Dielectric Behavior of Lithium Tantalate (LiTaO_3)/Poly(vinylidene fluoride) (PVDF) Nanocomposites Doped with MWCNTs

摘要

In this work, the authors have used the FT-IR, Raman spectral analysis and dielectric measurements to determine the characteristic properties of multi-walled carbon nanotubes (MWCNTs) doped the lead-free pyroelectric material; polyvinylidene fluoride (PVDF): lithium tantalate (LiTaO_3) (hereon referred as LT) nanocomposites. These nanocomposite thin films dielectric behaviour was characterized as a function of temperature and frequency. Deterministic characteristics of the FT-IR, Raman spectrum for both the nanocomposites; doped and undoped were observed. Values of both ε' and ε" are high at lower frequency and decrease with an increase of frequencies due to polarization effects Samples, ranging from 15-280 microns in thickness, were measured in the temperature range from room temperature to 20 to 90 °C. All results showed that MWNTs-were covalently linked with the blend through C-C bonds. The temperature dependent pyrovoltage and figure of merits derived from pyroelectric coefficient and dielectric measurements were presented. The addition of MWCNTs increases and enhances the conductivity attributed to charge carrier build up and increases in segmental mobility of polymeric chains. The samples were prepared by the solution casting technique. Measures indicate that at as the temperatures vary both the dielectric constants increase with the MWCNT doping these quantities increase at least 10 times. Our MWCNTs doped PVDF + LT thin films yield higher figures of merit compared to PVDF + LT thin films and results indicate a efficient usage of MWCNTs doped PVDF+LT thin films in multi-device applications.