Two new tellurite halides with cationic layers: syntheses, structures, and characterizations of CdPb2Te3O8Cl2 and Cd13Pb8Te14O42Cl14

Abstract

Two new tellurite halides, CdPb₂Te₃O₈Cl₂ and Cd₁₃Pb₈Te₁₄O₄₂Cl₁₄, with cationic layer structures have been synthesized by high-temperature solution method. CdPb₂Te₃O₈Cl₂ crystallizes in the noncentrosymmetric Aba2 space group, built by [CdPb₂Te₃O₈] cationic layers with Cl atoms. Cd₁₃Pb₈Te₁₄O₄₂Cl₁₄ crystallizes in the centrosymmetric P space group, constructed by [Cd₁₂Pb₄Te₈O₅₃] layers, and [Cd7Cl₆] octahedra as well as Cl atoms filled the interlayers. In the two compounds, four unique oxyhalide mixed anionic groups, [CdO₆Cl], [PbO₃Cl₄], [PbO₄Cl₄] and [PbO₃Cl₅], were discovered. The experimental bands are ∼3.89 eV for CdPb₂Te₃O₈Cl₂ and ∼3.78 eV for Cd₁₃Pb₈Te₁₄O₄₂Cl₁₄. Furthermore, the powder second harmonic generation (SHG) response of CdPb₂Te₃O₈Cl₂ is about 0.2 × AgGaS₂ at 2029 nm (× 1.1 KDP@1064 nm), which mainly originates from the triangular [TeO₃] and distorted [TeO₄] units. The results give an insight into the design of new IR optical materials by combining the heavy metal oxyhalide groups with the Te–O units.