Preparation of nano-sized lutetium aluminum garnet powders using ammonia hydrogen carbonate as precipitant

Nano-sized lutetium aluminum garnet (Lu₃Al₅O ₁₂, LuAG) powder was co-precipitated from a mixed solution of aluminum and lutetium nitrates using ammonia hydrogen carbonate (AHC) as precipitant. The component, phase evolution and thermal decomposition of the precursor during calcination were studied by FTIR, XRD and TG-DSC The particle size and morphology of the synthesized powders were determined by TEM. It was found that the precursor was amorphous carbonate and transformed to pure LuAG phase after being calcined at 900°C for 2 h. LuAG crystallite grew with increasing calcined temperature. The crystallization stage was characterized by an exothermic peak of DSC curve at 1064°C. This temperature was higher than that detected by XRD, which was caused by the difference in soaking time and the hysteresis of the TG-DSC analyzer. The resultant LuAG powders were loosely agglomerated with an average particle size 50nm. However, the addition of small amount of hydroxypropyl cellulose (HPC) as dispersant can reduce the agglomeration and particle size of the produced LuAG powders. The size of LuAG powder is about 30nm in the presence of HPC.