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Journal of Advanced Ceramics

Keywords

nanocrystalline, complex impedance spectroscopy (CIS), AC conductivity, X-ray diffraction (XRD)

Abstract

Nanocrystalline and bulk Li2TiO3 having monoclinic structure were prepared by mechanical alloying as well as conventional ceramic route. Complex impedance analysis in the frequency range of 100 Hz–1 MHz over a wide range of temperature (50–500 ℃) indicates the presence of grain boundary effect along with the bulk contribution. The frequency-dependent conductivity plots exhibit power law dependence, suggesting three types of conduction in the material: low-frequency (100 Hz–1 kHz) conductivity showing long-range translational motion of electrons (frequency independent), mid-frequency (1–10 kHz) conductivity showing short-range hopping of charge carriers and high-frequency (10 kHz–1 MHz) conductivity showing conduction due to localized orientation of hopping mechanism. The electrical conductivity measurement of nanocrystalline and bulk Li2TiO3 with temperature shows the negative temperature coefficient of resistance (NTCR) behavior. The activation energy (0.77 eV for nano sample and 0.88 eV for bulk sample) study shows the conduction mechanism in both samples. The low activation energies of the samples suggest the presence of singly ionized oxygen vacancies in the conduction process.

Publisher

Tsinghua University Press

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