Thermal, elastic and dielectric properties of rare-earth containing oxynitride glasses

Thermal expansion coefficients (alpha), glass-transition (T-g) and
softening (T-L) temperatures, elastic moduli, dielectric constants
(epsilon) and dielectric losses (tan delta) of bulk RE-Si-Mg-O-N
glasses (RE = Sc, Y, La, Nd, Sm, Gd, Yb, and Lu) with different
nitrogen contents were investigated to evaluate the compositional
effects. Lanthanides modify a. of the studied oxynitride glasses with
20 and 24 eq.% N by similar to12%, T-g by 32-38degreesC, Young's
modulus from 130 to 150 GPa (similar to13%), epsilon from 13.1 to 11
(similar to19%) and tan delta from 0.003 to 0.001. These properties
depend approximately linearly on nitrogen content and glass density,
but with different slopes for lanthanides and for Sc, Y and La group.
Density changes were found to result from the atomic weight of the
corresponding RE rather than from network tightening due to the
dependence on RE ionic size. In contrast, nitrogen causes only small
density increase but significant tightening of glass network and more
effective changes of the studied properties than RE additives. The
mechanisms in which non-lanthanide additives affect glass properties
... mehr
may be different from that of lanthanide modifiers.