Preparation of Ultra-fine La_3NbO_7 Powder by Solid State Reaction

摘要

As a new candidate material for the ceramic layer in thermal barrier coatings (TBCs) system, La_3NbO_7 was synthesized with La_2O_3 powder and Nb_2O_5 powder by solid state reaction. The starting powders with a mole ratio of La to Nb of 3:1 were mixed and then the mixture was calcined under the different temperatures (800°C, 1000°C, 1200°C) and dwell times (2h, 6h, lOh). The phase structure of the powder was observed by X-ray diffraction (XRD), and the microstructure of the sample was observed by scanning electron microscope (SEM). The effect of calcination temperature and dwell time on the phase formation were examined. The results indicate that the La_3NbO_7 powder with single phase can be synthesized successfully at 1200°C for 10h in air, and the La_3NbO_7 powders synthesized have an ultra-fine particle size of 0.5-1 um with a granular particle shape. With the temperature increasing, LaNbO_4 was synthesized firstly and then La_3NbO_7 was synthesized with a mole ratio of La_2O_3 to LaNbO_4 of 1:1.