M. Drache et al., Structural and conductivity properties of Bi(0.775)Ln(0.225) O-1.5 oxide conductors (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy) with rhombohedral Bi-Sr-O type, J SOL ST CH, 142(2), 1999, pp. 349-359
This paper deals with structural and conductivity properties of the dimorph
ic Bi(0.775)Ln(0.225)O(1.5) (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy) hexagonal
structure layer phases with rhombohedral Bi-Sr-O type, The evolutions, ver
sus Ln(VI)(3+) radius, of cell parameters, thermal expansion coefficients,
electrical properties (conductivity and activation energy), and structural
characteristics determined from Rietveld powder structure refinements, sugg
est two different domains (La-Sm) and (Gd-Dy), with the intermediate Eu sam
ple, thus possibly characterizing two kinds of ordering in the mixed cation
ic layer. The best conductivity properties obtained for Bi0.775La0.225O1.5
(sigma(400 degrees C) = 10(-3) S cm(-1) with E-a = 0.8 eV) are discussed an
d justified. (C) 1999 Academic Press.