Effect of valence electron spin polarization on the physical properties of CuCl2-filled poly(vinylidene fluoride) as a microwave modulator

Abstract

Infrared and optical spectra, differential thermal analysis, dc electrical resistivity, magnetic susceptibility, electron spin resonance, and microwave response of CuCl 2 -filled poly(vinylidene fluoride) (PVDF) films, over the filler mass fraction range 0.05 Յ W Յ 0.4, were measured. The infrared spectra evidenced the presence of ␤-phase, for all of the filler levels with main deformations of 20% (for W ϭ 0.25) and 30% (for other filler levels) head-to-head and tail-to-tail units, which were considered as polaron and bipolaron defects. Optical activity was mainly influenced by PVDF structure. Differential thermal analysis revealed dipole relaxation and premelting endothermic peaks. A quasi-one-dimensional interpolaron hopping was thought to proceed in the direct current electric conduction, with a hopping distance less than the distance between two successive head-to-head sites. A temperature-independent Pauli paramagnetic behavior was observed, confirming the presence of induced energy bands due to CuCl 2 filling. Most of the observed electron spin resonance signals were antisymmetric, with superimposed repels due to the hyperfine interactions characterizing PVDF. The obtained linear dependence of the isotropic hyperfine coupling constant (⌬A`), for Cu(II), on average g-factor, implied that ⌬A`is a measure of the valence electron spin polarization. An octahedral or distorted octahedral configuration was suggested for Cu(II). The present system is a good microwave modulator.

Characterization, electrical and magnetic properties of PVA films filled with FeCl3–MnCl2 mixed fillers

“…The magnetic susceptibility widely varies from the temperature-dependent magnetic susceptibility that follows the Curie-Weiss law or the Ising law, the temperature-independent Pauli parama gnetic (TIPP) susceptibility of the itinerant character to the temperature-independent diamagnetic susceptibility [5,6,[8][9][10]12]. Furthermore, electron spin resonance (ESR) spectroscopy provides a sensitive magnetic technique for detecting the unpaired electrons in the polymeric materials as well as determining the origin of the magnetic centers [6][7][8][9][10][11][12][13].…”

“…Moreover, different polymers such as poly(vinylidene fluoride) PVDF, polystyrene PS and polymethyl methacrylate PMMA were magnetically studied by Tawansi et al [5,6,[8][9][10]35]. Various magnetic properties were obtained according to the polymer, the type of the filler and the filling level.…”

“…Different concentrations of the fillers were applied in an attempt to modify the physical properties of the polymer under study and to obtain the desired filled polymer with distinct potential technological applications [3][4][5][6][7][8][9][10][11].…”

Characterization, electrical and magnetic properties of PVDF films filled with FeCl3 and MnCl2 mixed fillers

“…The main characterizing features of PVDF, previously reported in Ref. [30], are not observed in the present spectra. The PVDF hyperfine spectra disappeared and strong Lorentzian signals were observed which may be ascribed mainly to the Fe 3+ and/or Mn 2+ cluster coupled by strong spin-spin interaction.…”

Effect of equal amounts of Mn and Co dopant addition on the structural, electrical and magnetic properties of PVDF films

“…Recently, PVDF is widely used in biotechnology [2], photo-recording [3], microwave modulation [4] and in rechargeable lithium batteries [5]. Filling PVDF enhances its electromagnetic wave sensing feature due to its increased magnetic activity [6].…”