7, 1:5, and 1:7 phases form. A room-temperature coercivity of 41 kOe was obtained in Sm₂Co₇ powders. Magnetic hysteresis was investigated by the method of δ m curves. Positive value δ m curves were obtained in Sm₂Co₇ and SmCo₅, while negative values were found in SmCo_7.3 and SmCo₈ indicating different magnetization reversal mechanisms. Nanocrystalline powders of Sm₁₂ (Co,Cu,Ti) ₈₈ with a mixture of 1:5 and 2:17 phases form after long-time heat treatment. The intrinsic coercivity of the powders increases with an increasing amount of Cu. Short annealing time produces 1:7 phase with higher crystalline anisotropy, which results in larger coercivity.