Structural and morphological studies of ZnO nanostructures

Abstract

Zinc oxide (ZnO) nanostructures were manufactured successfully using the sol-gel approach in this study. The impact of calcination temperatures on their structural and morphological properties is studied using three different calcination temperatures (350, 400, and 450 °C). XRD, FE-SEM, EDS, and a Raman scattering spectroscope were used to characterize the samples. In all samples, X-ray diffraction (XRD) of calcined samples (350-450 °C) reveals the presence of the wurtzite hexagonal nanocrystalline structure of ZnO compound. The XRD patterns showed no additional peaks, indicating that the final product is exclusively ZnO nanostructures. The FE-SEM pictures of a calcined ZnO sample at 450°C revealed a porous structure, longer length and diameter, and agglomeration of mixed polyhedral shape particles as the calcination temperature increased. The presence of necessary oxide material in the EDS spectrum confirmed the synthesis of ZnO, indicating that the purity of ZnO was appropriate. Finally, using Raman spectroscopy, the vibrational characteristics of ZnO were studied. Several bands in Raman spectra appeared to belong to ZnO vibrational modes, confirming the purity of the produced ZnO samples. The findings of such a study were presented in this paper.

Temperature Dependence on Structural Properties of Liquid Phase Synthesized ZnO

“…This implies that a slight variation in the lattice parameters occurs as growth temperature increases, attributable to a change in the stress in the ZnO nanoparticles. This type of result in the shift of peak position angle to higher values has also been reported by [14], [15]. This is shown in Figures 4 (a The lattice parameters, a and c were plotted against the temperatures as shown in figure 5.…”

“…It can be said that, generally, as the temperature is increased, the lattice parameters, a, and c decreased. The trend of the decrease in the value of the lattice parameters is supported by [14], [38] [39]. The values of the lattice parameter were found to be close to those of the standard ZnO from the ISCD cards 01-073-8765 and 01-078-2585 (3.2533 -3.2522 and 5.2072 -5.2095).…”

“…From the XRD it can be seen that the ZnO 2 decomposed into ZnO, and crystallinity improved as the temperature was increased. Additionally, the distinctive peaks got higher and sharper, indicating an enhancement of crystallinity nature due to agglomeration [14]. Peak indexing shows that samples prepared at 140°C and 160°C produced planes at (100), ( 002), ( 101), (102), (110), ( 103) and (112) at peak positions (2θ values) of approximately 31.76º, 34.31º, 36.22º, 47.52º, 56.63º, 62.83º and 67.92º which were found to be ZnO and confirms the hexagonal wurtzite structure accordingly.…”

“…where d is the lattice plane spacing and h, k, l are the Miller indices. The positional or internal parameter, u which is a measure of the amount by which each atom is displaced with respect to the next along the 'c' axis is determined by equation 2 [7], [14], [16], [17]:…”

“…where D is the particle size in nm, k is a constant of value 0.9, λ is the X-ray wavelength in nm, θ is the Bragg's angle in radians, and β is the full width at half maximum of the peak in radians [12], [17], [23]. The dislocation density (δ), which is the number of defects in the sample is calculated using equation 8 [7], [8], [14], [24];…”