Electron spin resonance of donor centers in beryllium oxide

The ESR spectra of two deep centers found in irradiated BeO crystals and powders, respectively, are reported and analyzed. They are due to electrons trapped at substitutional boron (B+++) and fluorine (F-) ions as concluded from the hf interaction of the unpaired electron with the respective nuclei. The boron center revealed a static, the fluorine center a dynamic Jahn-Teller effect between 77°K and 300°K. In both cases, the unpaired electron was found to be localized in nonaxial orbitals, which is shown to be consistent with the direction of the polar field of the crystal structure. The strong localisation of the electron is contrasted to the behavior of donor electrons in other II-VI compounds, which are highly delocalized. © 1965 Springer-Verlag.