Electrical conductivity relaxation and nuclear magnetic resonance of Li conducting<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Li</mml:mi></mml:mrow><mml:mrow><mml:mn>0.5</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">La</mml:mi></mml:mrow><mml:mrow><mml:mn>0.5</mml:mn></mml:mrow></mm

León, Carlos; Lucı́a, M. L.; Santamarı́a, J.; Paris, M.; Sanz, J.; Várez, A.

doi:10.1103/physrevb.54.184

Cited by 95 publications

(59 citation statements)

References 10 publications

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“…We have performed complex admittance measurements at low temperatures of the crystalline fast ionic conductor Li 3x La 2͞32x TiO 3 . This ionically conducting material is a model system for this purpose since it shows a high ionic conductivity [25][26][27][28], and the highest value ever determined of the constant loss term [18]. We find that the NCL dominates the s 0 ͑v͒ at time scales t , t m and observe a crossover of s 0 ͑v͒ to the sublinear frequency dependence of Eq.…”

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confidence: 90%

Origin of Constant Loss in Ionic Conductors

et al. 2001

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We have analyzed the constant loss contribution to the ac conductivity in the frequency range 10 Hz -1 MHz and temperatures down to 8 K, for two Li ionic conductors, one crystalline (Li 0.18 La 0.61 TiO 3 ) and the other glassy (61SiO 2 ? 35Li 2 O ? 3Al 2 O 3 ? P 2 O 5 ). As temperature is increased a crossover is observed from a nearly constant loss to a fractional power law frequency dependence of the ac conductivity. At any fixed frequency v, this crossover occurs at a temperature T such that v ഠ n 0 exp͑2E m ͞k B T͒, where n 0 is the attempt frequency and E m is identified with the barrier for Li 1 ions to leave their wells. DOI: 10.1103/PhysRevLett.86.1279 Much effort has been devoted during the last few decades to understand the dynamics of ionic transport in ionically conducting materials. In spite of the advances made, there is still no general agreement on interpretation of the experimental data [1][2][3][4][5][6][7][8][9][10][11]. Most research activity in this field has focused on the origin and properties of the long-range ion motion, and electrical relaxation is the most commonly used experimental tool to access the ion dynamics. The frequency dependence of the ionic conductivity can be usually well described by using Jonscher's expression [12]where s 0 is the dc conductivity, v p is a characteristic relaxation frequency, and n is a fractional exponent. Both s 0 and v p are thermally activated with about the same activation energy, indicating that the dispersive conductivity, s ‫ء‬ ͑v͒, originates from migration of ions. However, there is another ubiquitous contribution to dispersive conductivity that has received much less attention so far. This contribution consists of a nearly frequency independent dielectric loss,´0 0 ͑v͒ ഠ A, which corresponds to an almost linear frequency dependent term of the form s 0 ͑v͒ v´0 0 ͑v͒ ഠ Av in the real part of the complex conductivity. At sufficiently low temperature or high frequencies, the Av term dominates over the power law dependence of exponent n. The existence of this nearly constant loss (NCL) was suggested more than 20 years ago and subsequently verified [13,14]. Since then, few investigations of its properties have been made [15][16][17] and low temperature data with its dominant contribution are still scarce.Although, ultimately, mobile ions seem to be responsible also for the NCL, the experimental facts including its dependence on temperature and the effect of mixed alkalis point to a different origin than ionic hopping [18]. Experimentally, A is not thermally activated and has temperature dependence much milder than s 0 or v p [18][19][20]. Partial replacement by alkali ions of a different kind has the effect of reducing the NCL [3,18,21,22], but the reduction in A is much smaller than the decrease in s 0 due to the well-known mixed alkali effect [3]. From these facts, it has been very recently proposed [18] that local vibrational relaxation reflected in the mean-square displacement of ions could be the origin of the constant loss in ionic conductors...

