EFFECT OF COPPER SUBSTITUTION ON THE ELECTRICAL TRANSPORT-PROPERTIES OF (BI,PB)2MO4 (M = PD, PT) LINEAR-CHAIN COMPOUNDS

Three extensive new solid solution series were prepared in which M2+ (M = Pd, Pt) is replaced by Cu2+ in the unoxidized Bi2PdO4 and in the partially oxidized (Bi,Pb)2MO4 phases. For palladium compounds, the tetragonal cell c parameter and therefore the metal-metal distance decreases with increasing copper substitution, while for platinum-based materials, the M - M distance increases with increasing copper concentration. However, for the three series, the resistivity regularly decreases with Cu2+ substitution for M2+. Thus, by adjusting both the [Bi]/[Pb] and [M]/[Cu] ratios it is possible to obtain a material with a given room-temperature conductivity ranging from 10 to 10(-6) S cm-1.