Study on dielectric properties of TiO<inf>2</inf>/XLPE nanocomposites

Abstract

This paper focuses on the dielectric properties in TiO 2 /XLPE nanocomposites, the TiO 2 nanoparticles were added into XLPE matrix with different mass concentrations (1wt%, 3wt%, and 5wt%). It was found that the volume resistivity of TiO 2 /XLPE nanocomposites was higher than XLPE, which increased with filling concentrations. In addition, the TiO 2 /XLPE nanocomposites had lower permittivity and lower dielectric dissipation, which increased with the filling concentrations and decreased with the measured frequency. The results of pulsed electro-acoustic (PEA) measurements showed that the total space charge was suppressed and heterocharge disappeared in TiO 2 /XLPE nanocomposites, leaving a small amount of negative charge in middle of samples. According to the analysis in this paper, new interface regions introduced many deep traps due to filling TiO 2 nanoparticles, which can shorten the effective distance of “solitary waves” migration and greatly reduce carrier mobility. On the other hand, low carrier mobility enhance the recombination process and weaken the ionization process of impurities, leading to the disappearance of heterocharge in TiO 2 /XLPE. Furthermore, the interface reverse electric field not only suppress the charge injecting from the electrodes, but also strengthen the electric field in the middle of matrix, so that the accumulated space charge can be transferred out of material timely.