Koteeswara Reddy Nandanapalli - Academia.edu (original) (raw)
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Papers by Koteeswara Reddy Nandanapalli
Materials Today Chemistry, 2021
Nano Energy, 2022
Wearable devices for remote medical systems require a reliable power supply to enable full operat... more Wearable devices for remote medical systems require a reliable power supply to enable full operation during long-term processes. Piezoelectric generators are promising energy sources that use human body movements to generate energy. The wearable device should be able to easily deform with tiny skin deformations to achieve continual energy generation from standard body movements. However, conventional piezoelectric devices cannot deform sufficiently in response to small movements, resulting in an extremely low energy-conversion efficiency when mounted on the human skin. In this study, we report on an
Applied Surface Science, 2011
Zn 1−x Gd x S (x = 0.00, 0.02 and 0.04) nanoparticles were synthesized by facile chemical co-prec... more Zn 1−x Gd x S (x = 0.00, 0.02 and 0.04) nanoparticles were synthesized by facile chemical co-precipitation method using PVP as a surfactant. ZnS nanoparticles could be doped with Gd ions during synthesis without altering the XRD patterns of ZnS. Also, the pattern of the powders showed cubic zincblende structure. The particle size obtained from the XRD studies lies in the range 3-5 nm, whereas from TEM analysis it is 4 nm for x = 0.02 sample. The UV-Vis absorption spectra revealed that Zn 1−x Gd x S nanoparticles exhibit strong confinement effect as the blue shift in the absorption spectra with that of the undoped ZnS. The photoluminescence spectra showed enhanced luminescence intensity and the entry of Gd into host lattice.
Materials Today Chemistry, 2022
Solar Energy Materials and Solar Cells, 2006
Journal of Industrial and Engineering Chemistry, 2008
ABSTRACT Highly crystalline rose-like microspheres made of nanosheets and hexagonal microdisks of... more ABSTRACT Highly crystalline rose-like microspheres made of nanosheets and hexagonal microdisks of zinc oxide (ZnO) were grown on Si and ZnO/Si substrates, respectively in solution at 90°C without the use of any surfactants. The microdisks had lower defects and better optical properties than the microspheres and showed a strong UV emission at 378nm. A possible growth mechanism based on the electrostatic forces between polarized ZnO nanostructures and substrates and the surface energy was proposed for the growth of microspheres and microdisks.
Chemical Engineering Journal
Journal of Alloys and Compounds
Critical Reviews in Solid State and Material Sciences
ABSTRACT
Scientific reports, Jan 24, 2015
One-dimensional ZnO nanowires (NWs) are a promising materials system for a variety of application... more One-dimensional ZnO nanowires (NWs) are a promising materials system for a variety of applications. Utilization of ZnO, however, requires a good understanding and control of material properties that are largely affected by intrinsic defects and contaminants. In this work we provide experimental evidence for unintentional incorporation of nitrogen in ZnO NWs grown by rapid thermal chemical vapor deposition, from electron paramagnetic resonance spectroscopy. The incorporated nitrogen atoms are concluded to mainly reside at oxygen sites (NO). The NO centers are suggested to be located in proximity to the NW surface, based on their reduced optical ionization energy as compared with that in bulk. This implies a lower defect formation energy at the NW surface as compared with its bulk value, consistent with theoretical predictions. The revealed facilitated incorporation of nitrogen in ZnO nanostructures may be advantageous for realizing p-type conducting ZnO via N doping. The awareness of...
Advanced Materials Research, 2012
Pure ZnO and Ag, Co doped ZnO nano particles [Zn1-xAgxCoyO, where x = 0.00 and 0.05, y = 0.05] we... more Pure ZnO and Ag, Co doped ZnO nano particles [Zn1-xAgxCoyO, where x = 0.00 and 0.05, y = 0.05] were synthesized by chemical co precipitation method without use of surfactant. All the prepared samples calcinated in 1 hour at 500oC, after that the morphology of the samples were evaluated by Scanning Electron Microscope (SEM). The X- ray diffraction (XRD) results indicated that the synthesized co-doped ZnO nano crystals had the pure hexagonal structure without any significant change in the structure affected by Ag and Co substitution. Dopant elements Ag and Co are present in the ZnO host material and conformed by Energy Dispersive Analysis of X-ray Spectra (EDAX). The incorporation of Ag+ in the place of Zn2+ has made a considerable decrease in the size of nano crystals as compared to pure ZnO nano particles (It is to be noted that Co should be kept constant at 5 mol %). Blue emission was observed by Photo Luminescence (PL) Spectra.
Solid-state electronics, 2005
Tin sulfide (Sn x S y ) films were prepared using spray pyrolysis technique at different substrat... more Tin sulfide (Sn x S y ) films were prepared using spray pyrolysis technique at different substrate temperatures (T s ), (100450 °C) on Corning 7059 glass substrates. The physical parameters such as electrical resistivity, Hall mobility and net carrier density of the films were ...
Applied Surface Science, 2007
ABSTRACT
Advances in Colloid and Interface Science
International Journal of Hydrogen Energy
ACS Applied Materials & Interfaces
Figure S1. Field-emission scanning electron micrographs of the PVA nanofibers: a) Low resolution ... more Figure S1. Field-emission scanning electron micrographs of the PVA nanofibers: a) Low resolution (scale bar = 15 µm). b) High resolution (scale bar = 2 µm).
