High-Pressure Synthesis and Crystal Structure of the Highly Condensed Yttrium Borate YB7O12

Abstract

The yttrium borate YB7O12 was obtained in a high-pressure/high-temperature experiment at 10 GPa and 1573 K. The crystal structure was clarified by X-ray single-crystal diffraction, where the compound was found to crystallize in the orthorhombic space group Pccn (no. 56) with the lattice parameters a = 11.985(2), b = 6.717(6), c = 7.867(7) Å, and a volume of V = 633.0(1) Å3. Built up exclusively from BO4 tetrahedra, YB7O12 features an exceptionally high degree of condensation, which originates from the finding that every tetrahedron contains two threefold-coordinated oxygen atoms. The compound was further characterized by X-ray powder diffraction.