Molten salt synthesis of LaAlO3 powder at low temperatures

Rhombohedral LaAlO₃ powder was synthesised by reacting equimolar La₂O₃ and Al₂O₃ in a molten KF–KCl eutectic salt for 3 h between 630 and 800 °C. The lowest synthesis temperature (630 °C) is about 1000 °C lower than that of conventional mixed oxide synthesis, and close to or lower than those used by most wet chemical methods. The LaAlO₃ particle size increased from <3 to 3–7 μm with increasing temperature from 630 to 700 °C, but changed little on further increasing temperature to 800 °C. On the other hand, it decreased with increasing salt/oxide weight ratio from 1:1 to 6:1. The “dissolution–precipitation” mechanism played a dominant role in the molten salt synthesis of LaAlO₃.