Synthesis, structure, and characterization of a new second-harmonic-generating tellurite:: Na2TeW2O9

The synthesis, structure, and characterization of a new noncentrosymmetric tellurite, Na2TeW2O9, is reported. The oxide exhibits a three-dimensional structure comprising distorted W-6+O-6 octahedra linked to asymmetric Te4+O3 groups. Both cations are in local acentric environments attributable to second-order Jahn-Teller effects. Single crystals of Na2TeW2O9 were synthesized through supercritical hydrothermal methods, utilizing NaOH(aq), WO3, and TeO2 as reagents. Polycrystalline Na2TeW2O9 was synthesized by combining stoichiometric amounts of Na2CO3, WO3, and TeO2 through standard solid-state methods. Na2TeW2O9 crystallizes in the noncentrosymmetric space group Ia (No. 9) with a = 13.1394(5) Angstrom, b = 7.3202(3) A, c = 31.4435(11) Angstrom, and beta = 95.0270(10)degrees. Powder SHG measurements, using 1064-nm radiation, on polycrystalline Na2TeW2O9 indicated a strong SHG intensity of approximately 500x SiO2. Additional SHG measurements revealed the material is phase-matchable (Type I).