Tellurium-oxygen group enhanced birefringence in tellurium phosphates: a first-principles investigation.

ABSTRACT: Phosphates possess a relatively large UV/DUV cutoff edge, but these compounds usually have very small birefringence. Recently the Te₂P₂O₉ crystal was synthesized and its birefringence was reported to be as large as 0.106 at 1013.98 nm. Herein, we investigated the electronic structure and optical properties of Te₂P₂O₉ using the first-principles method. The obtained results are in good agreement with the experimental values. The Born effective charges and SHG density of Te₂P₂O₉ show that the contribution to the birefringence and SHG response mainly originates from the TeO₅ group. The electronic structures and optical response of Ba₂TeO(PO₄)₂ and Te₃O₃(PO₄)₂ were also investigated for comparison. The results show that these two tellurium phosphates also possess a large birefringence similar to Te₂P₂O₉. Also, the birefringence originates from the TeO _x polyhedrons, which was confirmed by the real-space atom-cutting results and distortion indices.

SUBMITTER: Jin P 

PROVIDER: S-EPMC9049004 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature