Dresden 2003 – scientific programme

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DF: Dielektrische Festkörper

DF 7: Poster

DF 7.19: Poster

Wednesday, March 26, 2003, 14:30–18:00, P2a

Impedance spectroscopy study of Li ion dynamics in microcrystalline, nanocrystalline and amorphous LiNbO₃ — •Muayad Masoud and Paul Heitjans — Institut für Physikalische Chemie und Elektrochemie, Universität Hannover, Callinstraße 3–3a, D-30167, Hannover.

Complementary to recent NMR work by our group [1, 2], we investigated the Li ion diffusivity in microcrystalline, nanocrystalline and amorphous LiNbO₃ by impedance spectroscopy. Nanocrystalline LiNbO₃ was prepared with various average grain sizes in the range from 15 nm to 100 nm by high-energy ball milling, and the amorphous form was prepared by a sol-gel route.

Measurements were performed in the frequency range from ω/2π= 5 Hz to 13 MHz under oxygen atmosphere and at temperatures ranging from 300 K to 450 K for the nanocrystalline and amorphous samples to prevent grain growth and up to 670 K for the microcrystalline material. Ionic conductivity was found to increase by going from the microcrystalline via the corresponding nanocrystalline to the amorphous form. In all cases the real part of the conductivity follows the power law: σ′ = σ_dc + Aω^s, with 0<s<1. Impedance data are also analyzed in the complex plane plot with ω as implicit parameter.

[1] M. Wilkening, D. Bork, S. Indris and P. Heitjans, Phys. Chem. Chem. Phys. 4 (2002) 3246.
[2] D. Bork and P. Heitjans, J. Phys. Chem. B 105 (2001) 9162.