Synthesis and characterization of MgAl2O4 micro-rods by a molten salt method

Large amounts of MgAl2O4 micro-rods were successfully synthesized using the molten-salt technology. The effect of KCl contents on the formation of MgAl2O4 micro-rods was investigated. The structure and morphology of MgAl2O4 were investigated by means of powder X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy, respectively. The experimental results showed that the contents of KCl significantly influenced the formation of MgAl2O4 micro-rods. MgAl2O4 micro-rods could be prepared at 1150 °C with a weight ratio of 100:1 between the salt and the starting materials. The formation of MgAl2O4 micro-rods could be suggested to be due to the inhomogeneous nucleation and orientated growth perpendicularly to the surfaces of Al2O3 grains. An impedance-type humidity sensor was finally fabricated based on the as-prepared MgAl2O4 micro-rods. According to tests of the humidity performance, MgAl2O4 micro-rods might be suitable for high-performance humidity sensors.