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 deg., 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, C1, is lower than that of the replaced alkaline-earth ions, C4 or Cs. 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+. (author)