NMR relaxation study of ion dynamics in nanocrystalline and polycrystalline LiNbO3

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OriginalspracheEnglisch
Seiten (von - bis)7303-7306
Seitenumfang4
FachzeitschriftJournal of Physical Chemistry B
Jahrgang102
Ausgabenummer38
PublikationsstatusVeröffentlicht - 17 Sept. 1998

Abstract

Nanocrystalline (n) LiNbO3 was prepared by high-energy ball milling from the polycrystalline (p) material. Grain sizes were determined by XRD measurements and TEM images; thermal stability ranges of the samples were examined by DTA. NMR investigations of the diffusion-induced 7Li spin-lattice relaxation (SLR) rate T1-1 of n-LiNbO3 in the temperature range from T = 140 to 460 K at frequencies between ν = 24 and 78 MHz revealed a reduced activation energy on the low-temperature side of the typical peak in a log T1-1 vs T-1 plot in comparison with results obtained from experiments performed on the p-material between 300 and 1400 K. Corresponding measurements of the SLR rate in the rotating reference frame yielded an asymmetric peak in the case of p-LiNbO3, in contradiction to standard BPP theory, whereas in H-LiNbO3 only a weakly temperature-dependent relaxation rate background was observed. Furthermore, neither in n-nor in p-LiNbO3 BPP-type frequency dependencies of the SLR rate, i.e., T1-1 ∝ ν with β = 2, were found. The determined values ranging from β = 1.1 to 1.5 are ascribed to the influence of structural disorder and Coulomb interaction on the diffusive motion.

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NMR relaxation study of ion dynamics in nanocrystalline and polycrystalline LiNbO3. / Bork, D.; Heitjans, P.
in: Journal of Physical Chemistry B, Jahrgang 102, Nr. 38, 17.09.1998, S. 7303-7306.

Publikation: Beitrag in FachzeitschriftArtikelForschungPeer-Review

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title = "NMR relaxation study of ion dynamics in nanocrystalline and polycrystalline LiNbO3",
abstract = "Nanocrystalline (n) LiNbO3 was prepared by high-energy ball milling from the polycrystalline (p) material. Grain sizes were determined by XRD measurements and TEM images; thermal stability ranges of the samples were examined by DTA. NMR investigations of the diffusion-induced 7Li spin-lattice relaxation (SLR) rate T1-1 of n-LiNbO3 in the temperature range from T = 140 to 460 K at frequencies between ν = 24 and 78 MHz revealed a reduced activation energy on the low-temperature side of the typical peak in a log T1-1 vs T-1 plot in comparison with results obtained from experiments performed on the p-material between 300 and 1400 K. Corresponding measurements of the SLR rate in the rotating reference frame yielded an asymmetric peak in the case of p-LiNbO3, in contradiction to standard BPP theory, whereas in H-LiNbO3 only a weakly temperature-dependent relaxation rate background was observed. Furthermore, neither in n-nor in p-LiNbO3 BPP-type frequency dependencies of the SLR rate, i.e., T1-1 ∝ ν-β with β = 2, were found. The determined values ranging from β = 1.1 to 1.5 are ascribed to the influence of structural disorder and Coulomb interaction on the diffusive motion.",
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AU - Bork, D.

AU - Heitjans, P.

PY - 1998/9/17

Y1 - 1998/9/17

N2 - Nanocrystalline (n) LiNbO3 was prepared by high-energy ball milling from the polycrystalline (p) material. Grain sizes were determined by XRD measurements and TEM images; thermal stability ranges of the samples were examined by DTA. NMR investigations of the diffusion-induced 7Li spin-lattice relaxation (SLR) rate T1-1 of n-LiNbO3 in the temperature range from T = 140 to 460 K at frequencies between ν = 24 and 78 MHz revealed a reduced activation energy on the low-temperature side of the typical peak in a log T1-1 vs T-1 plot in comparison with results obtained from experiments performed on the p-material between 300 and 1400 K. Corresponding measurements of the SLR rate in the rotating reference frame yielded an asymmetric peak in the case of p-LiNbO3, in contradiction to standard BPP theory, whereas in H-LiNbO3 only a weakly temperature-dependent relaxation rate background was observed. Furthermore, neither in n-nor in p-LiNbO3 BPP-type frequency dependencies of the SLR rate, i.e., T1-1 ∝ ν-β with β = 2, were found. The determined values ranging from β = 1.1 to 1.5 are ascribed to the influence of structural disorder and Coulomb interaction on the diffusive motion.

AB - Nanocrystalline (n) LiNbO3 was prepared by high-energy ball milling from the polycrystalline (p) material. Grain sizes were determined by XRD measurements and TEM images; thermal stability ranges of the samples were examined by DTA. NMR investigations of the diffusion-induced 7Li spin-lattice relaxation (SLR) rate T1-1 of n-LiNbO3 in the temperature range from T = 140 to 460 K at frequencies between ν = 24 and 78 MHz revealed a reduced activation energy on the low-temperature side of the typical peak in a log T1-1 vs T-1 plot in comparison with results obtained from experiments performed on the p-material between 300 and 1400 K. Corresponding measurements of the SLR rate in the rotating reference frame yielded an asymmetric peak in the case of p-LiNbO3, in contradiction to standard BPP theory, whereas in H-LiNbO3 only a weakly temperature-dependent relaxation rate background was observed. Furthermore, neither in n-nor in p-LiNbO3 BPP-type frequency dependencies of the SLR rate, i.e., T1-1 ∝ ν-β with β = 2, were found. The determined values ranging from β = 1.1 to 1.5 are ascribed to the influence of structural disorder and Coulomb interaction on the diffusive motion.

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