Thermal Stability And Decomposition Kinetics Of Ndnio3-Delta At 1 Bar Of O-2

Despite the interest in rare-earth nickelates for applications, their processing under 1 bar of oxygen pressure is still challenging. In this work, we report the co-precipitation synthesis, thermal stability and thermally driven decomposition of NdNiO3 phase, in order to determine the synthesis parameters towards a pure perovskite phase. We concluded that using a 1% molar excess of Nd during preparation and posterior annealing at around 900 degrees C at 1 bar of O-2 yields an almost pure NdNiO3-delta phase (with a hexagonal Nd2O3 phase below 0.6% molar), with an oxygen deficiency of delta = 0.082 +/- 0.001. The decomposition of the NdNiO3-delta phase into Nd4Ni3O10 and NiO was found to start above 900 degrees C. On further heating, above 1050 degrees C, the Nd4Ni3O10 decomposes into Nd2NiO4 and NiO phases. Structural parameters and Raman spectra are provided for the NdNiO3, Nd4Ni3O10 and Nd2NiO4 compounds.