## 3 Results and Discussion
### Thermal Analyses  
The thermal analyses (differential thermal analysis--DTA; differential thermal gravimetric--DTG; and thermal gravimetric analysis--TGA) of the prepared materials were measured in the presence of both nitrogen gas and air to indicate the oxidation reactions of the divalent cations (cobalt and tin) and the cyanate anions. Figure 8a shows the thermal analyses of CSHDS in the presence of nitrogen. The TGA curve shows the total weight loss that occurred throughout the two stages. Figure 7: FT-IR spectra of: (**a**) CSHDS, (**b**) CSLDH-1, and (**c**) CSLDH-2. In the first stage, the water was lost through three steps [38]. It was found that 4.6 wt.%, 7 wt.% and 8.3 wt.% were lost at 107 \({}^{\circ}\)C, 150 \({}^{\circ}\)C and 191 \({}^{\circ}\)C, respectively. These losses were confirmed by DTG and DTA. DTA showed two endothermic peaks at 70 \({}^{\circ}\)C and 133 \({}^{\circ}\)C. It means that the water molecules are bonded in the lattice by two different species--nitrate and cyanate anions [14; 15]. In the second stage, 11.7 wt.% was lost, indicating the removal of the interlayered anions at 281 \({}^{\circ}\)C. The thermal decomposition of the interlayered anions was confirmed by two endothermic peaks at 218 \({}^{\circ}\)C and 265 \({}^{\circ}\)C in the DTA curve. It means that there are two anions in the lattice of CSHDS. By measuring the thermal analyses in presence of oxygen, Figure 8b showed a strong exothermic peak in DTA curve of CSHDS indicating oxidation reactions of cobalt and tin in addition to cyanate anions at 233 \({}^{\circ}\)C. In addition, the two endothermic peaks of water removal were also observed at 74 \({}^{\circ}\)C and 140 \({}^{\circ}\)C. The TGA and DTG curves in presence of oxygen showed similar diagrams to that in nitrogen gas, confirming the presence of two anions and intercalated water in the lattice of CSHDS. The thermal characteristics of the second sample, CSLDH-1 in nitrogen gas, were determined by DTA, DTG and TGA, as shown in Figure 9a. The total weight loss occurred through four steps, indicating removal of surface water, interlayered water, cyanate anions and nitrate anions, respectively [14; 15]. The DTG curve showed clear two peaks for the removal of the interlayered anions. Additionally, DTA revealed two endothermic peaks at 250.6 \({}^{\circ}\)C and 307.9 \({}^{\circ}\)C, confirming the presence of two interlayered anions, cyanate and nitrate, agreeing with the FTIR data. The different thermal processes of the sample CSLDH-1 are clearly distinguished when its thermal analyses are carried out in presence of air, as shown in Figure 9b. Figure 9b shows that TGA curve of CSLDH-1 has five weight losses with the different slopes indicating the removal of surface water, the removal of interlayered water, the oxidation of cyanate, the oxidation of nitrate and the dehydroxylation process. The DTG curve indicated the oxidation of both cyanate and nitrate anions through two peaks at 231 \({}^{\circ}\)C and 257 \({}^{\circ}\)C, respectively. Additionally, the oxidation reactions were confirmed by a strong exothermic peak at 236 \({}^{\circ}\)C in addition to weak peak at 270 \({}^{\circ}\)C.  
Figure 8: Thermal analyses of CSHDS in presence of: (a) nitrogen gas and (b) air. In the case of CSLDH-2, Figure 10a shows the thermal analyses in the presence of nitrogen gas. Three weight losses were observed in the TGA curve, indicating the existence of one kind of the interlayered anions agreeing with FTIR data. Figure 10a shows that 9 wt.% of surface water was lost at 99 \({}^{\circ}\)C and 6.2 wt.% of the interlayered water was removed at 231 \({}^{\circ}\)C [39]. In addition, 5.2 wt.% of nitrate anions were lost at 321 \({}^{\circ}\)C. DTG and DTA confirmed the presence of one kind of anions through one peak at 263 \({}^{\circ}\)C and 269 \({}^{\circ}\)C, respectively. In presence of air, these three weight losses were clearly observed in Figure 10b through TG and DTG diagrams.