Investigation of radiation-induced interstitials in RbCaF3

Electron spin resonance studies of fluorine interstitials were performed on the perovskite-structured RbCaF3. Intrinsic fluorine interstitial (H) centers were induced in this material at 77 K by irradiation with 1.5 MeV electrons from a Van de Graaff accelerator. The ESR spectrometer employed was an X-band homodyne system. Intrinsic and perturbed fluorine interstitials were observed. The intrinsic center was stable below 110 K while the perturbed center started to appear at 110 K and decayed after 150 K. From experimental data taken, defect models for both intrinsic and perturbed centers were determined. It was concluded that both intrinsic and perturbed centers consisted of two fluorines, the intrinsic (H) center being aligned along the [001] unique axis and the perturbed (H/sub A/) center axis making an angle of 11.90 with this [001] direction. Spin Hamiltonian parameters were determined for both centers by rigorous computer diagonalization of the complex Hermitian matrix obtained by the use of an appropriate spin Hamiltonian