Characterization of nanocrystalline CuCo2O4 spinel prepared by sol–gel technique applicable to the SOFC interconnect coating

CuCo2O4 spinel nanopowders were synthesized by sol–gel method. The optimal values of pH and molar ratio of citric acid to metal ions (RC), and the influence of the calcination temperature and time were investigated. As-prepared materials were characterized by XRD, TGA, DSC, FE-SEM and electrical and coefficient of thermal expansion (CTE) measurements. It was found that pH = 4.5 and RC = 1 are the optimum conditions to produce pure CuCo2O4 nanopowders. The electrical conductivity was increased remarkably from 15.2 to 27.5 S cm−1 with an increase in temperature from 500 to 800 °C. Over the temperature range of 25–800 °C, the CTE of CuCo2O4 was 11.4 × 10−6 K−1 which is very close to the CTE of ferritic stainless steel (~12 × 10−6 K−1) used as solid oxide fuel cell interconnect.