Synthesis, structure and characterization of CdTeOCl with unprecedented [CdOCl] octahedral dimers.

A new mixed anionic compound CdTeOCl with unprecedented [CdOCl] octahedral dimers has been synthesized, and millimeter-scale single crystals of CdTeOCl have been grown by the vertical Bridgman method with CdCl as the flux. CdTeOCl crystallizes in the centrosymmetric 1̄ (no. 2) space group, and shows a mixed cationic layer structure constituted by distorted [TeO] motifs, mixed anionic [CdOCl] chains, and [CdOCl] octahedral dimers. Experimental and theoretical results show that CdTeOCl 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 CdTeOCl could be used as a promising mid-IR window material, and could enrich the chemical and structural diversity of oxides.