On the crystal structure of the manganese(III) trioxides of the heavy lanthanides and yttrium

Abstract

The preparation, determination of optical properties, and approximate crystal structure of the ferro-electric manganese (III) trioxides of holmium, erbium, thulium, ytterbium, lutetium, and yttrium are reported. The compounds crystallize in the hexagonal system, probable space group P6acm , and their structure is characterized by unusual five-and sevenfold coordination polyhedra about manganese and rare-earth atoms respectively. The unacceptable values assumed by the temperature factors of two oxygen ions throw doubt on the exact determination of atom positions by least-squares refinement. Possible causes of this difficulty are reviewed.