Mechanical Activation and Cation Site Disorder in MgAl2O4

Abstract

The synthesis and crystallographic site occupancy were investigated for MgAl2O4 with and without mechanical activation of the precursor powders. Heating to 1200 °C or higher resulted in the formation of a single spinel phase regardless of whether the powders were mechanically activated or not. Neutron diffraction analysis was used to determine cation site occupancy and revealed that mechanical activation resulted in a lower degree of cation site inversion compared to the nonactivated materials, which indicated that the powders were closer to thermodynamic equilibrium. This is the first study to characterize the effects of mechanical activation on crystallographic site occupancy in magnesium aluminate spinel using neutron diffraction.

Formation of TiB2–MgAl2O4 Composites by SHS Metallurgy

“…Moreover, a recent study showed that TiB 2 –Al 2 O 3 –MgAl 2 O 4 composite possesses temperature insensitive and enhanced microwave absorption properties [ 11 ]. Magnesium aluminate spinel, MgAl 2 O 4 , as an additive has been rarely studied, possibly because the fabrication of MgAl 2 O 4 via either the direct solid-state reaction of oxides or wet chemical methods requires multiple steps that are complicated and time-consuming [ 12 , 13 , 14 ]. However, MgAl 2 O 4 is an attractive component due to its high melting point, chemical inertness, high hardness, corrosion resistance, high mechanical strength, and low cost [ 12 ].…”

Solid-State Reaction Synthesis of MgAl2O4 Spinel from MgO–Al2O3 Composite Particles Prepared via Electrostatic Adsorption

“…Bead milling (BM) is a common method for preparing the initial mixture for MAS synthesis. Recently, this method has been used to fabricate γ-Al 2 O 3 + MgO, θ/α-Al 2 O 3 + MgO, α-Al 2 O 3 and MgO nanopowders as well as MgO–Al 2 O 3 –GeO 2 mixtures. − Mechanical activation is an important method for reducing particle sizes, shortening diffusion lengths, and accelerating reactions. − Moreover, material deformation and defect formation also occur during mechanical activation, which generally increases the free energy of the system.…”

“… 15 − 17 Mechanical activation is an important method for reducing particle sizes, shortening diffusion lengths, and accelerating reactions. 18 − 21 Moreover, material deformation and defect formation also occur during mechanical activation, which generally increases the free energy of the system.…”