Structure, Electrical and Magnetic properties of Sm_1-xCa_xCrO₃, orthochromites

We have synthesized Sm_1-xCa_xCrO₃ chromite and investigated the influence of calcium (Ca) doping at Sm-sites on the crystal structure, magnetic and electrical properties in a series of compounds in the 0≤x≤2.0 range. No structural transition was observed in this composition range and the doped compound crystallized into distorted orthorhombic structure with Pnma space group, which was confirmed by Rietveld refinement using M_o-K_α X-ray radiation. Samples of the Sm_1-xCa_xCrO₃ series (x=0.0, 0.02, 0.04, 0.10 and 0.20) were prepared by Pechini polymeric precursor method and the polycrystalline samples were characterized by X-ray photoelectron spectroscopy (XPS), Magnetization vs. Temperature measurements, UV-Vis spectroscopy and electrical measurements (10-300 K). The effect of Sm substitution by Ca has important effect on the cell volume; the antiferromagnetic transition decreases from T_N= 193K (x=0) to 150K (x=0.20) and the magnetization reversal also decreases from 35K (x=0) to 9K (x=0.20). These changes in magnetic behavior of Sm_1-xCa_xCrO₃ can be associated with the Cr(VI) content in samples.