Dielectric and piezoelectric properties and electrical conductivity of LiNbO3:ZnO crystals in a wide range of dopant concentrations

Abstract

The dielectric and piezoelectric properties and electrical conductivity of initially multidomain LiNbO₃:ZnO crystals have been studied in a wide range of dopant concentrations with the aim of determining the composition range of the anomalous increase in unipolarity. The results demonstrate that the development of spontaneous unipolarity during high-temperature annealing takes place only in LiNbO₃:ZnO crystals grown from melts in a “near-threshold” composition range (~5.4 < C_m ≤ 6.76 mol % ZnO). The effect is accompanied by a considerable and reproducible increase in the static piezoelectric modulus d₃₃₃. The increase in the piezoelectric modulus, Δd₃₃₃, rises linearly with increasing jump in electrical conductivity, Δσ, near a temperature T* ≈ 800 K.