Electrospun tin oxide nanofibers

Abstract

Ultrafine tin oxide (SnO₂) fibers in the rutile structure, with diameters ranging from 60nm to several microns, were synthesized using electrospinning and metallorganic decomposition techniques. In this work we use a precursor solution which is a mixture of a pure SnO₂ sol made from SnCl₄ : H₂O : C₃H₇OH : 2-C₃H₇OH at a molar ratio of 1:9:9:6, and a viscous solution made from poly(ethylene oxide) (PEO) (molecular weight 900,000) and chloroform CHCl₃ at a ratio of 200mg PEO/10mL CHCl₃. This solution allows obtaining an appropriate viscosity for the electrospinning process. The as deposited fibers were sintered at 400, 500, 600, 700 and 800°C in air for two hours. Previous results using this method and characterizing the fibers with scanning electron microscopy (SEM), x-ray diffraction (XRD), Raman microspectrometry and x-ray photoelectron spectroscopy (XPS) showed that up to the sintering temperature of 700°C, the synthesized fibers are composed of SnO₂. Further analysis using SEM, Profilometry, Atomic Force Microscopy (SPM), Auger Spectroscopy and I/V analysis is presented in this paper. The results show that the fibers are composed of tin oxide and that smooth and continuous fibers in different shapes (straight, curved, ribbon-like, and spring-like) can be obtained using this method. The change in resistivity as a function of the annealing temperature can be attributed to the thermally activated formation of a nearly stoichoimetric solid.