Electron paramagnetic resonance of Ce3+ in strontium-barium niobate

The EPR of Ce3+ in congruent SrXBa1-xNb2O6 (x = 0.61) is characterized by the orthorhombic g-tensor {0.89, 3.55, 0.54} with principal axes lying in the c-plane, tilted with respect to the a- and b-axes by 21.1 degrees: and along the c-axis. Ce3+ occupies a single crystallographic site in the crystal, leading to a unique EPR spectrum. The point symmetry of the Ce3+ position, C-1, is lower than that of the replaced alkaline-earth ions, C-4 or C-s. This is attributed to an off-centre movement of Ce3+. The Ce3+ signal decreases under illumination. No further EPR signal is detected to arise from the photoionization of Ce3+.