Journal of Materials Science-materials in Electronics
Large scale flower-like ZnO microstructures were synthesized by microwave assisted hydrothermal m... more Large scale flower-like ZnO microstructures were synthesized by microwave assisted hydrothermal method in short reaction time. These flower-like structures were composed of dozen of rods like building block units radiated from a centre. Similar morphology was not obtained in normal hydrothermal method. TEM microscopy study showed that individual rods of flower-like structures are single crystalline in nature and preferentially grown along [0001] direction. Growth mechanism showed that microwave induction and ethylenediamine (EDA) played an important role in the formation of flower-like ZnO microstructures. Photoluminescence property of flower-like ZnO microstructures showed deep level emission along with UV emission which indicates the presence of structural defects. The nature of defect responsible for deep level emission was examined by annealing the sample in different atmospheres. There was no significant effect of annealing the sample in air and argon atmospheres however in hydrogen atmosphere deep level emissions were passivated.
Journal of Materials Science-materials in Electronics, 2011
A facile and environment-friendly ultrasonic route, to synthesize well-defined nearly spherical s... more A facile and environment-friendly ultrasonic route, to synthesize well-defined nearly spherical shape ZnO nanoparticles and spindle shape ZnO microrods, has been reported. The phase and structural analysis carried out by X-ray diffraction, confirmed the formation of hexagonal wurtzite structure of ZnO. Morphological studies carried out by electron microscope techniques, showed the formation of spherical shape ZnO nanoparticles in the absence of surfactant while spindle shape ZnO microrods in the presence of surfactant, under similar experimental conditions. Transmission electron microscope study showed that as prepared ZnO structures were single crystalline in nature and preferentially grew along [0001] direction. Furthermore, the optical property investigated by photoluminescence spectroscopy, showed only UV emission in case of ZnO nanoparticles where as UV as well as deep level emission in ZnO microrods. The origin of deep level emission in ZnO microrods was related to the structural defects of ZnO microcrystal.
Journal of Materials Science-materials in Electronics, 2010
A simple CTAB-assisted hydrothermal synthesis of undoped and copper-doped ZnO nanorods is reporte... more A simple CTAB-assisted hydrothermal synthesis of undoped and copper-doped ZnO nanorods is reported. The phase and structural analysis carried out by X-ray diffraction, shows the formation of hexagonal wurtzite structure of ZnO. Morphology of the ZnO nanorods was investigated by electron microscopy techniques which showed the formation of well dispersed regular shape ZnO nanorods of 100 ± 10 nm in diameter and 900 ± 100 nm in length. However, size of the copper doped ZnO nanorod slightly increased with increasing copper concentration. Furthermore, the selected area electron diffraction pattern and high resolution transmission electron microscopy reveal that both the undoped and copper doped ZnO nanorods were single crystalline in nature and preferentially grew up along [0001] direction. Optical property was investigated by photoluminescence spectroscopy. The effects of copper doping on the photoluminescence property of ZnO nanorods were investigated.
Journal of Materials Science-materials in Electronics, 2009
ZnO nanorods were grown by cetyl trimethylammonium bromide assisted hydrothermal technique from a... more ZnO nanorods were grown by cetyl trimethylammonium bromide assisted hydrothermal technique from a single molecular precursor. The phase and structural analysis were carried out by X-ray diffraction technique and Raman spectroscopy, respectively. The phase and structural analysis has suggested that as prepared nanorods have hexagonal wurzite structure. Morphology of the nanorods was investigated by electron microscopy techniques which showed the formation of well dispersed nanorods of 100 ± 10 nm in diameter and 900 ± 100 nm in length. Optical properties were investigated by photoluminescence spectroscopy. As prepared ZnO nanorods have shown intense room temperature photoluminescence peak in the violet region at 403 nm. Absence of defect mediated green luminescence peak suggests the formation of well crystalline ZnO nanorods without any impurities or structural defects.
