Preparation of LaTiO2N Using Hydrothermally Synthesized La2Ti2O7 as a Precursor and Urea as a Nitriding Agent

A facile method was successfully developed to prepare perovskite-type metal oxynitrides, LaTiO2N, from La2Ti2O7 as a precursor in an atmosphere of N-2. Urea was employed as a solid-state nitriding agent, instead of gaseous NH3, to increase the safety of the reaction. The hydrothermally prepared La2Ti2O7 precursor had a nanosheet morphology and contained La(OH)(3) as a by-product. Through the optimization of reaction conditions including heat-treatment temperature and content of urea, single-phase LaTiO2N could be obtained. In addition, we revealed that the La(OH)(3) present in the La2Ti2O7 precursor played an important role in the nitriding process using urea. La2O2CN2 was generated by the reaction of La(OH)(3) with the thermal decomposition products of urea at the medium temperature range. This indicated that the NH3 gas released from the thermal decomposition of urea did not directly cause nitridation of the La2Ti2O7 precursor.