CRYSTAL-STRUCTURE REFINEMENT OF LITHIOPHORITE

A single-crystal X-ray diffraction study of lithiophorite [(Al,Li)MnO2 (OH)2] revealed that the structure is trigonal (R3mBAR), not monoclini c as previously reported, and yielded unit-cell parameters a = 2.9247( 4), c = 28.169(6) angstrom. The study confirmed that the structure con sists of alternately stacked layers of Mn-0 and (Al,Li)-OH octahedra. The refinement successfully revealed the H atom position. Structure en ergy calculations were used to assess the effects of various Al-Li ord ering schemes on the H atom position. Precession photographs show weak superstructure reflections, corresponding to a primitive trigonal uni t cell with a = 5.056 and c = 56.34 angstrom.