Results from full profile analysis of powder neutron diffraction patterns (lambda = 1.05 Angstrom and lambda = 2.475 Angstrom) taken at room temperature are presented. The refinements in space group R (3) over bar yielded considerably better reliability factors than those obtained in group R (3) over bar m as suggested in previous X-ray diffraction works. (C) 2000 Elsevier Science B.V. All rights reserved.