EPR Spectra of Gd3+-Doped NdCl3·6H2O and PrCl3·7H2O

The paramagnetic resonance spectra of Gd3+-doped NdCl3·6 H2O and PrCl3·7 H2O single crystals are studied at room temperature. A six-line spectrum for H ‖ Z and a seven-line spectrum for H ‖ X corresponding to ΔM=±1 transitions, are observed in the case of Gd3+-doped NdCl3·6 H2O, whereas Gd3+-doped PrCl3·7 H2O shows a seven-line spectrum for H ‖ Z as well as for H ‖ X. The absence of the seventh line in the case of Gd3+-doped NdCl3·6 H2O for H ‖ Z spectrum is explained as due to large zero-field splitting between ±52 and ±72 levels. The angular variation of the observed spectra in ZX plane from θ=0° to θ=90° is studied and the spin-Hamiltonian analysis is presented. A number of lines have been observed in the low-field region in the case of Gd3+-doped PrCl3·7 H2O and they have been analyzed as due to transitions with ΔM>1.