ABSTRACT
This research studies the effect of the heating rate at calcination temperature (2°C, 5°C, 10°C, and 20°C/min) on the Ca3Co4O9 phase and crystallite size, as well as the thermal conductivity (κ) and electrical resistivity (ρ) of the material. Co(NO3)2∙6H2O and CaCO3 synthesised by sol–gel combustion technique. The Rietveld refinement technique confirmed the structure and crystal size calculations were performed using the Williamson-Hall (WH) plot. Thermogravimetric-differential thermal analysis (TGA-DTA) showed differences in the exothermic energy produced (553–683 K), which related to the reaction rate and phase transitions affecting the crystal size and thermoelectric (TE) properties as the p-type TE material. The κ and ρ values tend to increase with increasing heating rate temperature, where κ and ρ values range from 1.69 to 1.90 W/mK and 82.73 to 118.57 mΩ cm respectively.
Acknowledgments
We want to thank Brawijaya University for funding most of this research.
Disclosure statement
No potential conflict of interest was reported by the author(s).