ESR SPECTROSCOPY ON GLASSES AND GLASSY-CRYSTALLINE MATERIALS - NEW OPPORTUNITIES FOR MATERIAL SCIENTISTS

Analyzing the state of the art of ESR applied to glasses, one can stat e that all results obtained so far give evidence for the fact that the electron (and nuclear) spin properties are related in a unique manner to the local properties of glassy systems. Therefore, all spin-derive d experimental parameters obtained for non-crystalline solids are disp ersed around mean values. Suitable theoretical models for an adequate representation of the complex ESR spectra of glasses are reviewed and critically analyzed. The information about the glassy state of matter generated with the help of paramagnetic species offers new opportuniti es for material scientists: criteria for the homogeneity, devitrificat ion and crystallization of glasses on a microscopic level; indication of redox processes; localization and function of dopants and their eff ect on the material properties; evidence for different kinds of intern al strain. Some relevant, up to now not commonly used methodical ESR d evelopments like in-situ bending stress experiments, tomography, wide range (4 K less-than-or-equal-to T less-than-or-equal-to 1000 K) tempe rature dependence are presented.