Lone‐Pair Enhanced Birefringence in an Alkaline‐Earth Metal Tin(II) Phosphate BaSn2(PO4)2.

The first alkaline‐earth metal tin(II) phosphate, BaSn2(PO4)2, has been discovered, which consists of layered structures constructed from strictly alternating [SnO3]4− and [PO4]3− moieties. This compound is expected to have a large birefringence with Δn≈0.071 at 1064 nm, owing to the presence of stereochemically active lone pair metal cations. [ABSTRACT FROM AUTHOR]