Characterization and humidity properties of MgAl2O4 powders synthesized in a mixed salt composed of KOH and KCl

In this paper, we have tried to prepare MgAl 2 O 4 spinel by molten salt synthesis using hydroxide as solvent. By controlling the amount of KCl in KOH, pure flower-like MgAl 2 O 4 nanostructures could be synthesized at 1150 °C. Powder X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy were used to investigate the structures and morphologies of the obtained products. The results showed that the 3D flower-like nanostructures consisted of numerous 2D nanoflakes with a thickness of about several tens of nanometers. Further investigations on the possible formation mechanism revealed that a self-sacrificing template process dominated the formation of MgAl 2 O 4 and the growth of the flower-like products was attributed to the competition between the growth rates along the directions perpendicular and parallel to the Al 2 O 3 particle surfaces. Finally, an impedance-type humidity sensor was fabricated based on the flower-like MgAl 2 O 4 nanostructures and tested for its humidity performance showing that the as-prepared MgAl 2 O 4 nanostructures are suitable for high-performance humidity sensors. In this paper, we have tried to prepare MgAl 2 O 4 spinel by molten salt synthesis using hydroxide as solvent.