EFFECT OF NIOBIA ON THE DEFECT STRUCTURE OF YTTRIA-STABILIZED ZIRCONIA

Up to 1.0 mol% Nb2O5 was added to 9 mol% Y2O3-stabilized ZrO2. The bul k resistivities were measured by the complex impedance approach, the a dditions of Nb2O5-were found to increase the resistivities. The defect structure change caused by the additions of Nb2O5 was studied by the positron annihilation technique (PAT), it was found that the additions of Nb2O5 can decrease rite V-O over double dot concentration and incr ease the (Y'V-Zr(O) over double dot Y'(Zr))(x) concentration, and poss ibly decrease the mobility of V-O over double dot, which explains the increasing bulk resistivities. The additions of Nb2O5 are expected to suppress the formation of defect associates, however, only adverse exp erimental results were found, suggesting that such kind of defect reac tions are impossible in the low Nb2O5 concentration of the present wor k. (C) 1997 Elsevier Science Limited.