α-AgI3O8 and β-AgI3O8 with Large SHG Responses: Polymerization of IO3 Groups into the I3O8 Polyiodate Anion

• DOI: 10.1021/cm500898q
• Publication Date: 2014-04-25T16:39:40Z
• Authors: Xiang Xu; Chun-Li Hu; Bing-Xuan Li; Bing-Ping Yang; Jiang-Gao Mao
• Keywords: Thermal Stability

Two new noncentrosymmetric isomeric silver polyiodates, namely, α-AgI3O8 (Pnc2) and β-AgI3O8 (I4̅), have been synthesized through the hydrothermal reactions of AgNO3 with I2O5. Both isomers exhibit layered structures that are constructed from I3O8– anions interconnected by Ag+ cations. The main structural difference between two lies in different stacking fashions [AgI3O8] layers along c axis order to meet requirements their space groups. Powder second-harmonic generation (SHG) measurements indicate both phase-matchable materials large SHG responses approximately 9.0 8.0 times KH2PO4, respectively. UV–vis–NIR transmission spectra show cutoff absorption edges 328 nm for 345 β-AgI3O8. Thermal stability studies demonstrate thermally stable up about 370 °C. Theoretical calculations based on DFT methods AgI3O8 phases as well NaI3O8 analogue performed.