PREPARATION OF Y3NBO7 POWDERS WITH EXCESS OXYGEN VACANCIES AND CONDUCTIVITY OF THE SINTERED BODIES

Y3NbO7 powders with excess oxygen vacancies were prepared by calcining coprecipitated powders of (YO1.5)1-x(NbO2.5)x(x=0.20-0.30) at 1200-de grees-C in an Ar gas flow, which was synthesized from YCl3 and NbCl5 u sing the liquid phase coprecipitation method. Also number of oxygen va cancies in the synthesized powders was estimated from the density, and conductivity of the resulting sintered bodies was measured. The numbe r of oxygen vacancies in the Y3NbO7 powder in the x=0.25 composition s ynthesized in Ar was around 1.48 in unit cell even after heat treatmen t in air. The number of oxygen vacancies in the x=0.20 and 0.30 compos itions synthesized in air increased by the change of valence number in Nb. On the other hand, after synthesizing the powder comprised of the x=0.20 composition in Ar, the number of oxygen vacancy of the powder reheated in air was 2.06. The conductivity of sintered bodies fabricat ed from the Y3NbO7 powders synthesized in Ar was raised by a half digi t higher than that of the sintered body fabricated from the powders sy nthesized in air. The conductivity of the sintered bodies obtained fro m the synthesized powders increased almost linearly with an increase i n the number of oxygen vacancies. Therefore, it was found that the int roduction of oxygen vacancies by controlling composition and the powde r preparation was an important factor for increasing in conductivity o f Y3NbO7 sintered body.