ELECTRON PARAMAGNETIC RESONANCE SPECTRA OF Gd(III) IONS IN SILICA AND GERMANIA SOL-GELS

摘要

The results of the EPR spectra of Gd(III) ions in silica and germania gels are presented. The observed spectra are typical of the so-called "U" spectra consisting of three essential features with effective g-values at ～2.02, 2.83 and 5.6 and weaker features at g = 3.6 and 4.3 Remarkable changes were observed in the EPR spectrum for the heat treated silica gels. The evolution of the U-spectra shows that the local order around the rare-earth ions is essentially dictated by the ion itself, and occupy sites surrounded by polyhedra of more or less irregularly distributed ligands with high coordination number ≥ 6.