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Origin of Constant Loss in Ionic Conductors

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“…* is a temperature activated relaxation time and 0Ͻ␤Ͻ1. The stretched exponential parameter ␤ describes the slowing down of the relaxation process as a result of correlated ion hopping, [15][16][17] such that one expects ␤ to be close to zero for strongly correlated ion motion and one for random Debyelike hops. An exponent ␤ϭ0.45Ϯ0.02 is obtained from the fits over the whole temperature range.…”

Section: ͑1͒mentioning

confidence: 99%

Electrical conductivity relaxation in thin-film yttria-stabilized zirconia

Rivera

Santamarı́a

León

2001

Applied Physics Letters

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We report on complex admittance measurements on ZrO2:Y2O3 (YSZ) thin films in the parallel plate geometry. Highly textured YSZ thin films, grown by rf sputtering, allow measuring complex admittance free of the effect of charge blocking at grain boundaries. We have examined low-temperature (close to room temperature) regime dominated by association of oxygen vacancies. Complex admittance analyzed in terms of the modulus formalism supplies information on correlation effects in ion motion and allows obtaining an association energy for the oxygen vacancies of 0.45 eV, in agreement with previous theoretical calculations.

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“…The choice of this ionically conducting material is based on its high ionic conductivity, [27][28][29][30][31] and because it shows the highest value ever determined of the nearly constant loss, 3 to our knowledge. By analyzing isothermal ac conductivity data, we extend the temperature range of the crossover region found in Ref.…”

Section: ͑2͒mentioning

confidence: 99%

Crossover from ionic hopping to nearly constant loss in the fast ionic conductorLi0.18La0.61TiO
Rivera-Calzada
¹
,
Yebra
²
,
Sanz
³

et al. 2002
Phys. Rev. B
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Electrical conductivity measurements of the fast ionic conductor Li 0.18 La 0.61 TiO 3 have been conducted at temperatures ranging from 8 to 300 K and frequencies between 20 Hz and 5 MHz. A detailed analysis of the ac conductivity shows the existence of a crossover between two different regimes. At high temperatures and/or low frequencies correlated ion hopping is responsible for a power-law frequency dependent and thermally activated ac conductivity. On the other hand, at sufficiently low temperatures and/or high frequencies, the ions do not have enough thermal energy or time to hop between neighboring sites, and remain caged. The ac conductivity is then characterized by a linear frequency dependence ͑i.e., the equivalent of a nearly constant loss͒ and by a weak exponential temperature dependence of the form exp(T/T 0 ). A crossover between the two regimes is found, which is thermally activated with an activation energy Eϭ0.17 eV, significantly lower than that observed for the dc conductivity, E ϭ0.4 eV. From this result, it is shown that the so-called ''augmented Jonscher expression'' fails to describe the ac conductivity in the whole frequency and temperature ranges. All these findings suggest that the nearly constant loss originates from electrical loss occurring during the time regime while the ion is still confined in the potential-energy minimum. Further, it is proposed that the loss mechanism involves some type of process where the potential-energy minimum relaxes in time on a time scale much shorter than the ionic hopping time scale. At longer times, as soon as the ion has significant probability of being thermally activated out of the potential well, the nearly constant loss terminates and correlated ion hopping becomes the only contribution to the ac conductivity.

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Electrical conductivity relaxation and nuclear magnetic resonance of Li conductingLi0.5La0.5

Cited by 95 publications

References 10 publications

Origin of Constant Loss in Ionic Conductors

Origin of Constant Loss in Ionic Conductors

Electrical conductivity relaxation in thin-film yttria-stabilized zirconia

Crossover from ionic hopping to nearly constant loss in the fast ionic conductorLi0.18La0.61TiO
Rivera-Calzada
¹
,
Yebra
²
,
Sanz
³

et al. 2002
Phys. Rev. B
Self Cite
39
3
22
0
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Electrical conductivity relaxation and nuclear magnetic resonance of Li conductingLi0.5La0.5

Cited by 95 publications

References 10 publications

Origin of Constant Loss in Ionic Conductors

Origin of Constant Loss in Ionic Conductors

Electrical conductivity relaxation in thin-film yttria-stabilized zirconia

Crossover from ionic hopping to nearly constant loss in the fast ionic conductorLi0.18La0.61TiORivera-Calzada1, Yebra2, Sanz3 et al. 2002Phys. Rev. BSelf Cite393220View full textAdd to dashboardCite

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Crossover from ionic hopping to nearly constant loss in the fast ionic conductorLi0.18La0.61TiO
Rivera-Calzada
¹
,
Yebra
²
,
Sanz
³

et al. 2002
Phys. Rev. B
Self Cite
39
3
22
0
View full text Add to dashboard Cite