Effect of 80 MeV O6+ ion irradiation on structural, morphological, dielectric, and ferroelectric properties of (1-x)PVDF/(x)BaTiO3 nanocomposites

Abstract

The polyvinylidene fluoride/barium titanate (1-x)PVDF/(x)BaTiO3 nanocomposite films (x = 0.2 and 0.5) were prepared by solution mixing method. The dielectric constant (e′) was increased by the BaTiO3 incorporation in the PVDF matrix. The pristine PVDF and nanocomposite films were uniformly irradiated with 80 MeV O6+ ion beam over an area of 1 cm2 at room temperature under the high vacuum of ~ 5 × 10−6 Torr with ion fluences, 5 × 1010, 2 × 1011, and 2 × 1012 ions/cm2. After irradiation, recrystallization and α→β phase transition were observed in PVDF through X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy analysis. However, almost complete amorphization was observed in BaTiO3 filler in (1-x)PVDF/(x)BaTiO3 nanocomposite samples. After irradiation, the dielectric constant (e′) increases at lower fluence (5 × 1010 ions/cm2) while decreases at higher fluence (2 × 1012 ions/cm2) as compared with the pristine samples. The creation of free radicals in PVDF due to chain scission and crosslinking observed upon irradiation is responsible for the observed behavior of dielectric constant (e′). While in nanocomposites, the change in the dielectric properties of BaTiO3 in nanocomposites samples after irradiation can be associated with the radiation-induced amorphization of BaTiO3. After irradiation, both the remanence polarization and coercive field increase for PVDF while decrease for nanocomposite samples. The observation of amorphousity in BaTiO3 phase through swift heavy ion irradiation is interesting and important from a fundamental point of view.