Electrical characteristics of PVDF/BTO nanocomoposites under DC voltage application

The breakdown strength, conduction current, and space charge distribution were measured to understand the electrical characteristics of polyvinylidene fluoride (PVDF) / barium titanium (IV) oxide (BTO) nanocomposites under DC voltage applications. The breakdown strength of PVDF with a BTO nanofiller was almost same regardless of a BTO content but the breakdown strength of PVDF with a BTO nanofiller was lower than that without a BTO nanofiller. The conduction current of PVDF with a BTO nanofiller also increase, compared to that without a BTO nanofiller, suggesting that the increased conduction current due to the increase in some carriers related to the addition of a BTO nanofiller leads to breakdown. In the space charge measurement, the induced charge polarities on PVDF with a BTO nanofiller were reversed compared to the applied voltage. The magnitude of the pressure wave from the surface polarization charge generated at the interface between the electrode and the sample increased qualitatively compared to that from the induced charge. The negative space charge was accumulated in the bulk of PVDF with a BTO nanofiller just prior to the voltage application and the negative space charge in the bulk decreased as the voltage application time increased. From these results, it was suggested that the breakdown was due to the increase in the conduction current, which is controlled by the space charge.