Electron spin resonance study of Mo centers in YAlO3

Electron spin resonance measurements of Ce-doped YAlO₃ single crystals (40–50 ppm of Ce) grown by Czochralski method from Molybdenum crucibles evidenced two kinds of Mo³⁺ centers. The ESR spectra of both centers were described by spin Hamiltonian with orthorhombic symmetry and an effective electron spin . The experimental g-factors as well as four magnetically nonequivalent positions found for each center support a hypothesis that Mo impurity ion is located at Al site. Under high-temperature annealing and UV irradiation the Mo centers show the change of charge state, indicating, that they are probably involved in the charge carrier capture in the energy transfer and storage processes in this scintillator material.