Effect of thermal neutrons on curie temperature and lattice parameter of yttrium-gadolinium ferrogarnets

The influence of the thermal (E∼0.25 eV) and fast (E ≥ 0.1 MeV) neutrons on Curie temperature Tc and the lattice parameter ''a'' of GdIG was studied. The dependence of the volume fraction of the disordered state Ct upon the irradiation dose of the thermal neutrons Φt was: Ct=1-exp(-βtΦt), where βt=2.5x10-20 cm2. The decrease in Tc was caused by the increase in ''a'' for Gd1.5Y1.5Fe5O12 and Gd3Fe5O12 ferrites. The fact has been described as the linear relation: ΔTc=-1250Δa k A-1 found earlier for the fast neutron irradiated YIG. This relation had also been observed during GdIG samples annealing. The X-ray analysis has provided for the possibility to separate the contribution of the thermal and fast neutrons