Cooperation of Three Chromophores Generates the Water-Resistant Nitrate Nonlinear Optical Material Bi3 TeO6 OH(NO3 )2.

Abstract

Nitrates have long been ignored for practical uses as nonlinear optical (NLO) materials because they are usually very easy to dissolve in water; despite this, the π-conjugated [NO3 ]- is among the most desirable NLO-active structural units. The cooperation of three structural chromophores, namely, Bi3 O6 OH short chains with 6s2 lone pair electrons, distorted TeO6 octahedra with d10 electrons, and π-conjugated [NO3 ]- triangles, generates a new nitrate NLO material, Bi3 TeO6 OH(NO3 )2 , which exhibits an enhanced phase-matchable NLO response of three times that of KH2 PO4 (3×KH2 PO4 ), exceeding those of most nitrate NLO materials. Remarkably, the new material did not show obvious weight loss and degeneration of NLO response after being dipped in de-ionized water for 24 h, indicating that it is highly resistant to water. Theoretical calculations reveal that foreign water molecules cannot stably stay in the crystal lattice of Bi3 TeO6 OH(NO3 )2 . These findings highlight the introduction of diverse chromophores into the nitrate systems as an effective approach for developing practical nitrate NLO materials that are of high water-resistance and good optical performance.