## 4 Results and Discussion
### Thermogravimetric Analysis (TGA/DTG)
The conversion of magnetite to hematite under oxidizing conditions and vice versa under reducing conditions can indicate whether the ceramics were fired in an oxidizing or reducing atmosphere. Furthermore, the use of magnetite as a stable phase for producing a black pigment can influence the final color of the ceramic samples, highlighting the significant impact of firing conditions on the overall appearance and aesthetics of the finished ceramics [48]. These findings suggest that the physical accidents observed in some pieces, such as circular exfoliation due to the sudden evaporation of water, may be attributed to the dehydration processes occurring at different temperature ranges during the firing of the ceramics. This process is similar to exfoliation in rocks, where tension from water entering cracks leads to the formation of new low-density minerals, enhancing cracks and causing slabs to detach. The TGA curves of the investigated samples show a total mass loss (ML) of the samples ranging from 1.17 mg to 5.63 mg, as can be seen in Figure 8. The decomposition process occurred within the temperature ranges of room temperature (RT) to 220 \({}^{\circ}\)C, 220 to 600 \({}^{\circ}\)C, and 600 to 700 \({}^{\circ}\)C. During the initial temperature range of RT to 100 \({}^{\circ}\)C, the dehydration of hygroscopic water (humidity) resulted in a mass loss change from 0.1 to 1.3%. Between 100 and 220 \({}^{\circ}\)C, the dehydration of phyllosilicate minerals took place. The thermal analysis results shown in Figure 8 indicate that the total mass loss (ML) of the studied samples varied from 1.17 mg (sample P1) to 5.63 mg (sample P2). The initial loss of mass of up to 120 \({}^{\circ}\)C is likely due to the removal of adsorbed water, which is typically present in the form of hygroscopic phases that form during the setting and hardening processes of hydraulic binders. This water is strongly bound to the surface of the particles and can be easily removed through evaporation. The loss of mass in the temperature range of 120-200 \({}^{\circ}\)C is likely due to the loss of water from crystallization from hydrated salts, such as gypsum, which is a common component in many cement-based materials. The thermal decomposition of the samples was observed to occur in three temperature ranges: room temperature (RT) to 220 \({}^{\circ}\)C, 220 to 600 \({}^{\circ}\)C, and 600 to 700 \({}^{\circ}\)C. Within the RT to 220 \({}^{\circ}\)C range, the mass loss (ML) can be further divided into two ranges: RT to 100 \({}^{\circ}\)C and 100 to 200 \({}^{\circ}\)C. These findings suggest the presence of different components or phases within the samples that exhibit distinct thermal decomposition behaviors at different temperature ranges. The dehydration of hygroscopic water (humidity) occurs between RT and 100 \({}^{\circ}\)C [4; 13], accompanied by an ML change from 0.2 to 1.6%. After that, in the range of 100-220 \({}^{\circ}\)C, the dehydration of phyllosilicate takes place [59; 60; 61; 62]. The mass loss between 200-600 \({}^{\circ}\)C is likely due to the dehydration of calcium sulfate hydrates (CSHs), as there is no evidence of other hydrated substances decomposing in this temperature range. This suggests that the loss of mass is primarily caused by the removal of water molecules from the crystal structure of the hydrates, rather than any other decomposition reactions. Above 600 \({}^{\circ}\)C, the mass loss is likely due to the decomposition of carbonates present in the sample [63]. The highest mass loss observed in sample P2 is likely due to the decomposition of carbonates, which is consistent with the loss on ignition (LOI) analysis. The high mass loss in sample P2 is likely due to the decomposition of these carbonate minerals, which releases CO\({}_{2}\) gas and causes a significant increase in mass loss (Figure 8). According to [PERSON] et al.