# Mechanical Activation of Smectine-Based Nanocomposites for Creation of Smart Fertilizers
## 3 Results  
### Physical and Chemical Characteristics of Composites  
The XRD patterns for the composites (Figure 1) show the prominent reflections of smectite (montmorillonite) at 14.3-17.3 and 4.5 A. The reflections at 4.0, 3.6, 3.1, 2.8, 2.5, 2.4, 2.2, 1.8, and 1.7 A confirm the presence of nitrogen. The reflections at 4.3 and 3.4 A correspond to quartz (4%) impurities in the smectite concentrate. The XRD patternsalso demonstrate the presence of illite and kaolinite (both up to 0.5%) at 10.0 and 7.1 A, respectively. The basal reflection of smectite shifts from 14.3 to 17.3 A (Figure 1) as the grinding time is increased from 3 min to 11 min. The composite includes relics of smectite particles and flakes (Figure 2). A nitrogen coating mantles mineral micro-aggregates in S3N2 pm11. The length of the mineral micro-aggregate's ranges from 10 to 200 \(\upmu\)m. The urea coating may be up to 5 \(\upmu\)m thick (Figure 2C). The urea coating thickens gradually as the operation time increases. The adsorbed urea crystallites within the coating have diameters ranging from 30 to 80 nm. They are admixed with nanoparticles of smectite (Figure 3). TEM images with SAED (Figure 3) show distinctive interplanar spacings for the following minerals: smectite of 17.1 A and 4.5 A; and urea of 3.6 A, 3.1 A, and 2.8 A.  
Figure 3: Transmission electron microscopy (TEM) images with selected area electron diffraction (SAED) patterns showing smectite (Sme) and urea (U) crystallite for S3N2 pm11 composite. Figure 2: SEM images of composites S3N2 pm3 (**A**), S3N2 pm8 (**B**), and S3N2 pm11 (**C**). Note the thicker urea coating in S3N2 pm11 compared to other composites. U—urea particles, Sme—smectite (montmorillonite) relics. The composites of S3N2 pm3/8/11 (Figure 4) show minor changes of low wavenumber with increasing activation time. FTIR spectra of composites include peaks of CO at 790 cm\({}^{-1}\) and Si-O stretching at 1050 cm\({}^{-1}\). All composites show a gentle peak at 720 cm\({}^{-1}\) (NH\({}_{2}\)). The NH\({}_{2}\) peak is identified at 1155 cm\({}^{-1}\) in all the composites. Composites exhibit the asymmetric deformation of the C-N at 1463 cm\({}^{-1}\). Peaks at 1629-1650 cm\({}^{-1}\) (NH\({}_{2}\)) and the flat 1662-1683 cm\({}^{-1}\) (NH) are distinctive of the composites. These two peaks appear stronger in S3N2 pm11 compared to S3N2 pm 3/8. FTIR peaks of S3N2 pm11 characteristically exhibit a peak at 3344 cm\({}^{-1}\), probably reflecting the nitrogen coating. The NH\({}_{2}\) peak shifts from 3485 to 3440 cm\({}^{-1}\) with increasing grinding time. All composites show a peak of 3620 cm\({}^{-1}\), which is associated with IR-vibration Al-OH-Al of montmorillonite. The composites are characterized by six weight loss steps on the thermogravimetric (TG) curves: 0-135 \({}^{\circ}\)C, 135-240 \({}^{\circ}\)C, 240-300 \({}^{\circ}\)C, 300-450 \({}^{\circ}\)C, 450-580 \({}^{\circ}\)C, and 580-1000 \({}^{\circ}\)C (Figure 5, Table 1). The curves of composites exhibit weight losses by 0.8-1.1% and 20.4-21.0% in the steps of 20-135 \({}^{\circ}\)C and 135-240 \({}^{\circ}\)C, because of the release of free water and adsorbed urea, respectively [49; 50]. The third and fourth weight loss steps at 240-300 \({}^{\circ}\)C and 300-450 \({}^{\circ}\)C indicate the decomposition of absorbed and intercalated urea, respectively [39; 51]. The absorbed urea (within smectite micro-aggregates) is removed by weight losses of 3.2-3.7% (equal to 8-9.2% of used urea) in a weight loss range of 240-300 \({}^{\circ}\)C. Part of the intercalated urea is lost by 12.9-13.6% in a step of 300-450 \({}^{\circ}\)C. The fifth step at the temperature range of 450-590 \({}^{\circ}\)C corresponds to the removal of intercalated urea [52] by 4.1-4.9% from the composites. In general, the intercalated urea in composites becomes 17.0-18.4%, equal to 42.5-46.0% of used urea. The temperature interval 590-1000 \({}^{\circ}\)C (the six weight loss step) corresponds to the dehydroxylation of mineral [53] by 2.0-3.1%.