Figure 5.

aUV–vis absorbance spectra of rice-like HfO2nanostructures obtained by MH at 140 °C for 1 h. Inset illustrates a wide band model composed of intermediary levels within the band gap as well as the indirect electronic transition process.bPL spectrum at room temperature of rice-like HfO2nanostructures. Inset shows the different bond angles between the O–H–O bonds for the [HfO6] clusters

Eliziário et al. Nanoscale Research Letters 2009 4:1371-1379   doi:10.1007/s11671-009-9407-6