Thermochemical analysis on the growth of NiAl2O4 rods

Abstract

We have succeeded in growing cubic submicron-sized NiAl₂O₄ rods on sapphire substrates by means of heating a mixture of NiO and graphite powders. At 1600 °C, NiAl₂O₄ rods terminated by SiO_x-containing nanoparticles were grown on the sapphire substrates. In contrast, NiO rods grew randomly at 1500 °C. We elucidated the growth steps of cubic NiAl₂O₄ submicron-sized rods on the basis of a thermochemical approach, revealing the critical role of liquid silica that blocks the continuous loss of Ni to the vapor phase for the successful growth of NiAl₂O₄ rods.