Polaronic hopping conduction in poly(<i>N</i>-methyl pyrrole-pyrrole) copolymer

Singh, R. N.; Narula, Amarjeet K.; Tandon, R. P.; Mansingh, Abhai; Chandra, Subhas

doi:10.1080/13642819708202328

Cited by 16 publications

(17 citation statements)

References 38 publications

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“…However, after this decrease the dielectric constant increases suddenly with increase in temperature. The increase in dielectric constant after the saturation region will be ignored in further discussion since it may be due to the electrode polarization or ionic conduction [15] and does not necessarily represent the true bulk property of the material as has been discussed earlier [11]. The thickness independent dielectric constant of the sample (results not shown) and a decrease of static dielectric constant with increase in temperature clearly indicate the measured values of dielectric constant represent the true bulk phenomenon [11,12] present investigation.…”

Section: Resultsmentioning

confidence: 80%

“…The dielectric parameters were evaluated by measuring equivalent parallel capacitance C p and dissipation factor tan δ or the equivalent resistance R p of the samples. A frequency dependent complex conductivity can arise from interfacial polarization at contacts, grain boundaries or from other inhomogeneities [11] present in the system. The evidence for such effects arising from ohmic and non-ohmic contacts have been discussed earlier [12].…”

Section: Resultsmentioning

confidence: 99%

“…The dielectric parameters are usually represented in terms of dielectric constant [ε (ω)] and dielectric loss [ε (ω)]. In the past decades, especially in the interpretation of the data of amorphous materials [11], it has been customary to represent the data in terms of the dielectric constant ε (ω) and σ (ω). Here σ (ω) is the real part of the conductivity and is related [13,14] to dielectric loss as…”

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

AC Conductivity and Dielectric Relaxation Behavior of Solution Grown Poly (Vinylidene Fluoride) Films

Singh

Sinha²,

Kaur

et al. 2005

Ferroelectrics

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Ac conductivity [σ m (ω)], dielectric constant [ε (ω)] and dielectric loss [ε (ω)] of solution grown poly (vinylidene fluoride) (PVDF) films (thick ∼85-100 µm) have been measured in the temperature range 77-400 K and in the frequency range 100 HZ-10 MHz. A frequency dependent conductivity described by the relation σ (ω) = Aω s , is observed in the low temperature region where s < 1 and is independent of temperature up to 200 K and decreases with increase in temperature. The density of states at the Fermi level [N (E F )] estimated at 77 K and 100 kHz is ∼1.1×10 18 −4.8×10 19 cm −3 eV −1 . The dielectric constant in the low temperature region (<200 K) shows a very weak frequency and temperature dependence. However, in the higher temperature region (>250 K) a strong frequency dispersion of dielectric constant and strong temperature dependence of ac conductivity are observed. Three relaxations; the α c − , the α a − and the β-relaxations, appearing from high temperature side to the low temperature side in the dielectric loss versus temperature spectrum, having activation energy ∼0.232-0.474 eV, ∼0.189-0.226 eV and ∼ 0.052-0.068 eV, respectively have been observed in the present investigation. The activation energies (∼0.02-0.05 eV) of the charge carriers calculated at 77 K indicates the evidence of electronic hopping conduction in the low temperature region.

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Section: Resultsmentioning

confidence: 80%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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AC Conductivity and Dielectric Relaxation Behavior of Solution Grown Poly (Vinylidene Fluoride) Films

Singh

Sinha²,

Kaur

et al. 2005

Ferroelectrics

Self Cite

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“…The real part ε relates to the behaviour of an ideal insulator and characterizes the degree of electric polarizability of the material while the imaginary exponent, ε r , is associated with the electric energy dissipation into heat, due to electrical conduction and polarized charge fluctuation and is responsible for the phase difference between the applied alternating electric field and the polarization (Chong et al 2004). The constant value of the capacitance at high frequency indicates that the imaginary exponent, ε r , is zero at that frequency (Singh et al 1997) and medium permittivity can be calculated from the capacitance directly as ε = C(A/d), where C is the capacitance, A the cross sectional area and d the distance between the electrodes. The dielectric constant measured by ε d = ε / ε 0 , where ε 0 is the permittivity of vacuum (8·854 × 10 −12 farad/m).…”

