Structural, magnetic, and electrical features of the Nd sub(2)SrMn sub(2)TiO sub(9) perovskite-like compound

The synthesis process of the polycrystalline ceramic compound Nd sub(2)SrMn sub(2)TiO sub(9) by means of the solid-state reaction procedure is reported. The crystalline structure was analyzed through X-ray diffraction experiments in the Bragg-Brentano recipe. The Rietveld refinement of the diffraction pattern by using the GSAS code shows that this material crystallizes in an orthorhombic structure, space group Pnma (#62), with lattice parameters a=5.4764(6), b=7.7468(6), and 5.4810(6). The surface morphology was studied by scanning electron microscopy images, which evidence the formation and compacting of grain with mean size 352.63nm. Semiquantitative compositional analysis performed by means of Energy Dispersive X-ray Spectroscopy shows the stoichiometric composition of the samples. Measurements of magnetization as a function of temperature reveal that this compound has a ferromagnetic behavior. The analysis with the Curie equation permitted to establish an effective magnetic moment mu sub(eff)=4.33 mu sub(B), which is 95.7% in agreement with the theoretical value expected from the Hund's rules. Measurements of DC resistivity as a function of temperature show a conductor behavior below the Curie temperature and insulator above. Evidences of a nonlinear response as a function of frequency with high values of relative dielectric constant reveal the occurrence of giant dielectric constant with sub(r)=6480 for nu =100Hz.