Structure and Conductivity of Pyrochlore and Fluorite Type Solid Solutions
نویسندگان
چکیده
High oxygen conductivities can be achieved in cation ordered LnxZrl_=O2_l x (Ln=Gd, Nd) solid solutions with pyrochlore (P) structure. High values of the pre-exponentlal factor °o are correlated with the degree of anion disorder in the 8b oxygen sublattice (neutron diffraction). The activation energy AH is lowered by cation ordering (F-P transition; effect of x) due to the occurence of a preferential diffusion path. Maximum oxygen conductivity is achieved in (l-x)Bi203-x Ln203 solid solutions with fluorite related 6-Bi203 structure for Ln = Er and x = 0.20. Neutron diffraction measurements indicate the occurrence of short range ordering in "Er-O units" with relative small interatomic distances at T < 820 K. This leads to an increased activation energy.
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