The FTIR spectra of the three nanopowders are shown in Fig. 4. The FTIR spectrum of the ZnO nanopowder shown
in Fig. 4a shows only one significant peak at around
429 cm-1 that can be ascribed to the characteristic อibrational
mode of Zn–O bond. The peaks at around 446 and
540 cm-1 in Fig. 4b can be ascribed to the characteristic
vibrations of the Fe–O bond. The FTIR spectrum of
ZnFe2O4/ZnO nanopowder is shown in Fig. 4c. The peak
due to Zn–O bond was shifted to around 352 cm-1 whereas
the peaks due to Fe–O bond were shifted to around 416 and
542 cm-1. The shift in the peaks of Zn–O peak and the Fe–
O may be attributed to the change in particle size and hence
the metal ion-oxygen bond distances (Thomas and George
2009; Ladgaonkar et al. 2002). The peaks at around
3400–3500 cm-1 in the FTIR spectra can be ascribed to the
–OH group of water adsorbed on the surface of the nanopowders
(Sumetha 2008; Darezereshki 2011).