Mossbauer studies of amorphous Fe73.5Cu1Nb3Si13.5B9 alloy

This paper reports a Mossbauer study of amorphous Fe73.5Cu1Nb3Si13.5B9 alloy between 10 and 673 K. The Curie temperature Tc is found to be 620-+ 1 K. The temperature dependence of the reduced average hyperfine field can be explained on the basis of Handrich's model of amorphous ferromagnetism, in which the parameter delta, which measures fluctuations in the exchange interactions, is assumed to have a temperature dependence delta = 0.525+0.208t-0.55t2, where t is T/Tc.

At low temperatures, the average hyperfine filed H-eff(T) van be fitted to H-eff(0) (1-b3/2(T/Tc)3/2), with H-eff(0)=255-+1 kOe and b3/2=0.43 over a large temperature range (T/TcT/Tc>0.4). Above the Curie temperature Tc, an average quandrupole splitting value of about 0.44 mm/s is found. The temperature dependence of the isomer shift can be fitted within the harmonic approximation to a Debye model with a Debye temperature theta-D=255.6 K.