Dielectric, Piezoelectric, and Elastic Properties of a Polar Crystal Rb₄Li₂TiOGe₄O₁₂

The Rb4Li2TiOGe4O12 (RLTG) crystal has been found to be a high damage threshold mid-infrared nonlinear optical material. Its electromechanical properties have to be studied for it has a polar structure and high symmetry. In this paper, based on a recently grown crystal with dimensions up to 43 x 40 x 26 mm(3), the dielectric, piezoelectric, and elastic constants of RLTG were measured by the resonance technique at room temperature. It shows a considerable piezoelectric constant of d(33) = 10.08 pC/N, much better than that of the available alpha-SiO2 (d(11) =2.3 pc/N). Additionally, the relations between the structure and electric-elastic anisotropy are also discussed in detail. The results illustrate that RLGT is an attractive candidate for piezoelectric applications with a large piezoelectric coefficient, good chemical stability, high symmetry, and easiness in crystal growth.