Section: Measurement Of Dielectric Constants Of Different Polymerizatmentioning

confidence: 99%

“…All the dielectric constants of the polymerization medium were measured at the frequency of 1 MHz where the measured capacitance value becomes constant as shown in figure 1. The constant value of the capacitance indicates that the imaginary component ε r is zero at that frequency (Singh et al 1997) and the dielectric constant or the permittivity of the polymerization medium can be calculated from the relation, ε = C(A/d), where C is the capacitance, A the cross-sectional area and d the distance between the electrodes. Table 1 shows the dielectric constant and relative dielectric constant calculated for polyaniline polymerized at different volume proportions of binary solvent medium of DMF and water.…”

Section: Measurement Of Dielectric Constantmentioning

confidence: 99%

Influence of dielectric constant of polymerization medium on processability and ammonia gas sensing properties of polyaniline

2011

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Polyaniline (PANI) was synthesized by the oxidation of aniline hydrochloride in the presence of ammonium persulphate and hydrochloric acid. The polymerization reaction was carried out in several batches in different solvent media by changing the volume ratio of N,N-dimethyl formamide (DMF) and water as binary solvent mixture. The dielectric constant of the polymerization medium for each batch reaction was determined by measuring the capacitance with change in frequency. The UV spectra of the synthesized polyaniline solutions helped us to optimize the ratio of the binary solvent to get sufficient polymer growth and processability. Thin film of processable polyaniline was then deposited on glass slides coated with polyvinyl alcohol (PVA) crosslinked with maleic anhydride (MA). FTIR and XRD studies of the coated film were also done. AFM studies further helped in the morphological study of the film deposited. Finally, conductivity and ammonia gas-sensing property of the polyaniline film were also studied.

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How to Install TEMPO in Dielectric Polymers—Their Rational Design toward Energy‐Storable Materials

Feng

Suga

Nishide

et al. 2018

Macromol. Rapid Commun.

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Polar groups and the charge‐transport capability play significant roles in the dielectric properties of organic polymers, and thus influence the electric energy density upon application as a capacitor material. Here, the dielectric properties and electric conductivity of a series of polymers containing 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) radicals are investigated. The neat radical polymer poly(TEMPO methacrylate) (PTMA) has a high dielectric constant but poor breakdown strength. Poly(methyl methacrylate) (PMMA) is introduced as an insulating polymer with high resistivity on breakdown, along with molecular design of PTMA. Copolymers of TEMPO methacrylate and methyl methacrylate, P(TMA‐r‐MMA), exhibit high breakdown strengths but low dielectric constants. PMMA blended with TEMPO exhibits the highest electric energy density of 7.4 J cm−3 (that of PTMA is 0.48 J cm−3 as a control), with both a high dielectric constant (≈6.8) and a high breakdown strength (≈500 MV m−1). It benefits from long‐range but not bulk charge transport in the blends, which is different from the bulk charge transport in PTMA and the short‐range charge transport in P(TMA‐r‐MMA). These results indicate that the TEMPO moiety located in the high breakdown matrix leads to a high energy‐storage density in the capacitor.

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Polaronic hopping conduction in poly(N-methyl pyrrole-pyrrole) copolymer

Cited by 16 publications

References 38 publications

AC Conductivity and Dielectric Relaxation Behavior of Solution Grown Poly (Vinylidene Fluoride) Films

AC Conductivity and Dielectric Relaxation Behavior of Solution Grown Poly (Vinylidene Fluoride) Films

Influence of dielectric constant of polymerization medium on processability and ammonia gas sensing properties of polyaniline

How to Install TEMPO in Dielectric Polymers—Their Rational Design toward Energy‐Storable Materials

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