Photoconversion Mechanisms and the Origin of Second-Harmonic Generation in Metal Iodates with Wide Transparency, NaLn(IO) (Ln = La, Ce, Sm, and Eu) and NaLa(IO):Ln (Ln = Sm and Eu).

Four new metal iodates, namely, NaLn(IO) (Ln = La, Ce, Sm, and Eu), and a series of NaLa(IO):Ln (Ln = Sm and Eu) solid solutions were synthesized through hydrothermal reactions. The structures of the title compounds are similar to that of NaY(IO) crystallizing in the acentric monoclinic space group Cc. The iodate materials reveal layered structures composed of LnO square antiprisms and IO polyhedra, in which each layer is connected by the I···O interactions.