Rajni Verma; Bhanu Mantri; Avanish Kumar Srivastava
Abstract
In the present study, ZnO and TiO2 nanostructures of different size have been synthesized in high yield with excellent repeatability by simple, economical and environmentally benign chemical route. ZnO quantum dots and nanorods of tuned aspect ratio were evolved by optimising the reaction conditions ...
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In the present study, ZnO and TiO2 nanostructures of different size have been synthesized in high yield with excellent repeatability by simple, economical and environmentally benign chemical route. ZnO quantum dots and nanorods of tuned aspect ratio were evolved by optimising the reaction conditions such as by varying solvent composition, precursor concentration and by using different additives. On the other hand, the synthesis of brookite, the rare phase, anatase and rutile, the stable phases of TiO2 were also achieved by just varying the annealing temperature from 400 to 615 °C. The obtained nanostructures were rationalized by various characterization techniques such as XRD, FTIR, Raman, SEM, HR- TEM, UV-Vis and PL. The Phase formation and structure determination were identified by using XRD, FTIR and Raman Spectra, SEM and HR-TEM were performed to determine the morphology and particle size. The aspect ratio was calculated to be in the range of 3.2-9.4 in case of ZnO NRs, and particle size was found to be 2-5 nm for ZnO QDs of wurtzite phase and ~ 10 nm for TiO2 (anatase phase) NPs, respectively. The UV-Vis optical absorption spectrum demonstrates the band gap value of 3.60, 4.02 and 3.40 eV for ZnO NRs, QDs and TiO2 NPs respectively. The UV-Vis optical absorption spectrum demonstrates the band gap and room temperature PL spectra illustrates about the various defects present in the sample. Various chemical reactions and mechanism involved in producing these nanostructures are dealt in detail. The future prospective of these metal oxide nanostructures lie in photocatalysis, sensors and biomedical applications.
Jitendra Gangwar; Kajal Kumar Dey; Surya Kant Tripathi; Avanish Kumar Srivastava
Abstract
We report the synthesis of nano-scaled alumina of varied dimensions through a novel optimized processing of aluminum nitrate. The X-ray diffractometry confirmed the formation of X- and γ- phases of alumina particles in the nano region, depending on the annealing conditions during processing. Subsequently, ...
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We report the synthesis of nano-scaled alumina of varied dimensions through a novel optimized processing of aluminum nitrate. The X-ray diffractometry confirmed the formation of X- and γ- phases of alumina particles in the nano region, depending on the annealing conditions during processing. Subsequently, a detailed microscopic investigation revealed the morphological alterations and crystallographic information even at lattice scale. The presence of different bonds and band energies were investigated by employing infra-red and photoluminescence spectrometry, respectively. The evolution of fascinating microstructure, phase formations and optical bands has been presented and discussed to elucidate the systematic evolution of different crystalline phases (α and γ) from an amorphous alumina with increased annealing temperature.
