Coexistence of Long-Range Magnetic Order and Magnetic Frustration of a Novel Two-Dimensional S = 1/2 Structure: Na₂Cu₃(SeO₃)₄

Novel quantum materials offer the opportunity to expand next-generation computers, high-precision sensors, and new energy technologies. Among the most important factors influencing the development of quantum materials research is the ability of inorganic and materials chemists to grow high-quality single crystals. Here, the synthesis, structure characterization and magnetic properties of Na₂Cu₃(SeO₃)₄ are reported. It exhibits a novel two-dimensional (2D) structure with isolated layers of Cu nets. Single crystals of Na₂Cu₃(SeO₃)₄ were grown using a low-temperature hydrothermal method. Single-crystal X-ray diffraction reveals that Na₂Cu₃(SeO₃)₄ crystallizes in the monoclinic crystal system and has space group symmetry of P2₁/n (No.14) with a unit cell of a = 8.1704(4) Å, b = 5.1659(2) Å, c = 14.7406(6) Å, β = 100.86(2), V = 611.01(5) ų and Z = 2. Na₂Cu₃(SeO₃)₄ comprises a 2D Cu-O-Cu lattice containing two unique copper sites, a CuO₆ octahedra and a CuO₅ square pyramid. The SeO₃ groups bridge the 2D Cu-O-Cu layers isolating the neighboring Cu-O-Cu layers, thereby enhancing their 2D nature. Magnetic properties were determined by measuring the magnetic susceptibility of an array of randomly oriented single crystals of Na₂Cu₃(SeO₃)₄. The temperature-dependent magnetic measurement shows an antiferromagnetic transition at T_N = 4 K. These results suggest the fruitfulness of hydrothermal synthesis in achieving novel quantum materials and encourage future work on the chemistry of transition metal selenite.