Electron spin resonance of Gd3+ in triacetate tetrahydrates of Sm, Nd, Er, Y, Yb, and Dy

An EPR study of Gd3+-doped single crystals of triacetate tetrahydrates of Sm, Nd, Er, Y, Yb, and Dy has been made in order to study the systematics of EPR spectra in these homologous isostructural hosts at various temperatures. The absolute signs of the spin Hamiltonian parameters are determined from intensities of lines at liquid helium temperatures. The parameters are evaluated using a rigorous least-squares fitting procedure. As far as the systematics of the parameters are concerned, it is found that while the parameter b22 varies linearly, the parameter b02 varies approximately linearly with the atomic radius of the host rare-earth ion. The EPR studies presented here suggest a monoclinic symmetry at the site of the rare-earth ions in the rare-earth triacetate tetrahydrate crystals investigated. As well, all rare-earth sites are found to be magnetically equivalent. The EPR data also suggest that the Nd host undergoes some structural change at about 238 K.