Controllable decomposition of lanthanum oxychloride through different annealing conditions

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 N2, and decomposed to La2O3 at ∼700 °C in static air but remained stable until ∼900 °C in N2. At 1050 °C, the LaOCl particles were completely converted to La2O3 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. •The phase, composition and microstructure of La-based aerogel can be controlled.•The emission peaks and PL intensity of Eu3+-doped La-based aerogel can be controlled.•The decomposition of LaOCl phase can be delayed in N2 atmosphere.