Synthesis, structure, and magnetic properties of the novel sodium cobalt tellurate Na5Co15.5Te6O36

• A single crystal of Na5Co15.5Te6O36 has been synthesized by a self-flux method.
• Na5Co15.5Te6O36 crystallizes in hexagonal symmetry with a space group P63/m.
• Na5Co15.5Te6O36 has an antiferromagnetic ordering with a Neel temperature of 52 K.
• Na5Co15.5Te6O36 shows anisotropic ferro- and antiferromagnetism at low temperatures.

The novel single crystal oxide Na5Co15.5Te6O36 had been successfully synthesized by a self-flux method. Na5Co15.5Te6O36 crystallizes in hexagonal symmetry, space group P63/m (No.176), with lattice parameters a=9.359 (3) Å, c=9.096 (8) Å, and Z=1. The structure is composed of combining the edge-sharing chains of octahedra, [TeO6]6− and [Co(1)O6]10− with the face-sharing chains of triangular prisms, [Co(2)O6]10− and [Co(3)(Na(3))O6]10−. Sodium ions partially occupy hexagonal channels along the c-axis that are formed by the connection of the chains. The magnetic susceptibility data show a long-range antiferromagnetic ordering with a Neel temperature of 52 K along the c axis. At temperatures above 200 K, the susceptibility corrected for the diamagnetic contribution can be fit to the Curie–Weiss law for Co2+ (S=3/2). The anisotropic ferromagnetic and antiferromagnetic feature of Na5Co15.5Te6O36 was obtained through field-dependent magnetization measurements at low temperature. The ferromagnetic and antiferromagnetic behaviors can be considered from the interactions between the Co ions in 1D zig-zag chains formed by sharing the edges of the Co(1)O6 octahedra, and the interactions between the interchain Co ions, respectively.

The unit cell (a) and perspective view along [001] (b) of novel single crystal oxide, Na5Co15.5Te6O36.Figure optionsDownload as PowerPoint slide