Stimulated-Echo NMR Spectroscopy of 9Be and 7Li in Solids: Method and Application to Ion Conductors

Qi, Fei; Jörg, T.; Böhmer, Roland

doi:10.1006/snmr.2002.0073

Cited by 70 publications

(89 citation statements)

References 36 publications

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“…The decay of the echo signal with respect to t m is then interpreted to be due to the motion of the spin carrying ions that come along with changes of the dominating quadrupolar precession frequency. However, this simple interpretation is only possible if frequency changes of another origin can be neglected, 32,40 e.g., if dipolar correlations are kept small by sufficiently short evolution times. In experimental practice, further effects, such as spin relaxation and spin diffusion, can lead to a premature decay of the echo and have to be taken into account.…”

Section: B Stimulated Echoesmentioning

confidence: 99%

“…32 For x = 0.5, we employed stimulated-echo experiments with evolution times ranging from 15 to 410 μs at 370 K. For t p < 50 μs we find almost constant τ c values and a slight decrease for larger t p (not shown). The latter arises from the growing dipolar contribution, 40 thereby hampering a simple interpretation of the decay time.…”

Section: Dynamics Probed By Two-time Correlation Functionsmentioning

confidence: 99%

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NMR and conductivity studies of the mixed glass former effect in lithium borophosphate glasses

Storek

Böhmer

Martin

et al. 2012

The Journal of Chemical Physics

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Alkali ion charge transport has been studied in a series of mixed glass former lithium borophosphate glasses of composition 0.33Li 2 O + 0.67[xB 2 O 3 + (1 -x)P 2 O 5 ]. The entire concentration range, 0.0 ≤ x ≤ 1.0, from pure glassy Li 2 P 4 O 11 to pure glassy Li 2 B 4 O 7 has been examined while keeping the molar fraction of Li 2 O constant. Electrical conductivity measurements and nuclear magnetic resonance techniques such as spin relaxometry, line shape analysis, and stimulated-echo spectroscopy were used to examine the temperature and frequency dependence of the Li + ion motion over wide ranges of time scale and temperature. By accurately determining motional time scales and activation energies over the entire composition range the ion dynamics and the charge transport are found to be fastest if the borate and the phosphate fractions are similar. The nonlinear variation of the charge conduction, the most notable feature of the mixed glass former effect, is discussed in terms of the composition dependence of network former units which determine the local glass structure. Electrical conductivity measurements and nuclear magnetic resonance techniques such as spin relaxometry, line shape analysis, and stimulated-echo spectroscopy were used to examine the temperature and frequency dependence of the Li + ion motion over wide ranges of time scale and temperature. By accurately determining motional time scales and activation energies over the entire composition range the ion dynamics and the charge transport are found to be fastest if the borate and the phosphate fractions are similar. The nonlinear variation of the charge conduction, the most notable feature of the mixed glass former effect, is discussed in terms of the composition dependence of network former units which determine the local glass structure.

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Section: B Stimulated Echoesmentioning

confidence: 99%

Section: Dynamics Probed By Two-time Correlation Functionsmentioning

confidence: 99%

NMR and conductivity studies of the mixed glass former effect in lithium borophosphate glasses

Storek

Böhmer

Martin

et al. 2012

The Journal of Chemical Physics

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“…First, Tang et al 20,56,57 recorded 9 Be NMR spin-alignment echoes to study ultraslow ionic motions in a metallic beryllium containing glass in order to reveal the prevailing diffusion mechanism in this material. The method was then used by Böhmer and co-workers 58,59 to investigate ultraslow Li motions in crystalline Li 3 68 It is worth mentioning in this context that 109 Ag stimulated echo NMR two-and four-time correlation functions were recorded recently to investigate silver dynamics in glasses of the compositions ͑AgI͒ x -͑AgPO 3 ͒ ͑1−x͒ , [69][70][71][72] 73 as well as in several other Ag compounds. 74,75 In contrast to spin-1 and spin-3 / 2 nuclei, in the case of the nonquadrupolar 109 Ag nucleus with I =1/ 2 chemical shift interactions are used to differentiate between the ions.…”

