Magnetism of Rapidly Quenched Sm_1-xZr_xCo₅ Nanocrystalline Materials

Authors

Wenyong Zhang, University of Nebraska-LincolnFollow
Shah R. Valloppilly, University of Nebraska-LincolnFollow
Xingzhong LI, Nebraska Center for Materials and NanoscienceFollow
Yi Liu, University of Nebraska-LincolnFollow
Steven A. Michalski, University of Nebraska-LincolnFollow
Thomas A. George, University of Nebraska-LincolnFollow
Ralph Skomski, University of Nebraska-LincolnFollow
Jeffrey E. Shield, University of Nebraska-LincolnFollow
David J. Sellmyer, University of Nebraska-LincolnFollow

Date of this Version

7-2013

Citation

IEEE TRANSACTIONS ON MAGNETICS, VOL. 49, NO. 7, JULY 2013; doi: 10.1109/TMAG.2013.2240440

Comments

Copyright 2013 IEEE. Used by permission.

Abstract

The effect of Zr addition on nanostructure and magnetic properties in nanocrystalline Sm_1-xZr_x Co₅ (x = 0 – 0.6) has been investigated. (Sm, Zr)Co₅ with the CaCu₅ structure was synthesized by melt spinning. The lattice parameters a and b decrease with x, whereas c increases. Thus, the unit cell volume of (Sm, Zr)Co₅ shrinks because the smaller Zr atoms occupy the sites of the larger Sm atoms. Zr addition decreases the grain size and induces the formation of planar defects. The coercivity decreases with x, due to weakening of magnetocrystalline anisotropy energy and effective intergrain exchange coupling. A very high coercivity of 39 kOe and energy product of 13.9 MGOe are obtained for x = 0. The remanence of (Sm, Zr)Co₅ increases with x. For ≤ 0.4, the energy product slightly decreases with x. The results show that 40% of the Sm can be replaced by the less expensive Zr, with an energy-product reduction of only 10%. In addition, the planar defects are responsible for the change of coercivity mechanism from the nucleation-type of reverse domain for the x = 0 to the pinning-type of domain wall for the x = 0.4.