Physicochemical, dielectric, and piezoelectric properties and conductivity of LiNbO$_{3}$ : ZnO crystals (4.02–8.91 mol.%)

The physicochemical characteristics of the crystal–melt system during the growth of LiNbO$_3$ : 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 LiNbO$_3$ : ZnO crystals is refined ([ZnO] = 6.76 mol % in the melt). The dielectric and piezoelectric properties and conductivity of multidomain LiNbO$_3$: 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 LiNbO$_3$ : ZnO crystals grown from melts in the near-threshold concentration range ($\sim$5.4 < [ZnO] $\le$ 6.76 mol % in the melt). This effect is accompanied by a large and reproducible increase in the static piezoelectric coefficient $d_{333}$. The value of the piezoelectric-coefficient jump $\Delta d_{333}$ linearly increases with an increase in the specific-conductivity jump $\Delta\sigma$ near the temperature $T^*\approx$ 800 K.