CRYSTAL-STRUCTURES OF THE HIGH-TEMPERATURE FORMS OF LN(2)SI(2)O(7) (LN=LA, CE, PR, ND, SM) REVISITED


TAS A., AKINC M.

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, cilt.77, sa.11, ss.2968-2970, 1994 (SCI-Expanded) identifier identifier

Özet

The crystal structures of the high-temperature forms of light lanthanide pyrosilicates (disilicates), i.e., (La-to-Sm)(2)Si2O7, have been studied with powder X-ray diffraction on the quenched samples. These compounds have monoclinic structures with the space group P2(1)/n rather than orthorhombic structures. In the research of the last two decades, the smallness of the monoclinic angles (90.1 degrees-91 degrees) has possibly obscured the revelation of the true structural nature of these compounds. New XRD patterns are suggested for the studied lanthanide pyrosilicates exhibiting the monoclinic characteristics of the unit cells.