CommunicationEffects of Li doping on structural, electronic, optical and magnetic properties of Fe0.04Zn0.96O nanocrystalline samples

- Fe and Li doped/co-doped ZnO samples have been prepared by sol-gel technique.
- Effects of Li doping in Fe doped ZnO have been investigated.
- Fe doping increases energy band gap of ZnO due to Burstein-Moss effect.
- Observed strong ferromagnetism is attributed to ZnFe2O4 impurity phase.

Sol-gel synthesized nanocrystalline samples of LixFe0.04Zn0.96−xO (x = 0.0, 0.02, 0.04 and 0.06) have been investigated through X-ray diffraction (XRD), X-ray absorption near edge spectroscopy (XANES), UV-visible absorption spectroscopy and magnetic measurements. First three samples, i.e., x = 0.0, 0.02 and 0.04, have been found to possess an impurity phase of ZnFe2O4. As determined from the Rietveld analysis, the presence of ZnFe2O4 phase has decreased on Li doping and for x = 0.06, it is negligibly small. XANES analysis shows that the majority of Fe ions is in Fe3+ state. From the UV-visible spectroscopy, the energy band gap (Eg) of pure ZnO has been estimated to be 3.064 eV, whereas on Fe doping Eg has increased. No significant change in Eg due to Li doping has been observed. Magnetization measurements have revealed that the samples containing ZnFe2O4 (x = 0.0, 0.02 and 0.04) phase exhibit strong ferromagnetic spin-glass behaviour at low temperature and a weak ferromagnetic ordering at the room temperature. However, the sample with x = 0.06 does not show any significant ferromagnetic ordering in the temperature range of 2-300 K. The observed magnetic ordering and spin-glass behaviour in first three samples have been attributed to the impurity phase of ZnFe2O4.