Rachmat Triandi Tjahjanto, Safira Firdausi, Masruroh
This study examines how the heating rate at calcination temperature (5 °C/min, 10 °C/min, 15 °C/min, and 20 °C/min) on the synthesis of Ca3Co4O9 (CCO) material using soft template (rice starch) affects the thermal conductivity (κ), electrical resistivity (ρ), particle size, and crystallite size in addition to the Ca3Co4O9 phase. The sol-gel combustion method uses the precursor compounds CaCO3, Ca(NO3)2∙4H2O, and Co(NO3)2·6H2O. The Rietveld refinement technique verified the crystal structure, and the Williamson-Hall (WH) plot was used to calculate crystallite size. The heating rate variations were related to the phase transition, reaction rate, and combustion energy that affected the crystal size and p-type thermoelectric (TE) capabilities. Using calcium nitrate as the precursor yields a higher purity of CCO than calcium carbonate. With an increase in heating rate temperature, the values of κ and ρ tend to rise; they vary from 1.7414 to 1.9827 W/m·K and 90.8222–194.1667 mΩ cm, respectively. The occurrence of CaCO3 in the final product and the anomaly of crystallite size at 20 °C/min are discussed. © 2024 Elsevier Ltd and Techna Group S.r.l.
Chemistry Department, Brawijaya University, East Java, Malang City, 65145, Indonesia; Physics Department, Brawijaya University, East Java, Malang City, 65145, Indonesia
