Self-organized double-wall oxide nanotube layers on glass-forming Ti-Zr-Si(-Nb) alloys

In this work, we report for the first time on the use of melt spun glass-forming alloys - Ti₇₅Zr₁₀Si₁₅ (TZS) and Ti₆₀Zr₁₀Si₁₅Nb₁₅ (TZSN) - as substrates for the growth of anodic oxide nanotube layers. Upon their anodization in ethylene glycol based electrolytes, highly ordered nanotube layers were achieved. In comparison to TiO₂ nanotube layers grown on Ti foils, under the same conditions for reference, smaller diameter nanotubes (~116nm for TZS and ~90nm for TZSN) and shorter nanotubes (~11.5μm and ~6.5μm for TZS and TZSN, respectively) were obtained for both amorphous alloys. Furthermore, TEM and STEM studies, coupled with EDX analysis, revealed a double-wall structure of the as-grown amorphous oxide nanotubes with Ti species being enriched in the inner wall, and Si species in the outer wall, whereby Zr and Nb species were homogeneously distributed.