Synthesis, Structure, Magnetism of Two-Dimensional Triangular Lattice Materials Ba3REB9O18 (RE = Dy, Ho, Er, Tm and Yb)

The synthesis, structure, and magnetic properties of Ba 3 REB 9 O 18 (RE = Dy-Yb) compounds were investigated. Rietveld Refinement of the X-ray diffraction (XRD) data confirms that all compounds crystallize in a hexagonal Ba 3 YB 9 O 18 -type structure with space group P 6 3 /m (No. 176) and Pearson symbol hP 62. The lattice parameters a and c increase linearly with the increasing ionic radii of the RE 3+ ions. RE 3+ ions form two-dimensional triangular layers in the ab plane, which are separated by non-magnetic Ba/B-O polyhedra. The magnetic susceptibility measurement reveals no long-range magnetic order or spin glass behavior in any of the compounds above 2 K. The negative Curie-Weiss temperatures indicate dominant antiferromagnetic (AFM) exchange interactions between the RE 3+ ions. The combination of triangular lattice and antiferromagnetic interaction suggests this family of compounds is a promising system for researching magnetic frustration.