Top-Seeded Solution Crystal Growth and Functional Properties of a Polar Material-Na2TeW2O9

Centimeter-size single crystals of the noncentrosymmetric and polar material Na2TeW2O9 were successfully grown through a top-seeded solution growth (TSSG) method. Differently oriented seeds, along the [100], [010], and [001] directions, were used to grow large single crystals. The morphologies of the grown crystals with different oriented seeds are described. Na2TeW2O9 crystallizes in the noncentrosymmetric and polar monoclinic space group la (No. 9). Functional properties including piezoelectricity and polarization were also measured. The d(11) and d(33) piezoelectric coefficients are 4.0 pC/N and 13.9 pC/N, respectively. Polarization measurements indicate that although Na2TeW2O9 is polar, the material is not ferroelectric; that is, the polarization is not switchable. In addition, optical measurements indicate a UV absorption edge near 360 nm, with a transmission window up to 5 mu m.