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Synthesis, Structural and Optical Properties of L-Valine Modified ZnO Nanoparticles

R. P. Ganorkar, K. P. Kalkar and Y. S. Tamgadge

Zinc oxide (ZnO) nanoparticles (NPs) have been synthesized by co-precipitation method using various concentrations of L-valine as surface modifying agent. All these samples of ZnO NPs were calcined with slow heating rate at 6000 C for two hours for the removal of L-valine. UV-visible spectroscopy has been utilized to characterize calcined and uncalcined ZnO NPs. Fourier transform infrared spectroscopy confirmed the role of L-valine as surface modifier. Particles sizes of all uncalcined and calcined NPs have been calculated using Effective Mass Approximation method. ZnO NPs capped with L-valine before calcination exhibit very narrow particle size distribution (7 to 8 nm) whereas particle size increased (upto 18 nm) after removal of L-valine through the process of calcination. In both uncalcined and calcined ZnO NPs, particle size decreased for ZnO NPs synthesized using largest concentration of L-valine. X-ray diffraction analysis confirms the formation of pure phase wurtzite hexagonal ZnO NPs. Morphological studies have been performed using field emission scanning electron microscopy and transmission electron microscopy techniques.