Enhanced Electron Correlation in the In‐doped Misfit‐Layered Cobaltite <scp> <scp>Ca</scp> </scp> ₃ <scp> <scp>Co</scp> </scp> ₄ <scp> <scp>O</scp> </scp> ₉ Ceramics

Abstract

The structural, magnetic, electrical and thermal transport properties of the polycrystalline samples Ca 3 Co 4− x In x O 9 ( x = 0, 0.05, 0.10, 0.15, and 0.20) have been investigated systematically. The results indicate that the In‐substitution has a negative effect on the low‐temperature ferrimagnetic transition and the propagation of spin‐density‐wave. All In‐doped samples have a much larger resistivity than that of the un‐doped sample. And the temperature region where the Fermi liquid transport mechanism dominates is remarkably widened via In‐doping. However, for the In‐doped samples, as the In‐doped content increases, the value of resistivity ρ decreases monotonously and the electronic correlation in the system enhances. With the addition of In‐ions in Ca 3 Co 4 O 9 system, the thermopower S and the ZT value decrease. The results are suggested to originate from the variations of carrier concentration and lattice disharmony in this system induced by In‐doping.