K2TeP2O8: a new telluro-phosphate with a pentagonal Te–P–O layer structure

Abstract

A new telluro-phosphate K₂TeP₂O₈ was synthesized by a high temperature solution method. It crystallizes in the orthorhombic space group P2₁2₁2 and features a [TeP₂O₈]²⁻ layer structure, which is the first layer structure built by Te–O and P–O groups among the telluro-phosphates. More interestingly, the layer structure in K₂TeP₂O₈ is nearly pentagonal. First-principles theoretical calculations suggest that K₂TeP₂O₈ possesses a large birefringence compared to phosphates. Furthermore, IR spectra, UV-vis-NIR diffuse reflectance spectroscopy data, thermal behavior, and electronic structure calculations were studied.