Effects of phase Separation and devitrification processes in oxide glasses on ESR spectra

Abstract

The consequences of phase Separation and devitrification processes for the ESR patterns of Fe³⁺ ions and oxygen hole centres in giassy and glassy-crystalline Systems are discussed. Analysis of the Fe³⁺ spectra by Simulation (including 4th order terms) allows their model-based Interpretation for homogeneous, phase-separated and devitrified samples as well. It is even possible to estimate the ratio of Fe³⁺ ions incorporated into the giassy matrix to those localized in the crystalline phase. An influence of irreversible structural reorganization in glasses on γ-irradiation-induced oxygen hole centres is detectable by studying their Saturation behaviour For the example of a barium Silicate glass studied here, pronounced passage effects could be detected at 77 K. In contrast, a devitrified sample of the same composition after γ Irradiation yielded the same spectral pattern at low microwave power, but only Saturation broadening was to be observed when rising the microwave power. In an annealed sample of anorthite composition (in mol%: 25CaO, 25AI₂O₃, 50SiO₂) progressive crystal growth was detectable using Fe³⁺ ions as probes.