The rare earth vanadium oxynitride perovskites RVO3-x Nx (R = La, Pr, Nd; 0 ≤ x ≤ 1) have been prepared by treatment of RVO4 precursors in NH3. The ammonolysis reactions proceed through an initial reduction of RVO4 precursors to RVO3 perovskites that are progressively nitrided and reoxidised to RVO3-x Nx materials with varying proportions of V4+/V3+. Variable temperature neutron diffraction studies show that NdVO2N and PrVO2.24N0.76 have orthorhombic Pbnm symmetry between 3.5 and 300 K, but LaVO 2.11 N 0.89 undergoes a broad Pbnm to R3c structural transition over this temperature range. In LaVO 3-x Nx samples the proportion of the R3c phase at room temperature increases with the nitrogen content. The partial anion order indicative of planes of cis-VN2 chains found in NdVO2N is also present in PrVO 2.24 N 0.76, and is thus robust to the disorder created by non-stoichiometry. Magnetic measurements reveal spin freezing transitions at low temperatures in LaVO 2.09 N0.91 and PrVO2.24N0.76, but NdVO2N is paramagnetic.
|Number of pages||9|
|Journal||Journal of Materials Chemistry C Materials for optical and electronic devices|
|Early online date||13 Jan 2014|
|Publication status||Published - 28 Mar 2014|