Al-DOPED LANTHANUM-LITHIUM TITANATE WITH HIGH DIELECTRIC CONSTANT

Abstract

La0.67LixTi1-xAlxO3 ceramics (x = 0.05, 0.10, 0.15, 0.20, 0.25, 0.30) were synthesized with the use of Al2O3 and an aqueous solution of Al(NO3)3 as an aluminium source. In both cases, the ceramics preserve a high dielectric constant ε ~ 105. It was found that the single-phase La0.67LixTi1-xAlxO3 perovskite structure is formed at temperatures above 1200  C. It was shown that the use of Al(NO3)3 allows simplifying the synthesis: reduction in the sintering temperature by 20  C, Li loss and, as a result, an increase in the density of ceramics. Ceramics La0.67Li0.15Ti0.85Al0.15O3 with a maximum density higher than 85 % were sintered at about 1280 and 1300  C of with the use of Al(NO3)3 and Al2O3 respectively. Frequency spectra of ima­ginary parts of impedance and electrical modulus demonstrate two dispersion regions that refer to processes in the ceramic grains’ boundaries and ceramic grains. Ceramic samples synthesized using Al(NO3)3 solutions tend to exhibit higher dielectric constants than those synthesized using Al2O3. At a frequency of 100 Hz, the dielectric constant for ceramics synthesized using Al(NO3)3 aqueous solution is 70600, whereas that for ceramics synthesized using Al2O3 is 44300. Obtained materials are useful for microelectronics, energy storage and harvesting devices.