Structural Role of Nd2O3 as Dopant Material in Modified Borate Glasses and Glass Ceramics

Glasses in the system xNd2O3–(46 − x)B2O3–27CaO–24.4Na2O–2.6 P2O5 (0 ≤ x ≤ 4 mol%) have been prepared via conventional melt quenching technique. X-ray diffraction spectra have showed that the amorphous structure is dominant in glasses of Nd2O3 concentrations ≤ 0.5 mol%. But formation of a more ordered structure is confirmed at higher Nd2O3 values. Result based on differential scanning calorimetry shows an increase in glass transition temperature (Tg) with increasing Nd2O3 at expense of B2O3. The measured density is found to be increased whereas the molar volume is decreased with increasing Nd2O3 content. The calculated molar volume (Vm) and free spaces (Vf) are both decreased due to filling process which is suggested to be carried out by Nd3+ of larger size than that of B3+. Decreasing of Vm and Vf can reflect the increase in bridging bonds in the glass network which in turns results in increasing of Tg of the investigated compositions. The thermal heat treatment process has no effect on state of crystal formation in glass containing 4 mol% Nd2O3.