LAUSR

The physicochemical characteristics of the crystal–melt system during the growth of LiNbO3: ZnO crystals have been investigated in the range of impurity concentration [ZnO] in the melt of 4.02–8.91 mol %. The threshold impurity concentration corresponding to a significant change in the formation conditions and structure of LiNbO3: ZnO crystals is refined ([ZnO] = 6.76 mol % in the melt). The dielectric and piezoelectric properties and conductivity of multidomain LiNbO3: ZnO crystals have been analyzed. The occurrence of a significant spontaneous increase in the unipolarity upon high-temperature annealing has only been shown to be typical of LiNbO3: ZnO crystals grown from melts in the near-threshold concentration range (~5.4 < [ZnO] ≤ 6.76 mol % in the melt). This effect is accompanied by a large and reproducible increase in the static piezoelectric coefficient d333. The value of the piezoelectric-coefficient jump Δd333 linearly increases with an increase in the specific-conductivity jump Δσ near the temperature T* ≈ 800 K.