A series of new alkali metal indium iodates with isolated or extended anions

Abstract

Systematic explorations of new phases in the A^I–In^III–I^V–O system by hydrothermal reactions led to five new compounds, namely, AIn(IO₃)₄ (A = Li, Na), Rb₃In(IO₃)₆ and A₂HIn(IO₃)₆ (A = Rb, Cs). The structure of AIn(IO₃)₄ (A = Li, Na) contains one-dimensional [In(IO₃)₄]⁻ chains separated by Li⁺ or Na⁺ cations. In both compounds, each In³⁺ cation is octahedrally coordinated by six IO₃⁻ anions, neighboring In³⁺ cations are interconnected by bidentate bridging iodate anions into 1D chains. The structures of Rb₃In(IO₃)₆ and A₂HIn(IO₃)₆ (A = Rb, Cs) all feature isolated [In(IO₃)₆]³⁻ anions with alkali metal ions (and H⁺ ions) as spacers. Both optical diffuse reflectance spectrum measurements and band structure calculations based on DFT methods indicate that LiIn(IO₃)₄, NaIn(IO₃)₄, and Rb₂HIn(IO₃)₆ are insulators.