Structural and thermochemical study of Na2O-ZnO-P2O5 glasses

Refka Oueslati Omrani (1) , Saida Krimi (2) , Jean-Jacques Videau (3) , Ismail Khattech (1) , Abdelaziz El Jazouli (4) , Mohamed Jemal (1)

1 LR01S10 - Laboratoire de Thermodynamique Appliquée
2 Laboratoire de Physico-Chimie des Matériaux Inorganiques
3 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
4 Laboratoire de Chimie des Matériaux Solides

Glasses of the (50 − x/2)Na2O-xZnO-(50 − x/2)P2O5(3 ≤ O/P ≤ 3.49) and (50 − x)Na2O-xZnO-50P2O5 (O/P = 3) (0 ≤ x ≤ 33 mol%) compositions were prepared using the conventional melt quenching technique. The increase of density and glass transition temperature in both series is related to the reticulation of phosphate chains. For the first series of glasses, Fourier-transformed infrared (FTIR), Raman and 31P solid state magic angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopy revealed the decrease of Q2 tetrahedral sites and the increase of phosphate dimers (Q1), indicating the shortening of phosphate chains. For the second series, FTIR and Raman spectroscopy show only the presence of Q2 tetrahedral sites. Dissolution of these series in 4.5% weight of H3PO4 solution has been followed calorimetrically and showed that the dissolution of the first series is endothermic for the low ZnO content and becomes exothermic when x rises. This behavior is correlated to the structural modification. For the second series, the dissolution phenomenon is endothermic confirming the presence of the same structure over the whole composition range.

Mots clés: Phosphate glasses; Depolymerization; Calorimetric study; Heat dissolution

Domaines: Matériaux

Refka Oueslati Omrani, Saida Krimi, Jean-Jacques Videau, Ismail Khattech, Abdelaziz El Jazouli, et al.. Structural and thermochemical study of Na2O-ZnO-P2O5 glasses. Journal of Non-Crystalline Solids, 2014, 390, pp.5-12. ⟨10.1016/j.jnoncrysol.2014.02.020⟩. ⟨hal-00975104⟩