A novel cross-linked polyimide film: synthesis and dielectric properties

Deligöz, Hüseyin; Özgümüş, Saadet; Yalçınyuva, Tuncer; Yıldırım, Sinem; Deǧer, D.; Ulutaş, Kemal Türker

doi:10.1016/j.polymer.2005.02.097

Cited by 86 publications

(55 citation statements)

References 22 publications

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“…It attains to almost a constant value which shows the influences of frequency and temperature on the conduction mechanism are relatively insignificant at higher frequencies (>10 2 Hz). The variation of relative dielectric constant with frequency reveals the existence of material electrode interface polarization mechanisms, which emerges at lower frequency with a sharp decrease [49]. Additionally, the dielectric constant depends on the rate of polarization in a material orients itself simultaneously with the fluctuations of an alternating electric field.…”

Section: Temperature and Frequency Dependencies Of Dielectric Permittmentioning

confidence: 98%

Synthesis and magneto-electrical properties of MFe2O4 (Co, Zn) nanoparticles by oleylamine route

Kurtan

Erdemi

Baykal

et al. 2016

Ceramics International

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Section: Temperature and Frequency Dependencies Of Dielectric Permittmentioning

confidence: 98%

Synthesis and magneto-electrical properties of MFe2O4 (Co, Zn) nanoparticles by oleylamine route

Kurtan

Erdemi

Baykal

et al. 2016

Ceramics International

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“…where ω is the angular frequency, n is the frequency exponent and A is a temperature independent constant [35,36]. Frequency exponent (n) values were calculated from the slopes of log-log graph and the figures are shown in Fig.…”

Section: Conductivity and Permitivity Measurementsmentioning

confidence: 99%

Triethylene Glycol Stabilized CoFe2O4 Nanoparticles

Baykal

Deligöz

Sözeri

et al. 2012

J Supercond Nov Magn

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We report on the synthesis and detailed composition, thermal, micro-structural, ac-dc conductivity performance and dielectric permittivity characterization of triethylene glycol (TREG) stabilized CoFe 2 O 4 nanoparticles synthesized by polyol method. XRD analysis confirmed the inorganic phase as CoFe 2 O 4 with high phase purity. Microstructure analysis with TEM revealed well separated, spherical nanoparticles in the order of 6 nm, which is also confirmed by X-ray line profile fitting. FT-IR analysis confirms that TREG is successfully coated on the surface of nanoparticles. Overall conductivity of nanocomposite is approximately two magnitudes lower than that of TREG with increase in temperature. The ac conductivity showed a temperature dependent behavior at low frequencies and temperature independent behavior at high frequencies which is an indication of ionic conductivity. The dc conductivity of the nanocomposites and pure TREG are found to obey the Ar-A. Baykal ( ) · Z. Durmus rhenius plot with dc activation energies of 0.258 eV and 0.132 eV, respectively. Analysis of dielectric permittivity functions suggests that ionic and polymer segmental motions are strongly coupled in the nanocomposite. TREG stabilized CoFe 2 O 4 nanoparticles has lower ε and ε than that of pure TREG due to the doping of cobalt. As the temperature increases, the frequency at which (ε ) reaches a maximum shifted towards higher frequencies. On the other hand, the activation energy of TREG for relaxation process was found to be 0.952 eV which indicates the predominance of electronic conduction due to the chemical nature of TREG. Contrarily, no maximum peak of tan δ was observed for the nanocomposite due to the being out of temperature and frequency range applied in the study.

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“…At high frequencies, a.c. conductivity of each product varied with the same way but independent of temperature. In other word, a.c. conductivity over a certain frequency (100 kHz for nanocomposite and 10 kHz for pristine PPyAA) obeyed the rule of the temperature independent expression for several low mobility polymers and even for crystalline materials, non-crystalline and liquid semiconductors; a.c. (ω) = Aω n (2) where ω is the angular frequency, n is the frequency exponent and A is a temperature independent constant [51,52]. Frequency exponent (n) values were calculated from the slopes of log-log graph and the figures are shown in Fig.…”

Section: Ac Conductivitymentioning

confidence: 99%

“…Furthermore, the mobility of the charge carriers increases by increasing the temperature because of the increase in thermal energy [13]. On the other hand, it is known from literature that the addition of nanoparticles alters the molecular dynamics of the matrix polymer at low temperatures [52]. This effect is due to the modified interactions at the interfaces between particles and the matrix.…”

Section: DC Conductivitymentioning

confidence: 99%