Synthesis of rGO-reinforced MgAl 2 O 4 spinel composites by solid-state powder route mechanism: A comparative analysis between non-reinforced and rGO-reinforced spinel composites

Abstract

Reduced Graphene Oxide (rGO)-reinforced MgAl 2 O 4 spinel composite was successfully synthesized by a solidstate powder route mechanism via high-energy planetary ball milling of corresponding metal oxide precursors followed by a high -temperature single -stage sintering process. The effect of rGO on the homogeneity, phase development, morphology, chemical composition, rate of formation of spinel, and cation anti -site formation of the composites was methodically investigated. For comparison, a stoichiometric non -reinforced MgAl 2 O 4 spinel was also synthesized. The addition of 0.2 wt% and 0.4 wt% of rGO as reinforcement increased the homogeneity of the ball -milled composite powder, with Polydispersity Index (PDI) values of 0.19 and 0.15 respectively, as compared to 0.24 obtained in non -reinforced spinel composite. The X-ray diffraction pattern and IR spectrum of 1650 degrees C sintered composites confirmed the formation of highly crystalline phases with spinel structure. The microstructural analysis revealed that the addition of rGO led to a reduction in porosity and improved the process of sintering. Calorimetric studies showed that spinelization started to occur at 858 degrees C and 880 degrees C for 0.2 wt% and 0.4 wt% rGO-reinforced composites respectively, which was faster than non -reinforced composite. 27 Al solid -sate nuclear magnetic resonance (SS-NMR) analysis depicted that ceramic composite reinforced with rGO exhibited lesser inversion parameter of 0.09 (for 0.2 wt% rGO) and 0.055 (for 0.4 wt% rGO), as compared to 0.145 obtained in non -reinforced composite, indicating lesser cation anti -sites formation in rGO-reinforced spinel composite.