(H₃O)HCs₂Nb(IO₃)₉ and SrNbO(IO₃)₅: a facile synthetic method using hydrofluoric acid as a solubilizer

By using hydrofluoric acid as a solubilizer, the first alkali-metal niobium iodate and an alkali-earth metal niobium iodate, i.e. (H₃O)HCs₂Nb(IO₃)₉ and SrNbO(IO₃)₅, have been obtained. An obvious cation-controlled polarity shift is observed in the Ae/A-Nb⁵⁺-IO₃ system. (H₃O)HCs₂Nb(IO₃)₉ gives a strong second harmonic generation (SHG) signal about 6 times that of KH₂PO₄ (KDP), making it a promising nonlinear optical (NLO) material.