Effect of Li concentration on the ionic conductivity of Li<i>_x</i>La₍₁₋<i>_x</i>_)/3Nb_0.80Ta_0.20O₃ solid solutions

Abstract

In this study, we successfully synthesized Li x La (1¹x)/3 Nb 0.80 Ta 0.20 O 3 solid solutions with different Li concentrations (x = 0.000.30) by a solid-state reaction. With an increase in x, the crystal structure of Li x La (1¹x)/3 Nb 0.80 -Ta 0.20 O 3 initially changed from orthorhombic (0.00¯x¯0.05) to tetragonal (0.10¯x¯0.25) and then from tetragonal to cubic (x = 0.30). Grain sizes of Li x La (1¹x)/3 Nb 0.80 Ta 0.20 O 3 increased with an increase in x. Moreover, densified Li x La (1¹x)/3 Nb 0.80 Ta 0.20 O 3 pellets were obtained. Li x La (1¹x)/3 Nb 0.80 Ta 0.20 O 3 with x = 0.10 showed the highest ionic conductivity of 7.78 © 10 ¹5 S cm ¹1 at room temperature, which decreased with an increase in x from 0.10 to 0.30. Activation energies of Li x La (1¹x)/3 Nb 0.80 Ta 0.20 O 3 were in the range of 0.310.38 eV, which increased with an increase in x.