## 3 Results and Discussion
### The Firing Temperature Analysis Using SEM-EDS  
SEM-EDS provides valuable information on the pore structure and the glassy phase development and is used to study systematically the internal morphology changes occurring when the materials are fired in a temperature range of 600 \({}^{\circ}\)C to 1300 \({}^{\circ}\)C; it can be employed and coupled with Energy Dispersive Spectrometer (EDS) for minerals detection [73]. Scanning Electron Microscope is a vital tool for examining ancient pottery and establishing ancient ceramic technology [74]. It has been found useful in many applications to characterize archaeological artifacts [75; 76]. SEM with EDS analysis is non-destructive and capable of offering precise elemental composition information for the analysis of archaeological potsheds. The analysis evidences that the presence of Ca as tine-grained and evenly distributed calcite in clays significantly affects the development of vitrification if calcium present in the sample, say CaCO\({}_{3}\), dissociates into CaO and vitrification sets in around 850 \({}^{\circ}\)C.  
The non-calcareous clays fired at temperatures below 800 \({}^{\circ}\)C produce no vitrification [77]. However, well-crystallized hematite is abundant in non-calcareous clays. The absence of vitrification in the studied bricks is evidence of a firing temperature below 800 \({}^{\circ}\)C during manufacturing by artisans, as well evidenced by FTIR and XRD studies. Firing at 900 \({}^{\circ}\)C produces much more pronounced changes in the clay body; sintering is quite advanced, and much vitrification has been produced [73]. Ref. [78] stated that continuous heating activates densification, which leads to a reduction in porosity, and it could lead to the generation of residual porosity and initial grain growth. They also opined \begin{table}
\begin{tabular}{l l l l l} \hline \hline
**S.No.** & **Sample ID** & **Color** & **Type of the Clay** & **Estimation of Firing Temperature** \\ \hline
1 & Mouramora-1 & Light red color & White clay & Below 650 \({}^{\circ}\)C \\
2 & Mouramora-2 & Light red color & White clay & Below 650 \({}^{\circ}\)C \\
3 & Mouramora-3 & Light red color & White clay & Above \(-800\) \({}^{\circ}\)C \\
4 & Padum Pukhuri & Light red & White clay & Above \(-800\) \({}^{\circ}\)C \\
5 & Rukmini Garh & Reddish yellow & White clay & Above \(-800\) \({}^{\circ}\)C \\
6 & Pratima Garh & Weak red & Red clay & Above \(-800\) \({}^{\circ}\)C \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Estimation of firing temperature of studied brick samples based on FTIR and XRD analyses. that this process initially creates necks between particles, followed by developments of cylindrical shape, interconnected pores, and lastly, pores change to a more spherical and isolated state as temperature increases. The SEM micrographs of the studied samples show the presence of such micropores (Figure 6a,b), as well as change in pores shape to spherical and isolated state (Figure 6c-f), suggesting that the heating temperature increased in the bricks of Mouramora-3, Padum Pukhuri, Pratima Garh, and Rukmini Garh compared with the Mouramora-1 and Mouramora-2 bricks. The chemical composition of the samples was obtained using EDS analysis, and their representative spectra are shown in Figure 7. From the EDS analysis, the potshers mainly have high concentrations of silica (SiO\({}_{2}\)), alumina (Al\({}_{2}\)O\({}_{3}\)), and fluxes (Na\({}_{2}\)O, K\({}_{2}\)O, Fe\({}_{2}\)O\({}_{3}\), CaO, MgO and TiO\({}_{2}\)), as they were identified in all the samples except for Na\({}_{2}\)O, CaO,  
Figure 6: Representative SEM backscattered image of surface morphology of studied fired brick samples. (**a**) Mouramora-1, (**b**) Mouramora-2, (**c**) Mouramora-3, (**d**) PadumPukhuri, (**e**) Pratima Garh, (**f**) Rukmini Garh. and TiO\({}_{2}\) in Padum Pukhuri, CaO and TiO\({}_{2}\) in Mouramora 1, and CaO in Mouramora 2.