Enhanced physical properties of γ-Al₂O₃-rGO hybrids prepared by solvothermal and hot-press processing

In this study, a solvothermal method was employed for the first time to fabricate hybrids composed of cross-linked γ-Al₂O₃ nanorods and reduced graphite oxide (rGO) platelets. After calcination and hot-press processing, monoliths of Al₂O₃-rGO hybrids were obtained with improved physical properties. It was found that the oxygen-containing groups on graphene oxide were beneficial for the adsorption of aluminum isopropoxide, leading to a uniform dispersion of rGO with Al₂O₃, which was obtained by hydrolysis of aluminum isopropoxide during the solvothermal reaction. The hybrid, which was subsequently calcinated for 3 h showed electrical conductivity of 6.7 × 10¹ S m^-1 together with 90% higher mechanical tensile strength and 80% higher thermal conductivity as compared to the bare Al₂O₃. In addition, the dielectric constant of the hybrid was 12 times higher than that of the bare Al₂O₃. In this study, the highest values of electrical conductivity (8.2 × 10¹ S m^-1), thermal conductivity (2.53 W m^-1 K^-1), dielectric constant (10⁴) and Young's modulus (3.7 GPa) were obtained for the alumina-rGO hybrid calcinated for 1 h. XRD characterization showed that an increase in calcination temperature and further hot-press processing at 900 °C led to enhanced crystallinity in the γ-Al₂O₃ nanorods in the hybrid, resulting in enhanced physical properties in the hybrids.