Water-assisted crystallization of nanoporous tin oxide formed by anodic oxidation on cold sprayed tin coating

Highlights: • Crystallized tin oxide formed by dissolution-precipitation mechanism. • The rutile SnO₂ formed through reorganization of the SnO₆ octahedral units. • The texture of tin oxide film remains almost constant during annealing at 50 °C. • For other samples, the degree of preferred orientation decreases during annealing. -- Abstract: In this study, nanoporous tin oxide films were formed on cold sprayed tin coating via a modified electrochemical anodization process. The amorphous as-anodized was crystallized during a facile process with the assistance of hot water. The morphology and crystallinity of tin oxide films during thermal annealing and annealing by induced of hot water (50, 75, and 100 °C) during the various time were investigated by X-ray diffraction (XRD), field-emission scanning electron microscope (FESEM), and transmission electron microscope (TEM). It was observed that the crystallized tin oxide with the assistance of water was formed by the dissolution-precipitation mechanism. During this process, rutile SnO₂ was formed through reorganization of the SnO₆ octahedral units. Also, the texture coefficient and the degree of preferred orientation for different conditions were calculated from XRD spectra. It was found that the degree of preferred orientation of tin oxide film remains almost constant during annealing for the sample annealed by water with a temperature of 50 °C. However, for other samples, the degree of preferred orientation decreased during annealing.