Dependence of electrical properties on the concentration of tantalum in ceramics Li0.12Na0.88TayNb1-yO3 (y = 0.15, 0.2, 0.25) obtained at high pressure

We have obtained for the first time ferroelectric solid solutions (i.e. ceramic) Li_0.12Na_0.88Ta_yNb_1-yO₃ (y = 0.15, 0.2, 0.25) with the perovskite structure under conditions of high pressures and temperatures. Their electrophysical characteristics have been studied. It has been established that the solid solutions ceramic samples have an orderly distorted crystal structure. The values of static specific conductivities have been determined as functions of temperature, the activation energy of charge carriers, and the real part of the permittivity. It has been established that the samples experience a number of successive phase transitions. For example, P → R → S(T₂). It has been found that the electrical conductivity increases when the content of tantalum increases. The Li_0.12Na_0.88Ta_0.25Nb_0.75O₃ ceramic sample has atypically high electrical conductivity values (close to high ionic conductivity) for this class of solid solutions over the entire studied temperature range. At the same time, the phase is metastable, and heating above the Curie temperature leads to its gradual destruction.