Explorations of new quaternary phases in the LnIII–VV(d0)–SeIV–O (Ln = Nd, Eu, Gd, Tb) systems

Abstract

Systematic explorations of new phases in the Ln^III–V^V–Se^IV–O systems by hydrothermal syntheses led to four new quaternary compounds, namely, Nd₂(V^V₂O₄)(SeO₃)₄·H₂O (1), Ln(V^VO₂)(SeO₃)₂ (Ln = Eu 2, Gd 3, Tb 4). The structure of Nd₂(V^V₂O₄)(SeO₃)₄·H₂O features a 3D framework composed of the 2D layers of [N d(SeO₃)]⁺ bridged by the infinite [VO₂(SeO₃)]⁻ chains with the lattice water molecules located at the 6-membered ring tunnels formed. The structure of Ln(V^VO₂)(SeO₃)₂ (Ln = Eu, Gd, Tb) also features a 3D framework composed of 2D layers of [Ln(SeO₃)]⁺ bridged by the infinite [(VO₂)(SeO₃)]⁻ double chains. The 1D vanadium oxide selenite chain of 1 differs significantly from those in compounds 2–4 in terms of the coordination modes of the selenite groups and the connectivities between neighbouring VO₆ octahedra. Luminescent and magnetic properties of these compounds were also measured.