Explorations of a Series of Second Order Nonlinear Optical Materials Based on Monovalent Metal Gold(III) Iodates

The
syntheses, crystal structures, and characterizations of a series of
monovalent metal gold­(III) iodates, namely, α-NaAu­(IO3)4, β-NaAu­(IO3)4, RbAu­(IO3)4, α-CsAu­(IO3)4, β-CsAu­(IO3)4, and AgAu­(IO3)4 are reported.
Their structures feature Au­(IO3)4– anions that are separated by alkali metal ions or silver­(I) ions.
The Au­(IO3)4– anions in the
polar α-NaAu­(IO3)4, RbAu­(IO3)4, and α-CsAu­(IO3)4 are polar
with all four iodate groups being located only above (or below) the
AuO4 square plane (cis- configuration).
α-NaAu­(IO3)4, RbAu­(IO3)4, and α-CsAu­(IO3)4 display moderate
strong Second-Hamonic Generation (SHG) responses of 1.17 ×, 1.33
×, and 1.17 × KTP (KTiOPO4), respectively, and
all three materials are type-I phase-matchable. The Au­(IO3)4– anions in centrysymmetric β-NaAu­(IO3)4, β-CsAu­(IO3)4, and
AgAu­(IO3)4 are nonpolar with the four iodate
groups of the Au­(IO3)4– anion
being located both above and below the AuO4 square plane
(trans- configuration). IR and UV spectra, luminescent
and ferroelectric properties have also been measured. Theoretical
calculations of their optical properties based on density functional
theory (DFT) methods were performed by using the CASTEP total-energy
code.