Dielectric relaxation in polyaniline–polyvinyl alcohol composites

Dutta, Partha; Biswas, Subhajit; De, S. K.

doi:10.1016/s0025-5408(01)00813-3

Cited by 171 publications

(80 citation statements)

References 8 publications

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“…Nevertheless, for a high range of frequency, these dipoles begin to lag the external field, and the value of εʹ tends to change slightly. This indicates a saturation state in the polarization [45]. The εʹ values are increasing by raising synthesis temperature, whereas they are decreasing by an increase in the frequency.…”

Section: Electric and Dielectric Properties Of Nickel-cobalt Oxide Namentioning

confidence: 92%

“…It reaches its lowest value for the sample prepared at the highest temperature (450˝C). This phenomenon is related to low numbers of charge carriers (lack of free charge motion) in specimens prepared at higher temperature that in turn leads to a decrease in the dielectric loss value [45][46][47]. Interestingly, the high observed value of ε 1 at a low frequency range may be the consequence of the interfacial effect of the electrodes and the sample (DC barrier effect) [48].…”

Section: Electric and Dielectric Properties Of Nickel-cobalt Oxide Namentioning

confidence: 99%

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Structure and Physical Properties of NiO/Co3O4 Nanoparticles

Naseri

Dehzangi²,

Kamari

et al. 2016

Metals

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Abstract:The thermal treatment method was employed to prepare nickel-cobalt oxide (NiO/Co 3 O 4 ) nanoparticles. This method was attempted to achieve the higher homogeneity of the final product. Specimens of nickel-cobalt oxide were characterized by various experimental techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). X-ray diffraction results showed that there was no crystallinity in the predecessor, and it still had the amorphous phase. The formations of the crystalline phases of the nickel-cobalt oxide nanoparticles started from 350-500˝C, and the final products had different crystallite sizes ranging from 11-35 nm. Furthermore, the variation of DC conductivity (σ dc ), impedance, tangent loss (tgδ) and dielectric constant (ε 1 ) of the calcined specimens with frequency in the range of 10 2 -10 6 Hz was investigated. σ dc showed a value of 1.9ˆ10´6 S/m, 1.3ˆ10´6 S/m and 1.6ˆ10´6 S/m for the specimens calcined at 350, 400 and 450˝C, respectively. Additionally, a decrease in tgδ values with an increase in temperature was observed. Finally, the formed nanoparticles exhibited ferromagnetic behaviors, which were confirmed by using a vibrating sample magnetometer (VSM).

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Section: Electric and Dielectric Properties Of Nickel-cobalt Oxide Namentioning

confidence: 92%

Section: Electric and Dielectric Properties Of Nickel-cobalt Oxide Namentioning

confidence: 99%

Structure and Physical Properties of NiO/Co3O4 Nanoparticles

Naseri

Dehzangi²,

Kamari

et al. 2016

Metals

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“…The electrical properties of the PANI:Cr +3 /PVA were evaluated by impedance spectroscopy measurements [5]. Through electrical measurements, the dielectric constant, dielectric loss and other material properties could be obtained.…”

Section: Methodsmentioning

confidence: 99%

AC electrical conductivity of Cr-doped polyaniline/poly(vinyl alcohol) blends

et al. 2004

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Polyaniline (PANI) and their charge transfer complexes are engineering materials that continue to attract considerable attention from engineers due to their unique electrochemical behavior, environmental stability and high degree of processability. Extensive works on the preparation of electrically conductive PANI blends containing a polymeric matrix having desirable physical and good mechanical characteristics have pointed as a promising route to overcome the PANI intractabilities. This paper reports the electrical properties of the dichromated PANI/poly(vinyl alcohol) (PANI:Cr 3+ /PVA) blends. Doped polyaniline powder in the emeraldine base form was synthesized by the classical chemical oxidation of aniline with ammonium persulfate as the oxidant in the presence of chromium (Cr 3+ ). The SEM (Phillips XL 30) was used to understand the changes occurring in the conductivity to a microstructure level. The distribution of PANI:Cr 3+ (50% w/w) in the host polymer (PVA) show some tendency to occur in "flocculated structures". The samples were cut into circular shapes to form films about 500 microns thick. Electrical contacts were made by sputtering gold over sample surfaces. We have carried out impedance spectroscopy measurements in the range of 20Hz to 1MHz. Measurements carried at 100K and 250K indicates that thermally activated carrier process between PANI:Cr 3+ grains in the PANI:Cr 3+ /PVA blend sample are responsible for its high temperature conductivity.

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“…Figures 5(a), (b) illustrate the frequency dependence of the real (M′) and imaginary part (M″) of the nanocomposites. The M′ values initially were almost approaching zero at a lower frequency due to electrode polarization, and getting increased towards higher frequency [34,35]. Meanwhile, M″ shows an asymmetric spectra that represent relaxation frequency of the nanocomposites.…”

Section: Materials Characterizationmentioning

confidence: 98%

The tunable permittivity of multi-walled carbon nanotubes/silver nanoparticles reinforced polyvinyl alcohol (PVA) nanocomposites at low frequency

Yusof

Wong

et al. 2018

Mater. Res. Express

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This paper is about tailoring high permittivity of multi-walled carbon nanotubes/silver nanoparticles (MWNT-AgNP) filled polyvinyl alcohol (PVA) nanocomposites at low frequency. PVA/MWNTAgNP nanocomposites were synthesized via solution-casting technique at low MWNT content with different loading of AgNP. The nanocomposites showed a significant increment in ac conductivity, σ ac , and dielectric permittivity, ε′ by two orders of magnitude as compared to pure PVA. The maximum ε′ value was achieved about 600 at 1.0 wt% of AgNP due to the increased charge carriers density and high interfacial polarization within the nanocomposites. The relaxation frequency was shifted towards a higher value with the increased of AgNP content while the relaxation time was decreased by 40%. Field emission scanning electron microscopy (FESEM) images showed the enhanced distribution of MWNT in the presence of AgNP to provide conductive pathways in the matrix. This was confirmed by energy-dispersive x-ray (EDX) analysis and ultraviolet-visible (UV-vis) spectroscopy. As a result, PVA/MWNT-AgNP nanocomposites have great potential for electrical applications such as cable accessories, high charge-storage capacitor and electromagnetic interference shielding materials.

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Dielectric relaxation in polyaniline–polyvinyl alcohol composites

Cited by 171 publications

References 8 publications

Structure and Physical Properties of NiO/Co3O4 Nanoparticles

Structure and Physical Properties of NiO/Co3O4 Nanoparticles

AC electrical conductivity of Cr-doped polyaniline/poly(vinyl alcohol) blends

The tunable permittivity of multi-walled carbon nanotubes/silver nanoparticles reinforced polyvinyl alcohol (PVA) nanocomposites at low frequency

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