Large Birefringent Materials, Na6Te4W6O29 and Na2TeW2O9: Synthesis, Structure, Crystal Growth, and Characterization
journal contributionposted on 10.02.2016, 16:59 by Hongwei Yu, Weiguo Zhang, P. Shiv Halasyamani
A new d0 transition metal tellurite, Na6Te4W6O29, was synthesized by solid-state methods. The material crystallizes in monoclinic space group P21/c (No. 14) with the following values: a = 7.3297(3) Å, b = 21.9057(9) Å, c = 10.2871(3) Å, β = 133.490(2)°, and Z = 2. Additionally, large crystals of Na6Te4W6O29 (13 mm × 11 mm × 10 mm) and Na2TeW2O9 (23 mm × 5 mm × 3 mm) were grown by the top seeded solution growth method. In addition to the crystal growth, refractive indices were measured, and the Sellmeier equations were fitted by using the minimum deviation technique. Interestingly, the two reported compounds exhibit relatively large birefringences: Δn3 = nz – nx = 0.0828–0.1248 from 1062.6 to 450.2 nm for Na6Te4W6O29, and Δn3 = nz – nx = 0.1471–0.2069 from 1062.6 to 450.2 nm for Na2TeW2O9. The results indicate that Na6Te4W6O29 and Na2TeW2O9 may have uses in applications involving birefrigent materials.