A novel LaFeO3−XNX oxynitride. Synthesis and characterization

Highlights: ► LaFeO3 perovskite synthesized by auto combustion method. ► LaFeO3−XNX oxynitride produced by ammonolysis reaction. ► Oxynitride characterized by XRD, Rietveld, SEM, EDX, BET, Raman, TGA and FTIR. ► Partial replacement of oxygen by nitrogen increases slightly the cell parameters. ► TGA shows that oxynitride start to decompose in air above 550 °C. Evolution of N2 and NO was detected. - Abstract: A perovskite LaFeO3 was synthesized by auto combustion method and then LaFeO3−XNX oxynitride was produced by ammonolysis reaction. The synthesized LaFeO3−XNX oxynitride was characterized by X-ray diffraction (XRD), Rietveld refinement, scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Brunauer–Emmett–Teller (BET) nitrogen adsorption, particle size distribution, Raman spectroscopy, thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). Nitrogen effect into the perovskite structure was confirmed by DRX. The structure refinement using the Rietveld method indicates that partial replacement of oxygen by nitrogen increases slightly the cell parameters of the LaFeO3 perovskite. FTIR analysis show that bands at 995 and 1070 cm−1 in the oxynitrides spectra could be assigned to the stretching vibration modes of Fe–N bonds in the FeO6−XNX octahedral. Thermogravimetric analysis (TGA) showed that LaFeO3−XNX oxynitride series start to decompose in air above 550 °C. During the decomposition it was found that some amount of nitrogen stays retained in the structure forming intermediate compounds. MS analysis of the gaseous products reveals the evolution of N2 and NO, suggesting a complex reaction mechanism. To our knowledge, there are no reports on the synthesis and characterization of the LaFeO3−XNX oxynitrides.