EPR of Gd3+ in Sulfate Host Crystals of Low Symmetry

Abstract

Abstract Electron paramagnetic resonance (EPR) spectra of trivalent gadolinium have been investigated in orthorhombic sulfate host crystals MeSO4 with Me = Sr, Ba, Cd, Hg, Pb and K2SO4 . Because of the low symmetry of the host crystals and the spin quantum number 7/2, complex spectra for several orientations of the magnetic field containing a large number of individual lines had to be analyzed. The spin Hamiltonian parameters have been rigorously determined from the rotational diagrams. Gd3+ has been found to substitute, first of all, for the monoclinic sites of the host metal ion with charge compensation at larger distances. To a small extent, charge compensation in the vicinity has also been observed, arising from additional centres and spectra with lower intensities. Correlations between EPR spectra and crystal structure are reflected in the values of the zero field splitting parameters.