Frequency and temperature effects on dielectric and electrical characteristics of α-MnO2 nanorods

The alpha-MnO2 nanorods were successfully prepared by hydrothermal methods at 160 degrees C for 48 h. X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were employed to characterize the morphology and microstructure of the final product. The results show that the final product is the pure tetragonal alpha-MnO2 phase with rod-like nanostructure in diameters 30 nm and lengths up to 0.5-1 mu m. The dielectric and the electrical properties of the alpha-MnO2 nanorods were also analyzed and discussed at a range of the temperature from 223 K to 393 K. The dielectric constants and dielectric loss tangents both increase with the rising temperature and decrease with frequency. The electrical resistivity values also decrease with the rising temperature and frequency. It is also found that the dielectric loss of alpha-MnO2 mainly results from the space polarization and the temperature dependence of resistivity follows the Arrhenius Equation. (C) 2012 Elsevier B.V. All rights reserved.