The microstructure of thermally treated neodymium containing silica ge
ls is investigated by transmission electron microscopy and electron di
ffraction. Microheterogeneities with amorphous nature are found. Infor
mation for the short range order is obtained by the Radial Distributio
n Functions: SiO4 tetrahedra and NdO6 groups are formed and transition
from four-fold to six-fold ring structure is observed with increasing
of the heat treatment temperature.