Paramagnetic Defects in High-Purity Quartz and Cristobalite Grits after Various Stages of Purification

High-purity quartz and cristobalite grits were obtained using the dressing technology of quartzite from the Eastern Sayan. Electron paramagnetic resonance (EPR) of structural impurities and defects in the fast-electron-irradiated samples of quartzite grits after various stages of their enrichment has been studied. A computer simulation of complex EPR spectra was performed to clarify the nature of structural impurities and point defects. From EPR studies, it was found that structural germanium impurities are observed as five different paramagnetic centers (PCs) associated with the vacancy of an oxygen atom or with Li and Na atoms in structural c -channels. After calcination of quartz concentrates, the formed cristobalite inherited Ge and Al isomorphic impurities with modified spin Hamiltonian parameters of the EPR spectra. Paramagnetic defects similar to E' γ , E' α1 , E' δ centers were observed in pure cristobalite. Additionally, a new Ge E' δ center was detected in quartz-cristobalite concentrate with structural impurities of germanium.