Journal of Materials Science-materials in Electronics
Large scale flower-like ZnO microstructures were synthesized by microwave assisted hydrothermal m... more Large scale flower-like ZnO microstructures were synthesized by microwave assisted hydrothermal method in short reaction time. These flower-like structures were composed of dozen of rods like building block units radiated from a centre. Similar morphology was not obtained in normal hydrothermal method. TEM microscopy study showed that individual rods of flower-like structures are single crystalline in nature and preferentially grown along [0001] direction. Growth mechanism showed that microwave induction and ethylenediamine (EDA) played an important role in the formation of flower-like ZnO microstructures. Photoluminescence property of flower-like ZnO microstructures showed deep level emission along with UV emission which indicates the presence of structural defects. The nature of defect responsible for deep level emission was examined by annealing the sample in different atmospheres. There was no significant effect of annealing the sample in air and argon atmospheres however in hydrogen atmosphere deep level emissions were passivated.
Journal of Materials Science-materials in Electronics, 2011
A facile and environment-friendly ultrasonic route, to synthesize well-defined nearly spherical s... more A facile and environment-friendly ultrasonic route, to synthesize well-defined nearly spherical shape ZnO nanoparticles and spindle shape ZnO microrods, has been reported. The phase and structural analysis carried out by X-ray diffraction, confirmed the formation of hexagonal wurtzite structure of ZnO. Morphological studies carried out by electron microscope techniques, showed the formation of spherical shape ZnO nanoparticles in the absence of surfactant while spindle shape ZnO microrods in the presence of surfactant, under similar experimental conditions. Transmission electron microscope study showed that as prepared ZnO structures were single crystalline in nature and preferentially grew along [0001] direction. Furthermore, the optical property investigated by photoluminescence spectroscopy, showed only UV emission in case of ZnO nanoparticles where as UV as well as deep level emission in ZnO microrods. The origin of deep level emission in ZnO microrods was related to the structural defects of ZnO microcrystal.
Journal of Materials Science-materials in Electronics, 2010
A simple CTAB-assisted hydrothermal synthesis of undoped and copper-doped ZnO nanorods is reporte... more A simple CTAB-assisted hydrothermal synthesis of undoped and copper-doped ZnO nanorods is reported. The phase and structural analysis carried out by X-ray diffraction, shows the formation of hexagonal wurtzite structure of ZnO. Morphology of the ZnO nanorods was investigated by electron microscopy techniques which showed the formation of well dispersed regular shape ZnO nanorods of 100 ± 10 nm in diameter and 900 ± 100 nm in length. However, size of the copper doped ZnO nanorod slightly increased with increasing copper concentration. Furthermore, the selected area electron diffraction pattern and high resolution transmission electron microscopy reveal that both the undoped and copper doped ZnO nanorods were single crystalline in nature and preferentially grew up along [0001] direction. Optical property was investigated by photoluminescence spectroscopy. The effects of copper doping on the photoluminescence property of ZnO nanorods were investigated.
Journal of Materials Science-materials in Electronics, 2009
ZnO nanorods were grown by cetyl trimethylammonium bromide assisted hydrothermal technique from a... more ZnO nanorods were grown by cetyl trimethylammonium bromide assisted hydrothermal technique from a single molecular precursor. The phase and structural analysis were carried out by X-ray diffraction technique and Raman spectroscopy, respectively. The phase and structural analysis has suggested that as prepared nanorods have hexagonal wurzite structure. Morphology of the nanorods was investigated by electron microscopy techniques which showed the formation of well dispersed nanorods of 100 ± 10 nm in diameter and 900 ± 100 nm in length. Optical properties were investigated by photoluminescence spectroscopy. As prepared ZnO nanorods have shown intense room temperature photoluminescence peak in the violet region at 403 nm. Absence of defect mediated green luminescence peak suggests the formation of well crystalline ZnO nanorods without any impurities or structural defects.
Uploads
Papers by Prabhakar Rai