Green synthesis of zinc oxide nanostructure using Azadirachta Indica leaf extract and its structural and microstructural study

Abstract

A green synthesis method using Azadirachta Indica leaf extract has been used to synthesized ZnO nanostructures. TEM image confirmed the formation of nanoparticles of size in the range of ∼50–100 nm. The stochiometry was also confirmed from the EDX spectroscopy. The structural analysis of the synthesized material was performed using the x-ray diffraction (XRD) data. The ZnO nanocrystals exhibit wurtzite unit cell structure as revealed from the XRD pattern. The calculation of lattice parameters shows that the distortion in the structure is very small. The material is highly crystalline with crystallite size of 20.05 nm and microstrain of 5.926 × 10−4. In this context crystallinity index is also calculated. The growth of the crystal is anisotropic as observed from the intensity of the diffraction and was quantified through the parameter degree of orientation. The synthesized ZnO nanostructure has large specific surface area. Other crystal parameters like Zn–O bond length, u-parameter, crystal volume were also calculated form the XRD pattern and show the structural perfection of the grown nanocrystal with a good figure of merit. Raman-shift measurements showed the existence of various phonon vibrational modes of the ZnO lattice. The material being synthesized by green approach is non-toxic in nature and may have potential applications in nanomaterials based medicinal and therapeutic applications.

Peak Profile Analysis of X-ray Diffraction Pattern of Zinc Oxide Nanostructure

“…The higher the growth rate, the smaller the surface area of the plane, and hence the lower the intensity [21]. This growth anisotropy is characterized by a parameter known as the degree of orientation defined by [22] hkl hkl hkl…”

“…This is due to the variation in growth conditions leading to a higher multiplicity factor for the (002) plane. The interplaner spacings (dhkl) for different observed (hkl) planes were calculated from the Bragg's equation [22] 2 sin .…”

“…A small difference was observed due to the existence of strain in crystals. The crystallite size and strain were calculated using Scherrer's formula [19][20][21][22] 0.89 ,. Here,  is the wavelength of X-ray used, βhkl is the full width at half maximum (FWHM) corresponding to the glancing angle θ, and K is a constant with a value of 0.89.…”

“…The dislocation density (Δ), representing dislocation line lengths per unit volume in the crystal, was calculated from the crystallite size using the relation [22]…”

“…Specific surface area is an important parameter representing the available surface area per unit mass of the material. It is defined as [22] 7 2…”