High-pressure Synthesis, Crystal Structure, and Properties of the First Ternary Zirconium Borate β-ZrB 2 O 5

The high-pressure phase β -ZrB 2 O 5 represents the first ternary borate in the system Zr-B-O. The compound was synthesized under high-pressure / high-temperature conditions of 7.5 GPa and 1100 °C in a Walker-type multianvil apparatus. The crystal structure was determined on the basis of single crystal X-ray diffraction data, collected at room temperature. The monoclinic zirconium borate crystallizes in the space group P2 1 /c with the lattice parameters a = 439.04(9), b = 691.2(2), c = 896.8(2) pm, and β = 90.96(3)°. The structure is isotypic to the high-pressure phase β -HfB 2 O 5 , which is built up from layers of exclusively corner-sharing BO 4 tetrahedra. Between these layers, the cations are coordinated square-antiprismatically by eight oxygen atoms.