The formation of europium–tellurite glasses by the known
sol–gel method was investigated as a function of addition of
Eu(NO3)3 content. The information concerning europium ions
incorporation in tellurite glasses,as provided by the different
techniques employed, are discussed in the following by separately
considering: IR,UV–vis data and DSC investigations.
Our results indicate that by increasing of rare earth ions
concentration in the matrix network,then umber of the[TeO3]
trigonal pyramidal units and non-bridging oxygen ions increase.
Tellurium atoms have the ability to change valence state and
produce structural voids around it.Further europium ions will be
in corporated in the network near to such defects.Then, partial
replacements of Te–O covalent bonds by Eu–O ionic bonds induce
global weakening of the network and decreasing of the crystal-
lization and glass transition temperatures.
The increase in the intensity of theUV–vis absorption bands
situated between 320 and 600 nm strongly depends on the
chemical environment where the europium ionis located and
the number of the non-bridging oxygen ions Table1.