Evidence of spin-density-wave transition and enhanced thermoelectric properties in Ca3−xCexCo4O9+δ

Abstract

We have investigated the effect of Ce doping on the magnetic and low-temperature thermoelectric properties of Ca3Co4O9+δ. A small shoulder occurring at about 23 K in the dχ−1/dT curve indicates an occurrence of spin-density-wave transition, which is confirmed by resistance characteristics. With partial Ce substitution, the thermopower increases while the thermal conductivity decreases. The magnetic measurements give a support to the concentration reduction in Co4+ ions, which results in the enhancement of thermopower. The dimensionless figure of merit ZT=0.016 is achieved at 335 K for Ca2.9Ce0.1Co4O9+δ, demonstrating that heavy atoms Ce doping may promise an effective way for improving thermoelectric properties of Ca3Co4O9+δ system.