Synthesis, structural and magnetic characterization of the EuNbO2N oxynitride

EuNbO 2 N oxynitride was synthesized by nitridation of the EuNbO 4 precursor oxide at 1113 K in ammonia flow for 12 h. X-ray powder diffraction data revealed that the EuNbO 2 N oxynitride crystallizes with the cubic perovskite-type structure, S.G. P m 3 ¯ m and a lattice constant of a = 4.03244(10) A. Thermogravimetric studies reveal that the oxynitride decomposes around 513 K under oxygen atmosphere, giving as a final product of decomposition the EuNbO 4 oxide. The extremely low value obtained for remanence and coercive field fully agrees the isotropic character of the 8 S 7/2 ground state associated to the Eu 2+ . Magnetic susceptibility measurements indicate that EuNbO 2 N behaves as paramagnetic over temperature range 10–300 K, the sudden increase in the susceptibility observed below 10 K, is characteristic of the onset of a ferromagnetic behaviour with an estimated T c = 6.2 K. The saturation moment of 6.48 μ B which is smaller than 7 μ B expected for Eu 2+ can be due to the presence of Eu 3 NbO 7 impurity, confirmed by the X-ray powder diffraction data.