Synthesis of nano-sized spinel (MgAl2O4) from short mechanochemically activated chloride precursors and its sintering behavior

• New reagent compounds were introduced for mechanochemical synthesis of nano-spinel.
• A mechanochemical solid-state reaction was used for the production of spinel precursor.
• A short time high energy milling was employed for nano-structure spinel synthesis.
• The single phase powder was found to consist mainly of particles smaller than 12 nm.
• The MgAl2O4 has high surface area and were sintered to ∼94% of theoretical density.

MgAl2O4 is the most important compound in the MgO–Al2O3 system which can be produced through various methods. In the present work, synthesis and sintering behaviour of nano-sized spinel powder produced through mechano-chemical process were studied. For this purpose, MgCl2⋅6H2O, AlCl3⋅6H2O, and NaOH reagents altogether with a small amount of water were mixed and subjected to high-energy ball milling for a short time (∼10 min). After confirming the occurrence of solid-phase displacement reactions by X-ray diffraction, the as-milled powders were washed, dried and then heated from 400 °C to 1200 °C for 2 h. The heated powders were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, simultaneous thermal analysis, BET and transmission electron microscopy techniques. It was found that pure nano-sized spinel phase, with 8–12 nm mean particle size and 76.9 m2/g specific surface area is obtainable through heating the precursor for 2 h at 800 °C. The synthesized powders were sintered at 1500 °C and obtained 93.8% of the theoretical density.

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