Impedance and dielectric spectroscopy revisited: Distinguishing localized relaxation from long-range conductivity

Gerhardt, Rosario A.

doi:10.1016/0022-3697(94)90575-4

Cited by 813 publications

(418 citation statements)

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“…With increase in temperature, the value of Z merges in the high-frequency region. This may be the temperature-dependent relaxation phenomenon in which the hopping of charge carriers and polarons is dominating in the polycrystalline material [21,22].…”

Section: Resultsmentioning

confidence: 99%

Electrical properties of bulk and nano Li2TiO3 ceramics: A comparative study

et al. 2014

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Nanocrystalline and bulk Li 2 TiO 3 having monoclinic structure were prepared by mechanical alloying as well as conventional ceramic route. Complex impedance analysis in the frequency range of 100 Hz-1 MHz over a wide range of temperature (50-500 ℃) indicates the presence of grain boundary effect along with the bulk contribution. The frequency-dependent conductivity plots exhibit power law dependence, suggesting three types of conduction in the material: low-frequency (100 Hz-1 kHz) conductivity showing long-range translational motion of electrons (frequency independent), mid-frequency (1-10 kHz) conductivity showing short-range hopping of charge carriers and high-frequency (10 kHz-1 MHz) conductivity showing conduction due to localized orientation of hopping mechanism. The electrical conductivity measurement of nanocrystalline and bulk Li 2 TiO 3 with temperature shows the negative temperature coefficient of resistance (NTCR) behavior. The activation energy (0.77 eV for nano sample and 0.88 eV for bulk sample) study shows the conduction mechanism in both samples. The low activation energies of the samples suggest the presence of singly ionized oxygen vacancies in the conduction process.

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Section: Resultsmentioning

confidence: 99%

Electrical properties of bulk and nano Li2TiO3 ceramics: A comparative study

et al. 2014

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“…The fabrication procedure followed closely the method of Grimes and coworkers 10,12 . A 2 cm x 1.5 cm titanium foil (99.7%; Sigma-Aldrich) with a thickness of 250 µm was immersed into an etching solution containing 0.334 g of NH 4 F (Sigma-Aldrich) dissolved into 2.2 ml of DI water and 97.47 ml of ethylene glycol (anhydrous, 99.8%; Sigma-Aldrich).…”

Section: Methodsmentioning

confidence: 99%

Synthesis and variable temperature electrical conductivity studies of highly ordered TiO2 nanotubes

Asmatulu

Karthikeyan²,

Bell

et al. 2009

J Mater Sci

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Rafts of aligned, high aspect ratio TiO 2 nanotubes were fabricated by an electrochemical anodization method and their axial electrical conductivities were determined over the temperature range 225-400 °C. Length, outer diameter and wall thickness of the nanotubes were approximately 60-80 µm, 160 nm and 30 nm, respectively. Transmission electron microscopy studies confirmed that the TiO 2 nanotubes were initially amorphous, and became polycrystalline anatase after heat treatment at temperatures as low as 250 °C in air. The activation energy for conductivity over the temperature range 250 -350 °C was found to be 0.87 eV. The conductivity values are comparable to those of nanocrystalline and nanoporous anatase thin films reported in literature.

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“…The relaxation peak observed for the PMC for f con > f c in lower frequency region is due to the development of long-range dc conduction, which is attributed to the conductivity relaxation/MWS relaxation. [22][23][24][25] Figure 4(c) shows the dispersion of ac conductivity ( ac ) with frequency for all the samples corresponding to f con < f c with the dc conductivity ( dc ) part becomes zero, whose detailed analysis can be found from earlier literature. 8 The value of low frequency ac is less than 10 À7 S/m for the samples f con ¼ 0:20 and 0.25, while it increases by one order for the f con ¼ f c ¼ 0:27 sample and it reaches $ 10 À6 S/m and after that it increases by orders reaching the value $ 10 À4 -10 À5 S/m for f con ¼ 0:28 to 0.30.…”

Section: Impedance and Conductivity Spectroscopymentioning

confidence: 99%

Evidence of a third kind of Johnscher’s like universal dielectric response

Panda

2018

J. Adv. Dielect.

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Polymer/metal composites (PMC) comprising of polyvinylidene fluoride/nanocrystalline nickel with varying volume fractions of nickel (f con ) prepared under cold press show an insulator to metal transition (IMT) at percolation threshold (f c ¼ f con ¼ 0:27). The two kinds of generalized Johnscher's universal dielectric response (UDR) laws on both sides of IMT hold good, while for the percolative sample, none of the two laws hold good. Neither the concept of dipolar relaxation nor anomalous low frequency dispersion stands valid for f c ¼ 0:27, while a completely different, neutral and competing electrical behavior is observed over the entire range of frequencies. The emerged third kind of Johnscher's like UDR for f c is observed and the relaxation law has been formulated as the ratio of imaginary and real parts of dielectric constant remains constant over the entire range of frequency starting from dc to any higher frequency. The value of the constant is attributed to depend on the PMC, the dielectric constant of the polymer, the differences of conductivity and fractions of the components of the PMC and also on their connectivity arising due to the difference of their process conditions. The emerged unique dielectric relaxation consists of multiple relaxations arising due to the combination of other relaxations (arising due to the two different types of species) present in the sample, f con ¼ 0:27. This novel material may be suitable for certain specific applications in electrical and electronics engineering.

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Impedance and dielectric spectroscopy revisited: Distinguishing localized relaxation from long-range conductivity

Cited by 813 publications

References 50 publications

Electrical properties of bulk and nano Li2TiO3 ceramics: A comparative study

Electrical properties of bulk and nano Li2TiO3 ceramics: A comparative study

Synthesis and variable temperature electrical conductivity studies of highly ordered TiO2 nanotubes

Evidence of a third kind of Johnscher’s like universal dielectric response

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