Journal of Colloid and Interface Science
Materials Today Chemistry, 2021
Nano Energy, 2022
Wearable devices for remote medical systems require a reliable power supply to enable full operat... more Wearable devices for remote medical systems require a reliable power supply to enable full operation during long-term processes. Piezoelectric generators are promising energy sources that use human body movements to generate energy. The wearable device should be able to easily deform with tiny skin deformations to achieve continual energy generation from standard body movements. However, conventional piezoelectric devices cannot deform sufficiently in response to small movements, resulting in an extremely low energy-conversion efficiency when mounted on the human skin. In this study, we report on an
Applied Surface Science, 2011
Zn 1−x Gd x S (x = 0.00, 0.02 and 0.04) nanoparticles were synthesized by facile chemical co-prec... more Zn 1−x Gd x S (x = 0.00, 0.02 and 0.04) nanoparticles were synthesized by facile chemical co-precipitation method using PVP as a surfactant. ZnS nanoparticles could be doped with Gd ions during synthesis without altering the XRD patterns of ZnS. Also, the pattern of the powders showed cubic zincblende structure. The particle size obtained from the XRD studies lies in the range 3-5 nm, whereas from TEM analysis it is 4 nm for x = 0.02 sample. The UV-Vis absorption spectra revealed that Zn 1−x Gd x S nanoparticles exhibit strong confinement effect as the blue shift in the absorption spectra with that of the undoped ZnS. The photoluminescence spectra showed enhanced luminescence intensity and the entry of Gd into host lattice.
Materials Today Chemistry, 2022
Solar Energy Materials and Solar Cells, 2006
Journal of Industrial and Engineering Chemistry, 2008
ABSTRACT Highly crystalline rose-like microspheres made of nanosheets and hexagonal microdisks of... more ABSTRACT Highly crystalline rose-like microspheres made of nanosheets and hexagonal microdisks of zinc oxide (ZnO) were grown on Si and ZnO/Si substrates, respectively in solution at 90°C without the use of any surfactants. The microdisks had lower defects and better optical properties than the microspheres and showed a strong UV emission at 378nm. A possible growth mechanism based on the electrostatic forces between polarized ZnO nanostructures and substrates and the surface energy was proposed for the growth of microspheres and microdisks.
Chemical Engineering Journal
Journal of Alloys and Compounds
Critical Reviews in Solid State and Material Sciences
ABSTRACT
Scientific reports, Jan 24, 2015
One-dimensional ZnO nanowires (NWs) are a promising materials system for a variety of application... more One-dimensional ZnO nanowires (NWs) are a promising materials system for a variety of applications. Utilization of ZnO, however, requires a good understanding and control of material properties that are largely affected by intrinsic defects and contaminants. In this work we provide experimental evidence for unintentional incorporation of nitrogen in ZnO NWs grown by rapid thermal chemical vapor deposition, from electron paramagnetic resonance spectroscopy. The incorporated nitrogen atoms are concluded to mainly reside at oxygen sites (NO). The NO centers are suggested to be located in proximity to the NW surface, based on their reduced optical ionization energy as compared with that in bulk. This implies a lower defect formation energy at the NW surface as compared with its bulk value, consistent with theoretical predictions. The revealed facilitated incorporation of nitrogen in ZnO nanostructures may be advantageous for realizing p-type conducting ZnO via N doping. The awareness of...
Advanced Materials Research, 2012
Pure ZnO and Ag, Co doped ZnO nano particles [Zn1-xAgxCoyO, where x = 0.00 and 0.05, y = 0.05] we... more Pure ZnO and Ag, Co doped ZnO nano particles [Zn1-xAgxCoyO, where x = 0.00 and 0.05, y = 0.05] were synthesized by chemical co precipitation method without use of surfactant. All the prepared samples calcinated in 1 hour at 500oC, after that the morphology of the samples were evaluated by Scanning Electron Microscope (SEM). The X- ray diffraction (XRD) results indicated that the synthesized co-doped ZnO nano crystals had the pure hexagonal structure without any significant change in the structure affected by Ag and Co substitution. Dopant elements Ag and Co are present in the ZnO host material and conformed by Energy Dispersive Analysis of X-ray Spectra (EDAX). The incorporation of Ag+ in the place of Zn2+ has made a considerable decrease in the size of nano crystals as compared to pure ZnO nano particles (It is to be noted that Co should be kept constant at 5 mol %). Blue emission was observed by Photo Luminescence (PL) Spectra.
Solid-state electronics, 2005
Tin sulfide (Sn x S y ) films were prepared using spray pyrolysis technique at different substrat... more Tin sulfide (Sn x S y ) films were prepared using spray pyrolysis technique at different substrate temperatures (T s ), (100450 °C) on Corning 7059 glass substrates. The physical parameters such as electrical resistivity, Hall mobility and net carrier density of the films were ...
Applied Surface Science, 2007
ABSTRACT
Advances in Colloid and Interface Science
International Journal of Hydrogen Energy
ACS Applied Materials & Interfaces
Figure S1. Field-emission scanning electron micrographs of the PVA nanofibers: a) Low resolution ... more Figure S1. Field-emission scanning electron micrographs of the PVA nanofibers: a) Low resolution (scale bar = 15 µm). b) High resolution (scale bar = 2 µm).
Journal of Colloid and Interface Science