LAUSR

Abstract Three dimensional graphene-hydroxyapatite (3DG-HA) powders were synthesized at various hydrothermal pressures and the effect of pressure change on the properties of the powder was investigated by the change in the volume of the solution. Graphene oxide, calcium nitrate tetrahydrate, and diammonium hydrogen phosphate solutions were used as a precursor to synthesis by hydrothermal method. The initial solution was prepared by mixing the precursors, and then the four samples P1, P2, P3, and P4 were identical with the same concentration, and fill percent of 16.67, 33.33, 66.67, and 83.33 in the hydrothermal conditions of 180 ᵒC, 8 h, pH = 11, and pressures at 13, 16, 21, and 19 bar for the above samples, respectively. The synthesized powders were characterized with Fourier-Transform Infrared spectroscopy (FT-IR), Field Emission Scanning Electron Microscope (FESEM), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Energy Dispersive Spectroscopy (EDS), and Raman spectroscopy. X-ray analysis results showed that increased pressure increased crystallinity and decreased crystallite size. FTIR and Raman spectroscopy analysis showed that the highest reduction rate for graphene oxide occurred at a fill percentage of 33.3. In general, when the fill percent ranged from 33% to about 75%, the efficiency of the hydrothermal process was appropriate for the synthesis of the 3dG-HA powders.