3.1.1. XRD Analysis

The XRD pattern of Fe3O4 nanoparticles formed by solvothermal method is shown in Figure 2. The XRD pattern of formed nanoparticles resembles with JCPDS card No# 019–0629 for magnetite, with no extraneous peak, which indicates the high purity of the magnetite. The 2-theta value of peaks were 29.95◦, 35.05◦, 42.73◦, 53.37◦, 56.63◦, and 62.29◦, which attribute to the interplanar spacing or d value in angstrom with their (hkl) of 2.98 (220), 2.56 (311), 2.12 (400), 1.72 (422), 1.62 (511) and 1.49 (440), respectively. The peak values resemble with characteristic XRD peaks of Fe3O4 lattice with cubic spinal shape. The sharp peaks correspond to the high crystallinity of the magnetite. The particle size calculated using Scherrer equation was 24.18 nm, which is close to the value calculated by TEM images showing homogeneity in the particle sizes. The result has resembled with previously reported results [29,30].

**Figure 2.** XRD (X-ray diffraction) graph of Fe3O4 nanoparticles.
