Mechanochemical preparation of a modified NiAl₂O₄ structure

Area of Science:

• Materials Science
• Solid-State Chemistry
• Nanotechnology

Background:

• Mechanochemical synthesis offers a sustainable and simple route for material preparation.
• Nickel aluminate (NiAl2O4) is a material with potential applications in catalysis and electronics.
• Understanding the influence of synthesis parameters on material properties is crucial for optimizing performance.

Purpose of the Study:

• To investigate the effects of varying milling energies on the phase, chemical environment, and surface composition of NiAl2O4.
• To explore the thermal decomposition and structural changes of NiAl2O4 synthesized via mechanochemical methods.
• To characterize the disordered, partially inverse spinel structure of the synthesized NiAl2O4.

Main Methods:

• High-energy planetary milling for mechanochemical activation.
• Calcination at different temperatures (750°C and 900°C).
• Characterization using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), solid-state UV-Visible spectroscopy (SS-UV-VIS), nuclear magnetic resonance (NMR), high-resolution transmission electron microscopy (HR-TEM), and thermal gravimetry-differential scanning calorimetry (TGA-DSC).

Main Results:

• Milling energy significantly influences the phase, chemical environment, and surface composition of NiAl2O4.
• Calcination at 750°C and 900°C resulted in a mixed NiAl2O4:NiO phase.
• The surface of the material was found to be enriched with Nickel (Ni) and remained relatively stable across the studied calcination temperatures.

Conclusions:

• Mechanochemical synthesis combined with calcination provides a viable route to NiAl2O4 with tunable properties.
• The study elucidates the disordered, partially inverse spinel structure of NiAl2O4.
• The Ni-enriched surface stability suggests potential for applications requiring surface-specific interactions.