An EPR study of neutron-irradiated CaO. Observation of the molecular ion OH2-
- 7 June 1975
- journal article
- Published by IOP Publishing in Journal of Physics C: Solid State Physics
- Vol. 8 (11) , 1718-1730
- https://doi.org/10.1088/0022-3719/8/11/023
Abstract
Two previously unreported EPR spectra have been observed from defects in neutron-irradiated CaO. The first spectrum consists of a single isotropic line with no apparent structure at g=2.0051. The second spectrum is described using spin Hamiltonians with S=1/2 and I=1/2. At room temperature the spin Hamiltonian has axial symmetry, but at 77K it is orthorhombic. By considering the behaviour of the spectrum at intermediate temperatures it is shown that the higher-temperature spectrum is due to a defect which is moving in the lattice, thereby averaging an otherwise orthorhombic Hamiltonian. The activation energy for this reorientation is found to be approximately 0.13 eV. A detailed model is presented to explain the observed spectra, involving the molecular ion OH2- at an anion site.Keywords
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