Comparison of preparation and formation mechanism of LuAG nanopowders using two different methods

Lutetium aluminium garnet (LuAG) nanopowders were synthesised by co-precipitation method and solvothermal method. Phase identification, thermal stability, morphologies, particle sizes, size distributions and the mean of grains were characterised by X-ray powder diffraction, thermogravimetric/differential thermal analysis, transmission electron microscope and dynamic light scattering, respectively. The results show that the pure LuAG nanopowders can be obtained by two methods; however, the formation mechanism and morphology evolution of nanopowders prepared by various processes are quite different. It is deduced that the solid-phase diffusion mechanism is applied in the co-precipitation process. Owing to the high-temperature treatment above 900°C, the LuAG nanopowders produced by co-precipitation method have large size with serious agglomeration. The spherical LuAG nanopowders with good dispersivity, no aggregation, fine grains and a relatively narrow grain size distribution are prepared by solvothermal method, which belongs to the dissolution-crystallisation mechanism. Based on the above comparison, it can be inferred that the LuAG nanopowders obtained by solvothermal method are beneficial for the compaction and the sintering of transparent ceramics with high density.