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

The α-MnO2 nanorods were successfully prepared by hydrothermal methods at 160 °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 α-MnO2 phase with rod-like nanostructure in diameters 30 nm and lengths up to 0.5–1 μm. The dielectric and the electrical properties of the α-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 α-MnO2 mainly results from the space polarization and the temperature dependence of resistivity follows the Arrhenius Equation.

The α-MnO2 nanorods with diameters of 30 nm and lengths up to 0.5–1 μm were prepared with hydrothermal methods. The nanorods have smooth and flat surfaces.The curves of correlation between the reciprocal of temperature (1000/T) and the logarithm of electric resistivity (log ρ) are found anomalies at about 303 K despite the frequencies tested.Figure optionsDownload as PowerPoint slideHighlights
► The α-MnO2 nanorods were prepared with hydrothermal methods.
► The nanorods are with diameters of 30 nm and lengths up to 0.5–1 μm.
► The dielectric properties increase with temperature but decrease with frequency.
► The logarithm curves of electric resistivity are found anomalies at about 303 K.