Synthesis and crystal structure of the praseodymium orthoborate λ -PrBO_3

摘要

The praseodymium orthoborate λ -PrBO_3 was synthesized from Pr_6O_(11), B_2O_3, and PrF _3 under high-pressure / high-temperature conditions of 3 GPa and 800 °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 title compound crystallizes in the orthorhombic aragonite-type structure, space group Pnma, with the lattice parameters a = 577.1(2), b = 506.7(2), c = 813.3(2) pm, and V = 0.2378(2) nm~3, with R1 = 0.0400 and wR2 = 0.0495 (all data). Within the trigonal-planar BO _3 groups, the average B-O distance is 137.2 pm. The praseodymium atoms are ninefold coordinated by oxygen atoms.