Section: Accessible Time Scales By Nmrmentioning

confidence: 99%

Li jump process inh−Li0.7TiS2studied by two-time
Wilkening
¹
,
Heitjans
²

2008
Phys. Rev. B
98
8
158
1
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7 Li spin-alignment NMR is used to trace ultraslow diffusion of Li + in the layered Li conductor Li x TiS 2 ͑x = 0.7͒. Two-time correlation functions were recorded for fixed evolution times as a function of mixing time at temperatures within the 7 Li rigid-lattice regime. The corresponding decay rates were identified as Li jump rates −1 ranging from 10 −1 to 10 3 s −1 between temperatures T = 148 K and 213 K. The jump rates obtained directly from spin-alignment echo NMR and those from diffusion induced maxima of spin-lattice relaxation peaks, monitored in the laboratory as well as in the rotating frame, are consistent with each other and follow an Arrhenius law with an activation energy of 0.41͑1͒ eV and a preexponential factor of 6.3͑1͒ ϫ 10 12 s −1 . Altogether, a solitary Li diffusion process was found between 148 and 510 K. Li diffusion was investigated in a dynamic range of about 10 orders of magnitude, i.e., 0.1ഛ −1 ഛ 7.8ϫ 10 8 s −1 . Additionally, the analysis of final-state echo amplitudes of the two-time correlation functions revealed information about the Li diffusion pathway in Li 0.7 TiS 2 . Obviously, a two-site jump process is present, i.e., besides the regularly occupied octahedral sites also the vacant tetrahedral ones within the van der Waals gap are involved in the overall two-dimensional diffusion process.

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“…Advantageous over already well-established Li NMR methods [15][16][17][18][19] is the use of 7 Li stimulated echo, or more precisely, spin-alignment echo ͑SAE͒ NMR which has so far been applied mainly to crystalline Li conductors. 17,[20][21][22][23][24][25][26][27][28][29][30][31][32] Similar to modern twodimensional 6 Li and 7 Li exchange NMR spectroscopy, 33-38 7 Li SAE NMR is sensitive to extremely slow cation exchange processes and gives access to diffusion parameters from a microscopic point of view. Thus, it is possible to record single-particle motional correlation functions, 39 from which the atomic jump rate can be directly obtained, i.e., without the help of a diffusion model.…”

Section: Introductionmentioning

confidence: 99%

Atomic-scale measurement of ultraslow Li motions in glassyLiAlSi2O6by two-timeL6
Wilkening
¹
,
Kuhn
²
,
Heitjans
³

2008
Phys. Rev. B
59
4
50
0
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6 Li spin-alignment echo ͑SAE͒ nuclear-magnetic-resonance ͑NMR͒ spectroscopy is used to monitor singleparticle two-time correlation functions in LiAlSi 2 O 6 glass. The method, here applied in the temperature range from 300 to 400 K, is sensitive to ultraslow Li hopping processes with rates ͑1 / SAE ͒ down to 10 jumps/s. The use of a sample with natural 6 Li abundance allowed the measurement of pure NMR spin-alignment echoes which are damped with increasing mixing time exclusively by slow Li jumps, i.e., free of influences arising from, e.g., interfering spin-diffusion effects. The considerably stretched correlation functions reveal the presence of a broad distribution of jump rates. The results are comprehensively compared with those recently obtained from both 7 Li SAE and 7 Li spin-lattice relaxation NMR as well as from dc conductivity measurements. Interestingly, the activation energy of the latter, which are sensitive to long-range Li transport parameters, is in good agreement with that microscopically probed by 6 Li SAE NMR, here.

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Stimulated-Echo NMR Spectroscopy of 9Be and 7Li in Solids: Method and Application to Ion Conductors

Cited by 70 publications

References 36 publications

NMR and conductivity studies of the mixed glass former effect in lithium borophosphate glasses

NMR and conductivity studies of the mixed glass former effect in lithium borophosphate glasses

Li jump process inh−Li0.7TiS2studied by two-time
Wilkening
¹
,
Heitjans
²

2008
Phys. Rev. B
98
8
158
1
View full text Add to dashboard Cite

Atomic-scale measurement of ultraslow Li motions in glassyLiAlSi2O6by two-timeL6
Wilkening
¹
,
Kuhn
²
,
Heitjans
³

2008
Phys. Rev. B
59
4
50
0
View full text Add to dashboard Cite

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Stimulated-Echo NMR Spectroscopy of 9Be and 7Li in Solids: Method and Application to Ion Conductors

Cited by 70 publications

References 36 publications

NMR and conductivity studies of the mixed glass former effect in lithium borophosphate glasses

NMR and conductivity studies of the mixed glass former effect in lithium borophosphate glasses

Li jump process inh−Li0.7TiS2studied by two-timeWilkening1, Heitjans2 2008Phys. Rev. B9881581View full textAdd to dashboardCite

Atomic-scale measurement of ultraslow Li motions in glassyLiAlSi2O6by two-timeL6Wilkening1, Kuhn2, Heitjans3 2008Phys. Rev. B594500View full textAdd to dashboardCite

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Li jump process inh−Li0.7TiS2studied by two-time
Wilkening
¹
,
Heitjans
²

2008
Phys. Rev. B
98
8
158
1
View full text Add to dashboard Cite

Atomic-scale measurement of ultraslow Li motions in glassyLiAlSi2O6by two-timeL6
Wilkening
¹
,
Kuhn
²
,
Heitjans
³

2008
Phys. Rev. B
59
4
50
0
View full text Add to dashboard Cite