Structural, EPR, photo and thermoluminescence properties of ZnO:Fe nanoparticles

Zn(1−x)Fe(x)O(1+0.5x) (x = 0.5–5 mol%) nanoparticles were synthesized by a low temperature solution combustion route. The structural characterization of these nanoparticles by PXRD, SEM and TEM confirmed the phase purity of the samples and indicated a reduction in the particle size with increase in Fe content. A small increase in micro strain in the Fe doped nanocrystals is observed from W–H plots. EPR spectrum exhibits an intense resonance signal with effective g values at g ≈ 2.0 with a sextet hyperfine structure (hfs) besides a weak signal at g ≈ 4.13. The signal at g ≈ 2.0 with a sextet hyperfine structure might be due to manganese impurity where as the resonance signal at g ≈ 4.13 is due to iron. The optical band gap Eg was found to decrease with increase of Fe content. Raman spectra exhibit two non-polar optical phonon (E2) modes at low and high frequencies at 100 and 435 cm−1 in Fe doped samples. These modes broaden and disappear with increase of Fe dopant concentration. TL measurements of γ-irradiated (1–5 kGy) samples show a main glow peak at 368 °C at a warming rate of 6.7 °Cs−1. The thermal activation parameters were estimated from Glow peak shape method. The average activation energy was found to be in the range 0.34–2.81 eV.