A Structural, Magnetic and Mössbauer Study of Tb0.3Dy0.7(Fe1−xAl x )1.95 Alloys

A structural, magnetic and Mossbauer study of a series of Tb0.3Dy0.7(Fe1−xAl x )1.95 alloys (x=0, 0.05, 0.1, 0.15, 0.20, 0.25, 0.30, 0.35) at room temperature is presented. It was found that the primary phase of the Tb0.3Dy0.7(Fe1−xAl x )1.95 alloys is the MgCu2-type cubic Laves phase structure when x<0.3 and a small amount of a second phase, RFe3 (R: rare-earth element), is present when 0.3≤x≤0.35. The lattice constant of the Tb0.3Dy0.7(Fe1−xAl x )1.95 alloys increases approximately monotonically with increasing x. The substitution of Al increases slightly the magnetostriction in a low magnetic field (H≤500 Oe). However, the magnetostriction decreases sharply, but is saturated more easily with increasing x in a higher applied field. The analysis of the Mossbauer spectra allows the determination of the easy axes of magnetization in these alloys. Moreover, the dependence of the hyperfine-field, isomer shift and quadrupole splitting on the Al concentration, x, for the Tb0.3Dy0.7(Fe1−xAl x )1.95 alloys are reported and discussed.