"All-Three-in-One": A New Bismuth-Tellurium-Borate Bi₃TeBO₉ Exhibiting Strong Second Harmonic Generation Response

A new nonlinear optical (NLO) material, Bi₃TeBO₉ (BTBO), is successfully grown from high temperature solution method. BTBO crystallizes in a polar space group of P6₃ with a framework structure composed of [Bi₃O₉] blocks, with TeO₆ and BO₃ interconnection. It is interesting that in the BTBO structure three types of NLO-active units, including stereochemically active lone pair cations (Bi³⁺ cations), second-order Jahn-Teller distorted octahedra (TeO₆ octahedra) and π-orbital planar groups (BO₃ groups), simultaneously exist. The additive contribution from these three types of groups results in an extremely large second harmonic generation (SHG) response in BTBO (about 20 times that of KDP), exhibiting the largest SHG effect among the known borate NLO materials. The enhancement of the nonlinear optical property is elucidated by the first-principles analysis.