From Ag 2 Zr(IO 3 ) 6 to LaZr(IO 3 ) 5 F 2 : 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 Ag 2 Zr(IO 3 ) 6 ( P 2 1 /c ) features 0D [Zr(IO 3 ) 6 ] 2− anion group and 1D [Ag(IO 3 ) 2 ] − anionic chain, with the [Zr(IO 3 ) 6 ] 2− anion groups interconnected by Ag + ions into 3D network; LaZr(IO 3 ) 5 F 2 ( P 2 1 /n ) features 0D [Zr(IO 3 ) 5 F 2 ] 3− anion group and 2D [La(IO 3 ) 5 ] 2− anionic layer, with the [Zr(IO 3 ) 5 F 2 ] 3− groups interlinked by La 3+ ions into 3D structure. Notably, LaZr(IO 3 ) 5 F 2 is the first zirconium iodate fluoride reported. Wide optical band gaps of 3.77 and 4.13 eV are given for Ag 2 Zr(IO 3 ) 6 and LaZr(IO 3 ) 5 F 2 , respectively. Theoretical calculations confirmed that the weak d – d transition of Zr 4+ in the band structure leads to a moderate band gap of Ag 2 Zr(IO 3 ) 6 , and the introduction of F − into the zirconium iodate compound results in a large band gap of LaZr(IO 3 ) 5 F 2 . Both of the compounds are birefringent materials with birefringences of 0.064 @1064 nm and 0.082 @1064 nm, respectively.