Effect of lithium substitution with sodium on electrical properties in La0.5Li0.5-xNaxTiO3 and La0.67Li0.2-yNayTi0.8Al0.2O3 solid solutions

Li-containing La0.5Li0.5-xNaxTiO3 and La0.67Li0.2-yNayTi0.8Al0.2O3 solid solutions have been obtained by solid-state reaction route that involves chemical decomposition reactions. Complex impedance spectroscopy measurements demonstrate that the electrical properties in La0.5Li0.5-xNaxTiO3 and La0.67Li0.2-yNayTi0.8Al0.2O3 systems depend on different areas of the ceramic's grain and can be represented by the equivalent circuit consisting of two (when x = 0.5, y = 0.2) and three series-connected elements (0 ≤ x ≤ 0.4, 0 ≤ y ≤ 0.15). It has been shown that an increase in sodium concentration leads to a decrease in the ceramic's grain size for La0.5Li0.5-xNaxTiO3 and La0.67Li0.2-yNayTi0.8Al0.2O3 solid solutions. Substitution of lithium ions by sodium leads to an increase in the unit cell volume of the perovskite structure. It has been demonstrated that La0.67Li0.14Na0.06Ti0.8Al0.2O3 and La0.5Li0.4Na0.1TiO3 materials with low sodium concentration have the maximum value of dielectric constant. •La0.5Li0.5TiO3 with improved dielectric properties were produced using Na.•High permittivity (ε ∼ 4·104 at 1 Hz) was achieved.•The number of vacant sites is controlled by the amount of Na.•The grain bulk and boundary contribute to the electrical properties.