A new iodate-phosphate Pb2(IO3)(PO4) achieving great improvement in birefringence activated by (IO3)- groups.

The first divalent-metal iodate-phosphate, Pb2(IO3)(PO4), has been prepared via the strategy of introducing (IO3)- into phosphate. The structure features a unique 3D network where [Pb(IO3)]∞+ and [Pb(PO4)]∞- layers are alternatively interconnected. The birefringence of Pb2(IO3)(PO4) is greatly increased to 0.060 at 1064 nm.