Crystal structure and impedance study of samarium substituted perovskite: La1−xSmxMnO3 (x = 0.1–0.3)

Three perovskite structured ceramic phases- La1−xSmxMnO3 (where x = 0.1, 0.2 and 0.3) synthesised by solid-state-reaction route crystallize in the rhombohedral symmetry (space group R-3c). The structure refinement converged to satisfactory values of the Rietveld parameters: Rp, Rwp and goodness of fit. The unit cell volume decreases slightly with increasing mole% of samarium in lanthanum manganite matrix. The M–O stretching and bending vibrations in the infrared region have been assigned. Morphology and compositional analysis have been carried out by scanning electron microscopy (SEM) and Energy Dispersive X-ray Analysis (EDAX) of the specimens. The electrical properties have been investigated by impedance spectroscopy in the frequency range 42 Hz–5 MHz at temperatures between 50° and 300 °C. Nyquist plots show the dominance of grain contribution and Debye like relaxation in the material. The compounds exhibit composition dependent Arrhenius-type of electrical conductivity.

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