| Abstract
| - Tin oxide intercalated montmorillonite nanocomposites were prepared by an in situ preadsorption methodin aqueous solution in the absence of surfactants and organic solvents. The tin oxide particle size wascontrolled by adjusting the relative supersaturation ratio, S (S = (Q − L)/L), where Q is the amount ofthe dissolved material, the Sn(OH)4 precipitate, and L is its solubility). Increasing the relative supersaturationresults in a progressive increase of the size of the SnO2 nanoparticles up to a maximum, after which afurther increase of S results in a decrease of the size of the nanoparticles, since their growth is inhibited.Calcination of the 2−3 nm diameter SnO2/Sn(OH)4 nanoparticles at 400 °C for 3 h resulted in the formationof an oxide lattice structure from a tin oxide/hydroxide structure. XRD measurements indicated the sizesof tin oxide nanocrystals to be in the 1−2 nm diameter range between the layers of montmorillonite. Thespecific surface area of montmorillonite significantly changed from 30 to 112.5 m2/g upon SnO2 intercalation,as evidenced by BET. The thermoanalytical investigations revealed the optimal calcination temperatureof the nanocomposites (400 °C) and proved the presence of the SnO2 nanoparticles by the heat effect oftheir crystallization process. The Mössbauer studies of the samples indicated the particle size dependenceon the effective vibrating mass (Meff) and the Debye temperature (ϑM) of the tin oxide nanocrystals. It wasconfirmed by all of the measurement methods that smaller particle size can be attained by increasing therelative supersaturation ratio of the Sn(OH)4 precipitate.
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