## 3 Results and Discussion
The heated stirring resulted in larger crystallites for both phases, inhibiting the sintering process and leading to larger specific surface areas. Adsorption-desorption curves obtained by the BET method are shown in Figure 7, where the hysteresis curves of the SCS products from a not-pretreated and a pretreated solution can be seen with 75 mL added into the initial mixture. The adsorption/desorption curves of the sample prepared without pretreatment of the initial SCS solution with 75 mL of added water are demonstrated in Figure 7a, and the pretreated one in Figure 7b. Both materials exhibited a distinct hysteresis loop, indicating that evaporation from pores and condensation in the pores are two completely different processes. This in turn implies that capillary condensation occurs within mesopores. The shape of the hysteresis loop of the pretreated sample was type A, according to the De Boer categorization, suggesting the existence of mainly cylindrical pores. Moreover, the bigger loop indicates better pore connection, thus there were many open pores. On the other hand, the type of loop in the not-pretreated sample corresponded to type C and its  
Figure 1:0 Hysteresis curves of the SCS materials prepared from (**a**) a not-pretreated and (**b**) a pretreated precursor solution. distinctly smaller hysteresis loop reflects the presence of many closed or semi-closed pores, such as wedge-shaped, cylindrical, and slit-shaped pores with one closed side or a dead end [21]. In addition, BET measurements provided the pore size distribution of the pretreated and not-pretreated samples in the case of 75 mL of water being added. Pore analysis measurements are exhibited in Figure 1:1 The results showed that there was no significant effect of the pretreatment on the final product's volume of nanopores or total porosity. The porosity, as well as the volume of the nanopores, were mainly influenced by the volume and velocity of the generated gases, considering that the composition of the precursor solution was identical. Thus, the similar resulting porosity was due to the same initial composition and identical behavior of the generated gases, as the reaction that took place was the same. In conclusion, the different values of the specific surface area can be attributed to the various crystallite sizes of the resulting phases, and not the materials' porosity characteristics. Thermal measurements concerning the reaction temperature as a function of the reaction time are presented in Figure 1:2  
Figure 1:3 BJH (Barrett, Joyner, and Halenda) adsorption cumulative pore volume concerning the influence of pretreatment on the basis of the initial mixture of 66.7% Ni(NO\({}_{3}\))\({}_{2}\), 33.3% glycine, and 75 mL H\({}_{2}\)O.  
Figure 1:4 _Cont._  
According to the obtained data, the pretreatment did not strongly influence the combustion temperature. The belated time of the combustion initiation for the not-pretreated sample was attributed to the quantity of the water that evaporated during the heated stirring. Nevertheless, the two observed peaks during SCS have different intensities and durations, implying a mechanism modification triggered only by the pretreatment application on the precursor solution. The first peak was attributed to the exothermic reaction of glycine with nickel nitrate, while the second to the reduction of nickel oxide with hydrogen and carbon. The resulting material of the pretreated solution had a more intensive and wider peak accorded to the nickel production, suggesting a higher concentration of nickel in the final product compared to the not-pretreated product. This was confirmed by the semi-quantitative analysis (refer to Figure 3), where the nickel concentration was indeed enhanced when pretreatment was applied. The well-developed dendrites in the pretreated sample resulted in the alteration of the combustion mechanism in comparison with the not-pretreated one. When the pretreatment was applied, the reaction between glycine and nickel nitrate was slower, while in the second case it was more violent.