ESR spectroscopy on glasses and glassy-crystalline materials - New opportunities for material scientists

Abstract

Analyzing the state of the art of ESR applied to glasses, one can state 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-derived experimental parameters obtained for non-crystalline solids are dispersed 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 opportunities for material sciendsts: criteria for the homogeneity, devitrification and crystallizadon of glasses on a microscopic level; indication of redox processes; localization and function of dopants and their effect on the material properties; evidence for different kinds of internal strain. Some relevant, up to now not commonly used methodical ESR developments like in-situ bending stress experiments, tomography, wide range (4 K ≤ T ≤ 1000 K ) temperature dependence are presented.