A facile method to develop electroactive β-phase in PVF₂ molecules by doping Au-nanoparticles in the form of nanocomposites for dielectric applications

Poly(vinylidene fluoride) (PVF₂) has emerged as a promising material for dielectric applications due to its excellent electrical and mechanical properties. However, maximizing the electroactive β-phase content in PVF₂ is crucial to enhance its dielectric performance. In this study, we propose a facile method to enhance the β-phase content in PVF₂ by doping gold nanoparticles (n-Au) (0–5 wt%) in the form of nanocomposites. The X-ray diffraction (XRD) patterns obtained for the annealed Au-PVF₂ films of Au-content specifically at 2 and 5 wt% exhibit a characteristic (200) peak of β-PVF₂, whereas non-annealed samples show diffraction peaks of (020) and (110) from a nanocrystalline α-PVF₂ phase. The Fourier transformed infrared spectroscopy (FTIR) study illustrates distinct absorption bands at 483 and 510, 834, and 880 cm⁻¹ characterize the formation of β-PVF₂ phase in respective Au-PVF₂ films compared to pure PVF₂ film which still contains IR bands of α-PVF₂ after annealing. Unambiguously, the gold inclusions induce a α → β-PVF₂ phase transformation. An enhanced dielectric constant value (ε_r-value), as large as 70 (i.e., an order of larger magnitude of the basic PVF₂ value), is found at low frequencies near 100 Hz after an optimized 2.0 wt% Au loading of a percolation threshold value. Our results reveal that these nanocomposites hold significant potential for applications in high-performance dielectric devices and energy storage systems requiring superior dielectric properties.