Abstract:
The epr of Fe3- and Gd3- in single crystals of Na2Zn(S04)24H20 was studied at liquid nitrogen temperature using a Q band spectrometer. For each ion, two spectra superimposed in the (010) plane and along b were observed. The spectra were described by the most general spin Hamiltonian, the constants of which were obtained for both ions. Analysing the pseudo-symmetry of the fourth-order term of the spin Hamiltonian, it is found that Fe3- only modifies the orientation of the local structure slightly and that the charge defect is probably balanced by a Na- vacancy. It is shown that the local structure around Gd3- is very different from the one around Fe3-. © 1986 The Institute of Physics.