ELECTRON-PARAMAGNETIC-RESONANCE OF TITANIUM IMPURITIES IN REDUCED YTTRIA-STABILIZED ZIRCONIA

The electronic defects in single crystals of yttria-stabilized zirconi a (YSZ) have been examined using electron paramagnetic resonance (EPR) . The EPR spectra of hydrogen-reduced YSZ single crystals are almost i dentical to those of polycrytstalline yttria (12 mol%)-stabilized zirc onia-titania, indicating that the Ti3+ cation is the predominant elect ronic defect in both materials. The disparity between the discoloratio n of the polycrystals and single crystals (blue vs yellow) is attribut ed to the different crystalline environments of the Ti3+ cations in th e grain boundaries and lattice. The concentration of titanium cations in the YSZ single crystals (ca. 600 ppm) is probably too dilute to con tribute to the electronic conductivity.