Electron paramagnetic resonance or rare earth ions in calcia stabilized zirconia: Gd³⁺and Yb³⁺

The paramagnetic resonance spectra of Gd 3+ and Yb 3+ in annealed single crystals of calcia stabilized zirconia have been investigated in the X band. In both cases, sites of almost cubic symmetry with a weak axial deformation, the principal axis of which is directed along a (100) direction, were observed. Hyperfine structure for the two odd isotopes was resolved with A 171 =2701+or-10 MHz and A 173 =738+or-10 MHz. The authors results support the conclusions of Carter and Roth concerning the existence of a disorder-order transformation of calcia stabilized zirconia by annealing at 1000 degrees C, and confirm the ordered arrangement they proposed for the O 2- ions around the zirconium sites. The atomic arrangement and the presence of Ca 2+ ions and oxygen vacancies near the defects can account for the anomalous linewidths observed.