Peculiarities of ionic transport in Li1.3Al0.15Y0.15Ti1.7(PO4)3 ceramics

• Published in: Journal of physics. Condensed matter Vol. 21; no. 18; pp. 185502 - 185502 (7)
• Main Authors: Šalkus, T, Kazakevičius, E, Kežionis, A, Dindune, A, Kanepe, Z, Ronis, J, Emery, J, Boulant, A, Bohnke, O, Orliukas, A F
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 06.05.2009; Institute of Physics
• Subjects: Condensed matter: structure, mechanical and thermal properties; Diffusion in solids; Exact sciences and technology; Physics; Self-diffusion and ionic conduction in nonmetals; Transport properties of condensed matter (nonelectronic); Grain boundaries; Phosphates; Fluctuations; Electrical conductivity; Temperature effects; Solid state reaction; Ionic conductivity; Nuclear magnetic resonance; Activation energy
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/0953-8984/21/18/185502

A powder of Li1.3Al0.15Y0.15Ti1.7(PO4)3 has been synthesized by solid state reaction. The powder was a single phase material and had rhombohedral symmetry (space group ) with six formula units in the unit cell. Impedance spectra of Li1.3Al0.15Y0.15Ti1.7(PO4)3 ceramics were recorded in the frequency range from 106 to 1.2 X 109 Hz and temperature range from 300 to 600 K. Two relaxation type dispersions of electrical quantities in the frequency range were found. The dispersion regions are presumably related to the ionic transport processes in bulk and grain boundaries of the ceramics. The activation energy of the conductivity of the bulk and the activation energy of the characteristic relaxation frequency, at which the dispersion sets in, has the same value of 0.25 eV. The only contribution of the mobility of Li+ ions defines the temperature dependence of the bulk conductivity in the investigated temperature range. The values of epsilon' may be related to the contributions of the polarization of the fast ionic migration, vibrations of the lattice and electronic polarization. Nuclear magnetic resonance (NMR) investigation shows that the T1 of 7Li and 6Li at room temperature are 6 ms and 2 s respectively. This result confirms that the relaxation of the 7Li nucleus occurs through quadrupolar fluctuations although the relaxation of the 6Li nucleus occurs via dipolar fluctuations. Furthermore, the T1 minimum allows us to evidence a motion with a characteristic frequency in the range of the Larmor frequency.