Influence of the Quenching Process on the Local Structure and Thermoelectric Properties of Polycrystalline LaCoO3

We succeeded in synthesizing polycrystalline LaCoO3 using the solid-state method which was then carried out various heat treatments with and without a quenching process. The powder X-ray diffraction spectrum shows that the peak formed is LaCoO3 with a rhombohedral crystal structure with the space group $R-3 C$. The results of the Rietveld refinement exhibit the sample that underwent the quenching process $(Q)$ produced a cell volume that was larger than that without quenching (NQ). For distances and angle bonding on the NQ sample, it is $1.9342(17)$ Å and $163.8(7)^{\circ}$, while for the sample Q, it is $1.93386(0)$ Å and $163.8023(0)^{\circ}$, respectively. The particle sizes of both samples are in the order of $\mu \mathrm{m}$-units. The EDX measurement results show that the ratio between the La and C0 elements is slightly non-stoichiometric. The quenching process causes a slight decrease in resistivity which has a direct impact on increasing the $P F$ value. The largest $P F$ of Q and NQ samples is about $0.0398 \mathrm{~mW} / \mathrm{mK}^{2}$ and $0.0317 \mathrm{~mW} / \mathrm{mK}^{2}$, respectively.