Figure 1 shows the morphology and the crystalline peaks of the hydrothermal synthesized ZnO nanoparticles. The ZnO was observed as the clusters of nanoparticles, showing the crystalline peaks at 2θ=31.8°, 34.5°, 36.4°, 47.7° and 56.8°.These crystalline peaks were corresponded to hexagonalstructure as referenced in JCPDS No.36–1451. In addition, the board crystalline peaks were obtained, indicating the formation of nanocrystallite size of ZnO. XRD peak broadening was used to determine the size of the primary crystallite using the Scherrer equation (Eq. 1) is 25.4 nm.
Where K is equal to 0.9, λ is the X-ray wavelength (λ=1.54Å), β is the full half width maximum of the (101) diffraction peak, and θ is Bragg diffraction angle.