Sol-gel synthesis, structure, and dielectric properties of La(0.67)Li(x)Ti(1-x)Al(x)O(3) solid solutions

La(0.67)Li(x)Ti(1-x)Al(x)O(3) were synthesized using the sol-gel Pechini route. Ceramic samples were sintered in the temperature range of 1240–1300 °C in the air atmosphere. It was found that in the concentration range of 0.05 ≤ x < 0.15 there is a morphotropic phase boundary region with rhombohedral and tetragonal syngonies. In the concentration range of 0.15 ≤ x ≤ 0.3, a single-phase solid solution with rhombohedral R [Formula: see text] c syngony is formed. As the value of x increases, the average grain size of La(0.67)Li(x)Ti(1-x)Al(x)O(3) ceramics increases from 5.23 μm (x = 0.05) to 8.76 μm (x = 0.3). All materials of the La(0.67)Li(x)Ti(1-x)Al(x)O(3) system at 0.05 ≤ x ≤ 0.3 have colossal values of dielectric constant ε′ > 10(4) at frequencies up to 1 kHz. La(0.67)Li(x)Ti(1-x)Al(x)O(3) (x = 0.2) solid solution with rhombohedral syngony has the highest value of dielectric constant and the lowest value of the dielectric losses.