摘要
The Curie temperature of(Nd_(1-x)Pr_x)_2Fe_(14)Co_yB compounds(x=0,0.2,…,1.0 and y=O,2,4,6,14)has been determined with AC initial susceptibility measurement.It was found that the variations of Curie tempera- ture with x is not linear for y=0 and 14,whereas it is linear for other values of y.The lattice constants of (Nd_(1-x)Pr_x)_2Fet_(14)B were determined by using X-ray diffraction.The lattice expansion was mostly along the c axis,whereas that along the a-axis remained practically zero for the whole series.It is suggested that Pr atoms may show site preference in R_2M_(14)B compounds(M=Fe or Co).Due to the substitution of Co for Fe.the tendency of site preference of Pr becomes less pronounced,which may be attributed to the decrease of differ- ence of crystal electric field(CEF)acting on the two rare earth sites with the introduction of Co or Fe.In con- trast to that of the Pr atoms,the site preference of Co iu(Nd(1-x)Pr_x)_2Fe(14-y)Co_yB compounds does not depend on the composition of the rare earth sublattice(R=N d or Pr).
The Curie temperature of(Nd_(1-x)Pr_x)_2Fe_(14)Co_yB compounds(x=0,0.2,…,1.0 and y=O,2,4,6,14)has been determined with AC initial susceptibility measurement.It was found that the variations of Curie tempera- ture with x is not linear for y=0 and 14,whereas it is linear for other values of y.The lattice constants of (Nd_(1-x)Pr_x)_2Fet_(14)B were determined by using X-ray diffraction.The lattice expansion was mostly along the c axis,whereas that along the a-axis remained practically zero for the whole series.It is suggested that Pr atoms may show site preference in R_2M_(14)B compounds(M=Fe or Co).Due to the substitution of Co for Fe.the tendency of site preference of Pr becomes less pronounced,which may be attributed to the decrease of differ- ence of crystal electric field(CEF)acting on the two rare earth sites with the introduction of Co or Fe.In con- trast to that of the Pr atoms,the site preference of Co iu(Nd(1-x)Pr_x)_2Fe(14-y)Co_yB compounds does not depend on the composition of the rare earth sublattice(R=N d or Pr).
基金
This work was partly supported by National Science Foundation(No.5870025)
Magnetism Laboratory,Institute of Physics,Academia Sinica,Bejing,P.R.China.
