Enhanced thermoelectric properties at x/spl sim/0.1 in La/sub 1-x/Sr/sub x/CoO/sub 3/ and La/sub 1-x/Sr/sub x/(Co/sub 1-y/M/sub y/)O/sub 3/ (M=Cr, Cu)

摘要

The thermoelectric properties of the La/sub 1-x/Sr/sub x/CoO/sub 3/ system have been investigated from 10 K to 300 K. The figure of merit Z and power factor P increase with increasing Sr concentration x and show a maximum for x=0.10-0.15, where the ferromagnetic (FM) order starts to appear. The maximum Z value (Z= 150 x 10/sup -6/ K/sup -1/ at 230 K for x=0.10) is larger than those of layered cobaltites. The Z and P values are enhanced by the 5 % Co-site substitution by Cr for the overdoped concentration (x=0.20), but are depressed for the nearly optimum doped one (x=0.15). The results are discussed in conjunction with the carrier density n of this system.