Size-manipulat ion, compacti on and electrical properties of barium manganite nanorods synthesized via the CHM method

A composite-hydroxide mediated method was employed to synthesize barium manganite nanorods. Diameter, surface smoothness and uniformity of these nanorods were optimized by varying reaction temperature and reaction time. The rods with an average diameter of 200 nm and length of 1–1.5 μm were obtained at optimum conditions of 200 °C/48 h. The dielectric study of these rods reveals that they have higher value of dielectric constant at lower frequencies which was attributed to the interfacial and rotational type polarizations. Similarly, the increase in dielectric constant with temperature was attributed to the thermal activation of such polarizations. Furthermore, the analysis of ln(J) vs. E^1/2 characteristics in the temperature range of 300–400 K shows that possible operative conduction mechanism was of Poole–Frenkel type. The value of β_exp was found to be 4.85 times greater than the expected theoretical value of field lowering coefficient with an internal field enhancement factor of α²=23.5. This high value of β_exp may be due to some localized electric fields existing inside the sample.