Synthesis, Structure, and Characterization of a New Second-Harmonic-Generating Tellurite: Na₂TeW₂O₉

The synthesis, structure, and characterization of a new noncentrosymmetric tellurite, Na 2 TeW 2 O 9, is reported. The oxide exhibits a three-dimensional structure comprising distorted W 6+ O 6 octahedra linked to asymmetric Te 4+ O 3 groups. Both cations are in local acentric environments attributable to second-order Jahn−Teller effects. Single crystals of Na 2 TeW 2 O 9 were synthesized through supercritical hydrothermal methods, utilizing NaOH (aq), WO 3, and TeO 2 as reagents. Polycrystalline Na 2 TeW 2 O 9 was synthesized by combining stoichiometric amounts of Na 2 CO 3, WO 3, and TeO 2 through standard solid-state methods. Na 2 TeW 2 O 9 crystallizes in the noncentrosymmetric space group Ia (No. 9) with a = 13.1394(5) Å, b = 7.3202(3) Å, c = 31.4435(11) Å, and β = 95.0270(10)°. Powder SHG measurements, using 1064-nm radiation, on polycrystalline Na 2 TeW 2 O 9 indicated a strong SHG intensity of approximately 500× SiO 2 . Additional SHG measurements revealed the material is phase-matchable (Type I).