Electron spin echo envelope modulation spectroscopy in mixed alkali silicate glasses

Abstract

Lithium and sodiumsilicate glasses of the x mole % Li 2 O y mole % Na 2 O (100-x-y) mole % SiO 2 composition with x, y between 10–50 were γ-irradiated at room temperature and subsequently studied by electron spin echo envelope modulation (ESEEM) spectroscopy at the X-band and 20 K temperature. Evaluation of the ESEEM spectra revealed weak magnetic coupling between the nonbridging oxygen (NBO) and the neighboring alkali metal. The covalent character between NBO and alkali metal is negligible, though it depends upon the kind weakly. The alkali metal occupies sites forming an angle of 60° with respect to the z-axis of the g-tensor. The magnetic couplings remain unchanged with the variation of the concentration of the alkali or the doping with another alkali.