MAGNETIC ENTROPY CHANGE AND HYSTERESIS EFFECT IN LA(FE,SI,M)_(13) (M=CU, GA) SYSTEMS

摘要

The magnetic properties, magnetic entropy change and hysteresis loss in La(Fe,Si,M)_(13) (M=Cu, Ga) compounds were investigated. It was found that the LaFe_(11.7)(Si_(1-x)Cu_x)_(1.3) and LaFe_(11.5)(Si_(1-y)Ga_y)_(1.5) compounds retain the cubic NaZn_(13) structure when the substitution of Cu for Si or Ga for Si reaches 20%, 15%, respectively. With increasing Cu or Ga content, Curie temperature T_C increases, metamagnetic behavior becomes weaker and magnetic entropy change |△S_m| drops. However, |△S_m| of LaFe_(11.7)(Si_(1-x)Cu_x)_(1.3) still remains a large value, ～20 J/kg K, when Cu content x reaches 0.2. An attractive feature is that both thermal and magnetic hysteresis can be remarkably reduced by introducing Cu or Ga. The maximum hysteresis loss at T_C drops from 74.1 J /kg to zero when the substitution of Cu for Si increases from 0 to 20%.