Effects of Li doping on structural, electronic, optical and magnetic properties of Fe 0.04 Zn 0.96 O nanocrystalline samples

Abstract

Abstract Sol-gel synthesized nanocrystalline samples of Li x Fe 0.04 Zn 0.96−x O (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 ZnFe 2 O 4 . As determined from the Rietveld analysis, the presence of ZnFe 2 O 4 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 Fe 3+ state. From the UV–visible spectroscopy, the energy band gap (E g ) of pure ZnO has been estimated to be 3.064 eV, whereas on Fe doping E g has increased. No significant change in E g due to Li doping has been observed. Magnetization measurements have revealed that the samples containing ZnFe 2 O 4 (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 ZnFe 2 O 4 .