Indentation moduli and microhardness of RE-Si-Mg-O-N glasses (RE = Sc, Y, La, Sm, Yb and Lu) with different nitrogen content

The indentation moduli and microhardness of RE-Si-Mg-O-N glasses (RE =
Y, Sc and lanthanides La, Sm, Yb and Lu) containing 20-24 eq.% of
nitrogen were found to depend on RE type and nitrogen content as well.
The Lu-containing glasses were approximately 15-28% harder than
La-glasses with the same nitrogen content and 4% increase in nitrogen
content results in I to similar to10% increase of microhardness. The
effectiveness of the RE elements with regard to their ability to
increase selected mechanical properties of the oxynitride glasses rises
from La, Y/Sc/Sm. to Yb and Lu. The properties studied increase
approximately linearly with cationic field strength (CFS) of the
corresponding lanthanide cation in the glass network. The properties of
Y- and Sc-containing glasses do not follow this dependence. These
changes cannot be explained in terms of CFS and additional effects have
to be considered to characterize relationships between composition,
structure, and properties in the glasses containing non-lanthanide
elements.