Thermoelectric properties of lower concentration K-doped Ca3Co4O9 ceramics
Li Ya-Nan1, Wu Ping1, †, Zhang Shi-Ping1, Chen Sen1, Yan Dan1, Yang Jin-Guang1, Wang Li2, Huai Xiu-Lan3
       

SEM images of sintered sample surfaces (a) Ca3Co4O9, (b) Ca2.95K0.05Co4O9, (c) Ca2.90K0.10Co4O9, and (d) Ca2.85K0.15Co4O9.