Synthesis, structure and characterization of Cd2TeO3Cl2 with unprecedented [Cd2O6Cl4] octahedral dimers

Abstract

A new mixed anionic compound Cd₂TeO₃Cl₂ with unprecedented [Cd₂O₆Cl₄] octahedral dimers has been synthesized, and millimeter-scale single crystals of Cd₂TeO₃Cl₂ have been grown by the vertical Bridgman method with CdCl₂ as the flux. Cd₂TeO₃Cl₂ crystallizes in the centrosymmetric P (no. 2) space group, and shows a mixed cationic layer structure constituted by distorted [TeO₃] motifs, mixed anionic [Cd₂O₆Cl₄] chains, and [Cd₂O₆Cl₄] octahedral dimers. Experimental and theoretical results show that Cd₂TeO₃Cl₂ is a direct band gap compound with an experimental band gap of ∼4.25 eV. Meanwhile, the compound has good optical transmittance in the 3–5 μm atmospheric window. The results indicate that Cd₂TeO₃Cl₂ could be used as a promising mid-IR window material, and could enrich the chemical and structural diversity of oxides.