From Ag2 Zr(IO3 )6 to LaZr(IO3 )5 F2 : A Case of Constructing Wide-band-gap Birefringent Materials through Chemical Cosubstitution.

Two mixed-metal zirconium iodates were prepared and studied as a case of chemical cosubstitution. The structure of Ag2 Zr(IO3 )6 (P21 /c) features 0D [Zr(IO3 )6 ]2- anion group and 1D [Ag(IO3 )2 ]- anionic chain, with the [Zr(IO3 )6 ]2- anion groups interconnected by Ag+ ions into 3D network; LaZr(IO3 )5 F2 (P21 /n) features 0D [Zr(IO3 )5 F2 ]3- anion group and 2D [La(IO3 )5 ]2- anionic layer, with the [Zr(IO3 )5 F2 ]3- groups interlinked by La3+ ions into 3D structure. Notably, LaZr(IO3 )5 F2 is the first zirconium iodate fluoride reported. Wide optical band gaps of 3.77 and 4.13 eV are given for Ag2 Zr(IO3 )6 and LaZr(IO3 )5 F2 , respectively. Theoretical calculations confirmed that the weak d-d transition of Zr4+ in the band structure leads to a moderate band gap of Ag2 Zr(IO3 )6 , and the introduction of F- into the zirconium iodate compound results in a large band gap of LaZr(IO3 )5 F2 . Both of the compounds are birefringent materials with birefringences of 0.064 @1064 nm and 0.082 @1064 nm, respectively.