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Effect of Li+ ion mobility on the grain boundary conductivity of Li2TiO3 nanoceramics
Journal of Advanced Ceramics 2014, 3 (2): 98-108
Published: 01 June 2014
Downloads:14

Lithium titanate (Li2TiO3) is one of the most promising candidates among the tritium breeding materials because of its good tritium release capacity. Li concentration has much significance on the diffusivity of tritium in the material. The nanocrystalline single-phase Li2TiO3 with monoclinic structure has been prepared by high energy ball milling followed by calcination at 700 ℃ for 2 h. The field emission scanning electron microscopy (FESEM) studies confirmed uniform distribution of nanocrystalline phase with particle size below 100 nm. The study of the Li+ ion diffusion on the sintered sample was investigated by means of electrical conductivity measurements. Electrical properties of the samples were studied in wide temperature (50–500 ℃) and frequency (100 Hz–1 MHz) ranges. The complex impedance spectroscopy (CIS) studies showed the presence of both bulk and grain boundary effects in nanocrystalline Li2TiO3. The bulk resistance of the samples has been observed to decrease with rise in temperature showing a typical negative temperature coefficient of resistance (NTCR) behavior. The low activation energies of the samples suggested the presence of singly ionized oxygen vacancies in the conduction process. The hopping frequency shifted toward higher frequency with increase in temperature. Activation energy of 0.86 eV was calculated from AC conductivity.

Open Access Research Article Issue
Electrical properties of bulk and nano Li2TiO3 ceramics:A comparative study
Journal of Advanced Ceramics 2014, 3 (2): 89-97
Published: 01 June 2014
Downloads:25

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.

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