Effect of impurities on sintering and conductivity of yttria-stabilized zirconia

Abstract

The effect of low concentrations of Fe203, AI203 and Bi203 on the sintering behaviour of (ZrO2)o.83 (YO1.s)o.17, made by alkoxide synthesis, has been investigated. The best results are achieved with Bi203 as a sinter agent and a relative density of 95% is obtained at 1200 K. The effects of these impurities on the electrical conductivity of the bulk and the grain boundaries has been investigated using frequency dispersion analysis (101-106 Hz). All investigated impurities have a negative influence on both the bulk and grainboundary conductivity. For Fe203 and AI203 grain-boundary segregation factors of about two are calculated.

Bulk and electrochemical properties of BiVO4

“…1 lower than the conductivity of YSZ [ 11 ]. It can be seen that at high temperatures especially the points for low Po2 values deviate from a single straight line.…”

Preparation and electrical properties of a monophasic ZrO2Y2O3Bi2O3 solid electrolyte

“…The ~nhomogeneous Bi-doped Zr-Y materials, which contain a monoclinic phase, show a decrease in conductivity compared with the Bifree samples [2,8]. A ZY17 sample doped with 2.2 mol% Bi203, which contains 20 mol% monocTinic ZrO 2, shows a large depression of the grain boundary semicircle in the complex impedance diagram [8].…”

“…This resulted in the ternary system ZrO2-Y203-Bi203 [2,7,8]. A decrease from 1520 K to 1200 K is found in T S if BipOR is introduced into asinter-reactive ZY17 powder by dry milling [8]. In ~o~t cases however a monoclinic ZrO 2 phase appears when Bi203 is introduced into ZrO2-Y20 R. The presence of a monoclinic phase with low conductivity decreases the 6e~hanical stability and causes deterioration of some of the sensor functions [9,10].…”

“…This resulted in the ternary system ZrO2-Y203-Bi203 [2,7,8]. A decrease from 1520 K to 1200 K is found in T S if BipOR is introduced into asinter-reactive ZY17 powder by dry milling [8].…”

Electrical and catalytic properties of some oxides with the fluorite or pyrochlore structure

“…Substantial enrichment of the surface with Bi in Bi-doped compounds has been shown previously in doped zirconia [ii] and in doped scheelites [12]. The improvement of oxygen transfer, ascribed to Bi 3+ ions [13], is reflected in the very low order in 02 , indicating a fast reoxidation of the surface of Bi3+-doped titanates.…”