Thermal expansion and glass transition temperature of the rare-earth doped oxynitride glasses

Thermal expansion coefficients (alpha), glass-transition (T-g) and
Littleton (T-L) temperatures, hardness and density of the RE-Si-Mg-O-N
glasses (RE = Se, Y, La, Nd, Sm, Gd, Yb, and Lu) were investigated to
separate the effects of rare-earth elements and nitrogen on the
properties of bulk glasses. These properties depend approximately
linearly on nitrogen content, density of the glass and ionic radius of
the corresponding lanthanide. Lanthanides modify hardness of the
studied oxynitride glasses with 20-24 eq.% N by 11.4-14.4%, alpha by
similar to13%, T-g by 31-35 degreesC, and T-L by 33-43 degreesC.
Deviations from linearity found in Nd-, Sm- and Yb-doped glasses were
possibly due to valence change. Non-lanthanide dopants, Sc and Y, often
do not fit the dependence but result in comparable properties. The
effects of nitrogen and rare-earth dopants are independent and
additive.