Predictably, the characteristic band of wurtzite ZnO[2,14-16] in the range of 400-500 cm-1 is strongest in the case of single phase ZnO (sample F3) and weakest in the case of Zn5(OH)6(CO3)2 (sample F1). Other marked absorption bands in sample F3 correspond to O-H bending and stretching17,18. In the same range of vibrations by residual NO3- ions16, the carbonate stretches in samples F1 and F2 are observed at 1540 and 1480 cm-1 and similar to the previous report on sol-gel synthesis of hydrozincite19. The peaks at 1052 and 830 cm-1 are assigned to the ν1 and ν2 stretches of carbonate and are consistent with the carbonates being bound to an octahedral and tetrahedral zinc centre as expected in the hydrozincite structure20. In addition, the band centered at 2345 cm-1 is present exclusively in samples with Zn5(OH)6(CO3)2 (samples F1 and F2) and is attributed to the absorption of atmospheric CO2 on the metallic cation21. Interestingly, almost identical absorptions due to CO2 are found in hydrozincite in the literature19. ZnO can be prepared from either Zn5(OH)6(CO3)2[19,22] or Zn5(OH)8(NO3)2(H2O)2[6] by pyrolysis. However, the aim of this research is to sonochemically synthesize ZnO powders of controlled structure and morphology in a single step in order to reduce the cost of production when this is used in the industry. Therefore, the heat treatment was not attempted in this instance.