Luminescent lanthanide selenites and tellurites decorated by MoO ₄ tetrahedra or MoO₆ octahedra: Nd₂MoSe ₂O₁₀, Gd₂MoSe₃O₁₂, La₂MoTe₃O₁₂, and Nd₂MoTe ₃O₁₂

Solid state reactions of lanthanide oxide, MoO₃ and SeO ₂ (or TeO₂) at high temperature in an evacuated quartz tube lead to four new Ln-Mo-Se(Te)-O quaternary phases with four different types of structures, namely, Nd₂-MoSe₂O₁₀, Gd ₂MoSe₃O₁₂, La₂MoTe₃O ₁₂, and Nd₂MoTe₃O₁₂. The structure of Nd₂MoSe₂O₁₀ features a 3D architecture built by the intergrowth of the Nd-Se-O layers with the Nd-Mo-O layers. The structure of Gd₂MoSe₃O₁₂ contains a 3D network of gadolinium selenite with the MoO₆ octahedra occupying the cavities of the structure. The structure of La₂MoTe₃O₁₂ features a 3D network of La₂(Te₃O₈) ²⁺ with the tunnels along the a axis occupied by the MoO₄ tetrahedra. Nd₂MoTe₃O₁₂ features a 2D layer built by the lanthanide ions interconnected by tellurite groups and ditellurite groups, with the MoO₄ tetrahedra as the interlayer pendant groups. Room temperature and low temperature luminescent studies indicate that Nd ₂MoSe₂O₁₀ and Nd₂MoTe ₃O₁₂ exhibit strong luminescence in the near-IR region.