Effect of zirconia doping on the electrical behavior of yttria

The ac electrical behavior of yttria doped with a zirconia concentration ranging from 0.15 to 20 mole % is investigated in the temperature range of 800 to 1300 °C. The ac electrical data, obtained in the range from 5 Hz to 13 MHz, indicated two distinct relaxations when analyzed in the impedance plane. These relaxations are attributed to lumped grains and trapping within grain boundaries, including possible electrode/sample effects. The admittance plane analysis revealed a semicircular relaxation in the low-frequency region, indicating identical response to that of the low-frequency relaxation of the impedance plane. The incorporation of zirconia into yttria is found to lower the activation energy of conduction in the grains and enhance ionic contribution to the overall electrical conduction. The PO2 studies and transference number measurements near atmospheric region indicate that p-type conduction dominates for the lightly doped yttria. An ionic contribution to the conduction processes becomes significant in heavily doped samples at/near atmospheric PO2.

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Investigating the dielectric properties and low-frequency relaxation process of TlGaSe2 crystals

Modern Physics Letters B ◽

10.1142/s0217984917501342 ◽

2017 ◽

Vol 31 (12) ◽

pp. 1750134 ◽

Cited By ~ 1

Author(s):

Oktay Samadov ◽

Oktay Alakbarov ◽

Arzu Najafov ◽

Samir Samadov ◽

Nizami Mehdiyev ◽

...

Keyword(s):

Electrical Conductivity ◽

Relaxation Time ◽

Constant Electric Field ◽

Low Frequency ◽

Constant Field ◽

Impedance Spectra ◽

Ionic Contribution ◽

Frequency Relaxation ◽

Average Relaxation Time ◽

Diagram Analysis

The dielectric and impedance spectra of TlGaSe2 crystals have been studied at temperatures in the 100–500 K range in the alternating current (AC [Formula: see text]1 V). It has been shown that the conductivity of TlGaSe2 crystals is mainly an ionic characteristic at temperatures above 400 K. The well-defined peak at the frequency dependence of the imaginary part of impedance [Formula: see text] is observed in the 215–500 K temperature range. In a constant field, there occurs a significant decrease in electrical conductivity [Formula: see text] in due course. The ionic contribution to conductivity (76% at [Formula: see text]) has been estimated from a kinetic change in electrical conductivity [Formula: see text] under the influence of a constant electric field. The diagram analysis in a complex plane [Formula: see text] has been conducted by applying the method of an equivalent circuit of the substation. It has been determined that the average relaxation time of the electric module of the sample is [Formula: see text].

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Low-Frequency Relaxation Phenomena in α-LiIO3: The Nature and Role of Defects

Journal of Solid State Chemistry ◽

10.1006/jssc.2002.9683 ◽

2002 ◽

Vol 168 (1) ◽

pp. 76-84 ◽

Cited By ~ 10

Author(s):

Y. Mugnier ◽

C. Galez ◽

J.M. Crettez ◽

P. Bourson ◽

C. Opagiste ◽

...

Keyword(s):

Low Frequency ◽

Relaxation Phenomena ◽

Frequency Relaxation

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Dynamics of Ferroelectric and Nematic Liquid Crystals Confined in Porous Matrices

MRS Proceedings ◽

10.1557/proc-366-445 ◽

1994 ◽

Vol 366 ◽

Cited By ~ 1

Author(s):

Fouad M. Aliev

Keyword(s):

Liquid Crystals ◽

Heterogeneous Media ◽

Volume Fraction ◽

Low Frequency ◽

Pore Wall ◽

Polar Molecules ◽

Average Pore ◽

Surface Polarization ◽

The Difference ◽

Frequency Relaxation

ABSTRACTWe performed dielectric spectroscopy measurements to study dynamics of collective modes of ferroelectric (FLC) and molecular motion of nematic (NLC) liquid crystals with polar molecules confined in silica macroporous and microporous glasses with average pore sizes of 1000 Å (volume fraction of pores 40%) and 100 Å (27%) respectively. For FLC the Goldstone and the soft modes are found in macropores. The rotational viscosity associated with the soft mode is about 10 times higher in pores than in the bulk. These modes are not detected in micropores although low frequency relaxation is present. The last one probably is not connected with the nature of liquid crystal but is associated with surface polarization effects typical for two component heterogeneous media. The difference between the dynamics of orientational motion of the polar molecules of NLC in confined geometries and in the bulk is qualitatively determined by the total energy Fs of the interaction between molecules and the surface of the pore wall, which is found Fs ≈ 102erg/cm2.

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