Effect of Y-doping on the phase relation and electrical properties of Fe-doped BaZrO₃

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>The effects of the co-doping of Y in Fe-doped BaZrO<SUB>3</SUB> (BaZr<SUB>0.7-<I>y</I> </SUB>Fe<SUB>0.3</SUB>Y<I> <SUB>y</SUB> </I>O<SUB>3-</SUB> <I> <SUB>δ</SUB> </I>) on the phase relation and electrical properties are investigated in this study. While a single phase is formed up to <I>y</I> =0.1 by the substitution of Y for Zr-sites (phase-1), the amphoteric substitution of Y for both Zr-sites and Ba-site (phase-2) is observed above <I>y</I> =0.1. Electrical conductivity measurements suggest that <I>p</I>-type conduction prevails under an oxidizing atmosphere. The hole conductivity increases with an increase of Y concentration up to <I>y</I> =0.1, but a further increase of Y concentration causes a decrease in the conductivity. The maximum conductivities of both bulk and grain boundary are obtained at <I>y</I> =0.1, and a further increase of Y concentration leads to a decrease of the conductivity due to the possible formation of phase-2 with the partial replacement of Y for Ba-sites ( Y B a • ). Partial proton conductivity is also improved by Y-doping up to <I>y</I> =0.1, but a further doping cannot contribute to an increase in the proton conductivity. The results indicate that the mixed proton and hole conductivity of Fe-doped BaZrO<SUB>3</SUB> can be improved by the co-doping of a rare-earth acceptor (Y<SUP>3+</SUP>), but the doping level is limited to <I>y</I> =0.1 to avoid the formation of phase-2.</P>