TITLE:
Structural Features and Properties of the Vitreous Part of the System 50P2O5-25CaO-(25-x)Na2O-xCoO (with 0 ≤ x ≤ 25; mol%)
AUTHORS:
Brahim Bachachir, Yassine Er-Rouissi, Radouane Makhlouk, Achraf Harrati, Abdeslam El Bouari, Said Aqdim
KEYWORDS:
Chemical Durability Phosphate Glasses, Cobalt Oxide, Density, DTA, DRX, IR, SEM Micrograph
JOURNAL NAME:
Advances in Materials Physics and Chemistry,
Vol.11 No.12,
December
29,
2021
ABSTRACT: The glass series 50P2O5-25CaO-(25-x)Na2O-xCoO (with (0 ≤ x ≤ 25; mol%), has been prepared by direct melting at 1080°C ± 20°C. The introduction of cobalt in calcium phosphate glasses is usedto compare its effect with calcium in inhibition corrosion. The dissolution rate has been investigated. It indicated an improvement of chemical durability when the cobalt oxide increases in the network glass at the expense of Na2O content. Both, IR spectroscopy and X-ray diffraction have confirmed the structure changes when the CoO content increases in the glass. This change results in the disappearance of isolated orthophosphate groups followed of a polymerizing of the structure from isolated orthophosphate towards pyrophosphate chains (Q1) by promotingthe formation of olygophosphates (mixed Q1-Q2) rich in pyrophosphates. Analysis of the density values, showed an increase of density with the increase CoO content. The covalent radius values of oxygen rcal (O2-) indicate a significant decrease and therefore a relatively high reinforcement of the metal-oxygen-phosphorus (Co-O-P) bonds. SEM micrograph confirms the evolution of the glass structural morphology. The sample having a maximum CoO content confirms a homogeneous glass phase with quite crystalline particles. This property is prerequisite for many interesting industrial applications.