Effect of valence electron spin polarization on the physical properties of CuCl2-filled poly(vinylidene fluoride) as a microwave modulator
✍ Scribed by A. Tawansi; M. I. Ayad; E. M. Abdel-Razek
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 281 KB
- Volume
- 72
- Category
- Article
- ISSN
- 0021-8995
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✦ Synopsis
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 ⌬Ais 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.