Combustion synthesis, characterization and Raman studies of ZnO nanopowders

Spherical shaped ZnO nanopowders (14–50 nm) were synthesized by a low temperature solution combustion method in a short time <5 min. Rietveld analysis show that ZnO has hexagonal wurtzite structure with lattice constants a = 3.2511(1) Å, c = 5.2076(2) Å, unit cell volume (V) = 47.66(5) (Å)3 and belongs to space group P63mc. SEM micrographs reveal that the particles are spherical in shape and the powders contained several voids and pores. TEM results also confirm spherical shape, with average particle size of 14–50 nm. The values are consistent with the grain sizes measured from Scherrer's method and Williamson–Hall (W–H) plots. A broad UV–vis absorption spectrum was observed at ∼375 nm which is a characteristic band for the wurtzite hexagonal pure ZnO. The optical energy band gap of 3.24 eV was observed for nanopowder which is slightly lower than that of the bulk ZnO (3.37 eV). The observed Raman peaks at 438 and 588 cm−1 were attributed to the E2 (high) and E1 (LO) modes respectively. The broad band at 564 cm−1 is due to disorder-activated Raman scattering for the A1 mode. These bands are associated with the first-order Raman active modes of the ZnO phase. The weak bands observed in the range 750–1000 cm−1 are due to small defects.

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► A ZnO nanopowder by LSC method with ODH as a fuel is reported for the first time.
► PXRD, SEM, TEM, FTIR, UV–Vis, Raman, PL, TL and EPR studies were carried out.
► We report for first time TL properties of ZnO nanopowders irradiated by γ-rays.
► Trapping parameters with various γ- doses are calculated using peak shape method.