EFFECT OF SYNTHESIS CONDITIONS ON THE CRYSTAL STRUCTURE AND MORPHOLOGY OF TIN PHOSPHIDE/PHOSPHATE-BASED CARBON COMPOSITE NANOFIBERS

In this study, the structural and morphological changes of carbon composite nanofibers based on tin phosphide/phosphate were investigated depending on the synthesis conditions. The composites were obtained through electrospinning and two-step thermal treatment, comprised of pre-oxidation and carbonization, from a mixture of polyvinylpyrrolidone (PVP), tin chloride dihydrate (SnCl₂⋅2H₂O), and phosphoric acid in ethanol: H₂O solution. The physical-chemical properties of the resultant nanofibers were studied by X-Ray diffraction, scanning electron microscopy (SEM), and CHNS elemental analyzer. The mass ratio of SnCl₂⋅2H₂O:PVP, the pre-oxidation temperature, and the annealing time determined the phase composition and morphology of the nanofibers. Samples annealed at 900°C for 10 min exhibited high crystallinity, the formation of the SnP phase, and phosphorus evaporation, which contributed to the development of a gradient structure. SEM results showed that the fiber diameter depended on the mass fraction of SnCl₂⋅2H₂O. An increase in the pre-oxidation temperature led to carbon oxidation and the formation of an amorphous structure. Thus, by adjusting the annealing conditions, the structural properties of carbon composite nanofibers can be controlled. These materials have the potential to serve as promising anode materials for high-performance energy storage systems.

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