Abstract

Two different monoclinic structures have been found in rare earth oxyorthosilicates: the first (La…Tb) has the space group P2₁/c and contains 9 and 7 coordinated cations, the second (Dy…Lu) has the space group B2/c and also has two different cation sites with coordination numbers 6 and 7 (1). The literature concerning La₂(SiO₄)O is contradictory and it seems that lanthanum does not belong to the first structure group but has an unknown structure of its own (2). The literature of rare earth silicate phosphors is limited and is mostly patented.

© 1984 Optical Society of America