Growth of lithium doped silver niobate single crystals and their piezoelectric properties

Lithium doped silver niobate (Ag1−xLixNbO3, 0 < x < 0.1) is one of the candidate materials for lead-free piezoelectric materials. In this study, Ag1−xLixNbO3 single crystals were successfully grown by a slow cooling method. Crystal structure was assigned to perovskite-type orthorhombic (monoclinic) phase. Dielectric properties were measured as a function of temperature. As a result, with increasing lithium contents, the phase transition at around 60 °C was shifted to lower temperature while the phase transition at around 400 °C was shifted to higher temperature. On the basis of these peak shifts, the lithium contents in Ag1−xLixNbO3 single crystals were determined. Moreover, P–E hysteresis measurement revealed that pure silver niobate crystal was weak ferroelectrics with Pr of 0.095 μC/cm2 while Ag0.9Li0.1NbO3 (ALN10) crystal was normal ferroelectrics with Pr of 10.68 μC/cm2. About this ALN10 crystal, polling treatment was performed and finally piezoelectric properties were measured. As a result, high electromechanical coupling coefficient k31 over 70% was observed.