Investigation of the Piezoelectric Resonance in Stoichiometric LiNbO₃ Crystals at High Temperatures and Conductivities

The piezoelectric characteristics, dielectric properties, and ionic conductivity of close-to-stoichiometry LiNbO${}_{3_{\text{stoich}}}$ crystals have been investigated in a wide temperature range (300–850 K) with the aim of establishing the conditions of use of lithium-niobate-based piezoelectric resonators at high temperatures and, accordingly, high conductivities. It is shown that the piezoelectric phenomenon in LiNbO${}_{3_{\text{stoich}}}$ crystals is observed in a certain temperature range ΔT (and, correspondingly, at certain static-conductivity relaxation times Δτ_V) and a frequency range Δω_R at the condition ${\tau }_V^{-1}$$\ll$ ω_R satisfied. Apparently, not only LiNbO${}_{3_{\text{stoich}}}$ crystals exhibit such regularities, but also some other piezoelectric materials.