Figure 5.

a Weight change and heat flow recorded for Na₇(H₃O)Nb₆O₁₉·14H₂O nanobelts. b XRD pattern of NaNbO₃ nanobelts (a) and the standard pattern of bulk NaNbO₃ (b). c UV–Vis spectra of (a) Na₇(H₃O)Nb₆O₁₉·14H₂O nanobelts, (b) NaNbO₃ nanobelts, and (c) bulk NaNbO₃. d Room temperature PL spectra of NaNbO₃ nanobelts, the inset shows an enlarged spectrum.