Functional Materials Design via Structural Regulation Originated from Ions Introduction: A Study Case in Cesium Iodate System

Abstract

Tailored structural regulation to achieve novel compounds with special properties is very attractive and important for functional material design. In this paper, CsIO 3 was selected as a maternal structure and three new derivatives, namely, CsIO 2 F 2, Cs 3 (IO 2 F 2 ) 3 ·H 2 O, and Cs(IO 2 F 2 ) 2 ·H 5 O 2, were successfully prepared by introducing different units (F –, H 2 O, H 5 O 2 +, and IO 2 F 2 – ) under hydrothermal condition for the first time. Then, the structural transformations were schematically analyzed and the corresponding properties originated from ions introduction were investigated. Therein, noncentrosymmetric CsIO 3 and CsIO 2 F 2 exhibit good nonlinear optical properties with large second-harmonic generation (SHG) effects (15 × and 3 × KH 2 PO 4 ), wide band gaps (4.2 and 4.5 eV), wide transmittance ranges (∼0.27–5.5 μm), and high laser damage thresholds (15 × and 20 × AgGaS 2, respectively), which shows that they are potential nonlinear optical materials in near-ultraviolet to mid-infrared. To further analyze the structure–properties relationship, the first-principles calculations are applied to explore the origins of the optical properties, such as birefringences and SHG responses. Moreover, the protonated (H 5 O 2 ) + cations in Cs(IO 2 F 2 ) 2 ·H 5 O 2 imply that it may feature enhanced conductivity, which was tentatively verified by the resistivity tests via the conventional dc four-probe method. The study case of structural regulation realized by ions introduction in this work may give a feasible guidance for functional materials design.