Controllable decomposition of lanthanum oxychloride through different annealing conditions

Abstract Monolithic Lanthanum (La)-based aerogels were successfully synthesized by using the facile epoxide addition method. The as-prepared La-based aerogels were then annealed under different annealing conditions (temperature and atmosphere). The scanning electron microscopy images indicate that the as-prepared La-based aerogels are nanoporous amorphous materials with a density of ∼60 mg cm −3 . Powder X-ray diffraction confirmed that lanthanum oxychloride (LaOCl) particles were formed at 500 °C in both static air and N 2 , and decomposed to La 2 O 3 at ∼700 °C in static air but remained stable until ∼900 °C in N 2 . At 1050 °C, the LaOCl particles were completely converted to La 2 O 3 particles in static air, while under a nitrogen atmosphere the material retained the LaOCl structure well until a conversion to the oxide. These conversions were further explored using Fourier transform infrared and photoluminescence spectroscopy. Lastly, the influence of annealing conditions on the microstructure and porosity of the La-based aerogels were also investigated.