ZnO nanoflowers were synthesized by the hydrothermal process at an optimized growth
temperature of 200 ◦C and a growth/reaction time of 3 h. As-prepared ZnO nanoflowers were
characterized by x-ray diffraction, scanning electron microscopy, UV–visible and Raman
spectroscopy. X-ray diffraction and Raman studies reveal that the as-synthesized flower-like
ZnO nanostructures are highly crystalline with a hexagonal wurtzite phase preferentially
oriented along the (1 0 1 1) plane. The average length (234–347 nm) and diameter (77–106 nm)
of the nanorods constituting the flower-like structure are estimated using scanning electron
microscopy studies. The band gap of ZnO nanoflowers is estimated as 3.23 eV, the lowering of
band gap is attributed to the flower-like surface morphology and microstructure of ZnO. Room
temperature photoluminescence spectrum shows a strong UV emission peak at 392 nm, with a
suppressed visible emission related to the defect states, indicating the defect free formation of
ZnO nanoflowers that can be potentially used for UV light-emitting devices. The suppressed
Raman bands at 541 and 583 cm−1 related to defect states in ZnO confirms that the ZnO
nanoflowers here obtained have a reduced presence of defectsCochin University of Science and TechnologyJ. Phys. D: Appl. Phys. 45 (2012) 425103 (6pp
