Fig. 7. SEM images of TiO₂ nanofibers prepared from the precursors with (a and b) ×0.5, (c and d) ×1.5, and (e and f) ×2.5 TiO₂/polymer yield mass ratios after (a, c and e) calcination at 750 °C and (b, d and f) sintering at 1000 °C. Corresponding higher magnification images are shown in insets.