Direct Measurement of the Oxygen Vacancies Produced in Calcium Tungstate by Fast Reactor Neutrons

Abstract

The present paper is intended to point out the usefulness of electron spin resonance for the direct measurement of defect concentration. Fast-neutron irradiation results in a variety of paramagnetic centers in calcium-tungstate single crystals. From the $g$ tensors, the hyperfine interaction, and the result of a uniaxial-stress experiment, one of the centers has been identified as due to paramagnetic tungsten associated with a displaced nearest-neighbor oxygen. The concentration of oxygen displacements is measured by comparison with a copper-sulfate standard and is calculated using the Kinchin-Pease theory. The measured and calculated values are in good agreement.