THE CRYSTAL-STRUCTURE OF LANTHANUM META-PHOSPHATE LAP3O9

The crystal structure of LaP//3O//9 has been determined by conventional single-crystal X-ray diffraction techniques. The compound is isostructural with NdP//3O//9 and the crystals are orthorhombic. The structure was refined based on 1000 diffractometer collected reflections with I greater than 1. 96 sigma (I). Final agreement factors were: R equals 0. 027 and R//W equals 0. 033. The structure is represented by 'infinite' chains of corner-sharing PO//4 tetrahedra and edge-sharing LaO//8 dodecahedra. Lanthanum-oxygen coordination bond lengths vary from 2. 415(4) to 2. 749(4) angstrom. The closest La-La distance is 4. 315(1) angstrom. No evidence was found for ninefold coordination around La atoms.