Revised Structure of the Orthoborate YBO3

The YBO3orthoborate was prepared by a flux evaporation process and the diffraction lines of its X-ray pattern were indexed on the basis of single crystal data. Crystal structure was determined (R=0.035) in theP63/mspace group from data recorded on a four-circle automatic diffractometer, with cell parametersa=3.776 (1) Å,c=8.806 (4) Å. The structure consists of a three-dimensional network made up of eightfold coordinated yttrium atoms and fourfold coordinated boron atoms. The structure exhibits two nonequivalent environments for the yttrium ions, which is confirmed by luminescence studies using the Eu3+ion as structural probe. This work was completed by11B NMR and IR studies, which show that boron has tetrahedral coordination.