Synthesis and characterization of three new rare-earth orthoborates: Ba2MgY2(BO3)4, Ba2CdY2(BO3)4, and Ba2CdSc(BO3)3

Abstract

Three rare-earth orthoborates Ba₂MgY₂(BO₃)₄, Ba₂CdY₂(BO₃)₄, and Ba₂CdSc(BO₃)₃ were synthesized via a high-temperature solution method and their structures were determined by single crystal X-ray diffraction for the first time. Ba₂MgY₂(BO₃)₄ and Ba₂CdY₂(BO₃)₄ are isostructural and both crystallize in the monoclinic crystal system, P2₁/c, while Ba₂CdSc(BO₃)₃ crystallizes in the triclinic crystal system, P. The structures of Ba₂MgY₂(BO₃)₄ and Ba₂CdY₂(BO₃)₄ can be described as the three-dimensional (3D) frameworks composed of MO₅ (M = Mg, Cd), YO_n (n = 6, 7) polyhedra with isolated BO₃ and Ba²⁺ cations residing in the space of the frameworks. The structure of Ba₂CdSc(BO₃)₃ is composed of 2D [CdSc(BO₃)₃]_∞ layers separated by Ba²⁺ cations. In addition, structural comparisons, thermal behaviors, UV-vis-NIR diffuse reflectance spectra, and infrared spectroscopy results are also reported.