AIO3·H6TeO6 (A = NH4+, Rb+): Two telluric acid and iodate Co-crystalline compounds with second harmonic generation response

Two co-crystalline compounds containing telluric acid and iodate, namely AIO3·H6TeO6 (A ​= ​Rb+, NH4+), were investigated as potential nonlinear optical materials. They crystallize into isostructural and consist of isolated [IO3] group and [H6TeO6] molecule linked by hydrogen bonds and charge interactions of Rb+/NH4+. They show phase-matching second harmonic generation responses with moderate intensity of 1.2 ​× ​KDP (Rb+) and 1.1 ​× ​KDP (NH4+). They also possess large optical band gaps over 4.25 ​eV and can be easily grown from aqueous solutions. The local dipole moment calculations based on the structures of AIO3·H6TeO6 (A ​= ​K+, Rb+, NH4+) series of compounds indicate that the change of A+ cation in their structural frame causes a slight change in the arrangement directions of [IO3] and [Te(OH)6] groups, and further induces their SHG responses of different intensities at the macroscopic level.