Synthesis, structural and magnetic characterization of the EuNbO2N oxynitride

EuNbO2N oxynitride was synthesized by nitridation of the EuNbO4 precursor oxide at 1113 K in ammonia flow for 12 h. X-ray powder diffraction data revealed that the EuNbO2N oxynitride crystallizes with the cubic perovskite-type structure, S.G. Pm3¯m and a lattice constant of a = 4.03244(10) Å. Thermogravimetric studies reveal that the oxynitride decomposes around 513 K under oxygen atmosphere, giving as a final product of decomposition the EuNbO4 oxide. The extremely low value obtained for remanence and coercive field fully agrees the isotropic character of the 8S7/2 ground state associated to the Eu2+. Magnetic susceptibility measurements indicate that EuNbO2N 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 Tc = 6.2 K. The saturation moment of 6.48 μB which is smaller than 7 μB expected for Eu2+ can be due to the presence of Eu3NbO7 impurity, confirmed by the X-ray powder diffraction data.

Magnetic susceptibility for the EuNbO2N oxynitride which behaves as a ferromagnet.Figure optionsDownload as PowerPoint slide