Growth of Large-Scale Silver Lithium Niobate Single Crystals and Their Piezoelectric Properties

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Silver lithium niobate (Ag1-xLixNbO3, $0<x<0.1$, ALN) single crystals were grown by a slow cooling method without flux under oxygen flow. By optimizing growth conditions, Ag0.9Li0.1NbO3 (ALN10) crystals with sizes of ca. 30 mm cube were successfully grown in this study. The crystal symmetries in the ALN system were investigated by high energy X-ray diffraction (XRD) measurement, and finally, the space group of the ALN10 crystals at 24 °C was assigned to a ferroelectric $Pc2_{1}b$ orthorhombic symmetry. The ALN10 crystals were oriented using the back reflection Laue method along the [010]o and [110]o directions, and the polarization–electric field ($P$–$E$) hysteresis loop was measured along these two directions. The $P_{\text{r}}$ of [010]o oriented ALN10 crystals was 21 μC/cm2, while that of [110]o oriented ALN10 crystals was 15 μC/cm2. The $P_{\text{r}}$ along the [010]o direction was $\sqrt{2}$ times larger than that along the [110]o direction, confirming that the [010]o direction is the polar direction. Moreover, these piezoelectric properties were measured using the 31 resonators of the ALN10 crystals as a function of crystallographic orientation, i.e., [010]o or [110]o.
2006-09-30