V. Thangadurai et W. Weppner, AA ' 2M3O10 (A = K, Rb, Cs; A ' = Ca; M = Nb) layered perovskites: low-temperature proton conductors in hydrogen atmospheres, J MAT CHEM, 11(2), 2001, pp. 636-639
Electrical conductivity of the Dion-Jacobson (D-J) type layered perovskite
oxides, AA(2)'M3O10 (A = K, Rb, Cs; A' = Ca; M = Nb, Ta), is determined by
AC impedance analysis in hydrogen atmospheres and in air. The electrical co
nductivity behavior of the layered perovskite oxides in hydrogen is differe
nt from that in air. Among the layered perovskites, KCa2Nb3O10 exhibits the
highest electrical conductivity, sigma, of 3.2 x 10(-4) S cm(-1) at 45 deg
reesC with an activation energy, E-a, of 0.25 eV in a hydrogen atmosphere.
Open circuit voltage measurements at room temperature with hydrogen-oxygen
gas concentration cells reveal that the mobile charge carriers are most lik
ely protonic in origin. The electrical (proton) conductivity is comparable
to that of fast lithium ionic conductors based on the perovskite structure
such as (Li,La)TiO3 at the same temperature.