Structural and Calorimetric Studies of Zinc, Magnesium and Manganese Based Phosphate and Phosphate-Silicate Glasses

Glasses of the (50-x/2)Na2O-xMO-(50-x/2)P2O5 (M = Zn, Mg or Mn) (0 ≤ x ≤ 33 mol%), (50-x)Na2O-xMO-50P2O5 (M = Zn, Mn) (0 ≤ x ≤ 33 mol%), and (0.9-x)NaPO3-xSiO2-0.1ZnO (0 ≤ x ≤ 0.1 mol) were prepared by the melt quenching technique. Samples were investigated by means of X-ray diffraction, Archimede’s method, ellipsometry, Fourier-transformed infrared (FTIR), Raman, 31P solid state magic angle spinning nuclear magnetic resonance (MAS-NMR), UV-visible spectroscopy and calorimetry. For zinc, manganese and magnesium phosphate glasses, the increase in density with the addition of MO oxide suggests the compactness of the vitreous network. For zinc phosphate silicate glasses, the variations of density and refractive index were attributed to the structural changes when SiO2 oxide is progressively introduced. The increase in the glass transition temperature (Tg) reflects an increase in the cross-link strength of the structure as MO and SiO2 oxides are gradually incorporated. For all glass composition, spectroscopic investigations revealed the depolymerization of metaphosphate chains (Q2) allowing the formation of phosphate dimers (Q1). Calorimetric dissolution shows that the dissolution is endothermic for lower MO content and become exothermic when x rises. For (50-x/2)Na2O-xZnO-(50-x/2)P2O5 (0 ≤ x ≤ 33 mol%) glasses, the formation enthalpy increases with the incorporation of ZnO oxide

Structure properties relationship in calcium sodium metaphosphate and polyphosphate glasses

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Effect of SrO content on the structure and properties of sodium-strontium metaphosphate glasses

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Structural investigations and calorimetric dissolution of manganese phosphate glasses

Two series of manganese phosphate glasses (50x/2)Na2O-xMnO-(50 − x/2)P2O5 and (50 − x)Na2O-xMnO-50P2O5 (0 ≤ x ≤ 33 mol%), were prepared and investigated by means of density measurements, molar volume evolutions, FTIR and Raman spectroscopy, differential scanning calorimetry and calorimetric dissolution. In both series, density and glass transition temperature increase with composition. For the first series of glasses (3 ≤ O/P ≤ 3.49), spectroscopic analysis indicates that the addition of MnO content induces an evolution of structural units from Q2 to Q1 tetrahedral sites indicating the depolymerization of phosphate chains. By introducing MnO oxide into the second glass series (O/P = 3), Psingle bondOsingle bondP linkages are disrupted, suggesting a structural changes in the vitreous network. Calorimetric dissolution of both series of glasses in 4.5% weight of H3PO4 solution shows that the dissolution phenomenon is endothermic for the low MnO content and becomes exothermic as MnO concentration increases. This behavior may be correlated to the structural modification resulted from the depolymerization of the infinite metaphosphate chains

Structure and thermochemical study of strontium sodium phosphate glasses

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Structural and thermochemical study of Na2O-ZnO-P2O5 glasses

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

Structural characterization and calorimetric dissolution behavior of Na2O-CuO-P2O5 glasses

Two series of glasses belonging to the ternary system Na2O - CuO - P2O5 where copper is introduced differently were synthesized by the conventional melt-quenching technique. Both series start from meta-phosphate composition NaPO3 (50Na2O-50P2O5). In the first series, the Na2O/P2O5 ratio is constant (Na2O/P2O5 = 1) and both Na2O and P2O5 oxides were replaced by copper oxide CuO: (50-x/2) Na2O - xCuO - (50-x/2) P2O5, 0 ≤ x ≤ 40. In the second series, the molar percentage of P2O5 is kept constant at 50 mol% and Na2O is replaced by CuO: (50-x)Na2O – xCuO – 50P2O5, 0 ≤ x ≤ 50. The glasses of these two series belong respectively to NaPO3-CuO and NaPO3-Cu(PO3)2 lines of the ternary system. These materials were characterized by density measurements, differential scanning calorimetry (DSC), X-ray diffraction (XRD), Raman, diffuse reflectance and dissolution heat measurements carried out with micro-calorimetry technique. Introduction of copper in meta-phosphate glass induces a blue/green color, and strengthens the vitreous network, as shown by the decrease of the molar volume (VM) and the increase of the glass transition temperature (Tg) when the content of CuO rises. The crystallization of the glasses, followed by XRD, leads to the formation of NaPO3, Na2CuP2O7 or Na2Cu(PO3)4 depending on the composition. Raman spectroscopy shows the conservation of the metaphosphate chains for NaPO3-Cu(PO3)2 glasses characterized by a constant O/P ratio (O/P = 3) and the depolymerization of these chains for NaPO3-CuO glasses where O/P ratio varies from 0 to 3.67. UV - visible study showed that the optical energy gap decreases by increasing the CuO concentration. Calorimetric study of the dissolution of glasses in acid solution shows a decrease of the dissolution enthalpy, for both series, when the CuO content increases. The dissolution phenomenon is endothermic for glasses with low content in CuO (x < 30) and exothermic for glasses rich in CuO

Structural and thermochemical properties of sodium magnesium phosphate glasses

Ternary phosphate based glasses with the general formula (50−x/2)Na2O–xMgO–(50−x/2)P2O5 (0 ⩽ x ⩽ 42.8 mol%), where the O/P ratio was varied from 3 to 3.75, have been prepared using a conventional melt quenching technique. Samples were investigated by means of density measurements, Fourier-transformed infrared (FTIR), Raman and 31P solid state magic angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopies, differential scanning calorimetry (DSC), inductively coupled plasma atomic emission spectroscopy (ICP/AES) analysis and calorimetric dissolution.The depolymerization of metaphosphate chains are described by the decrease of Q2 tetrahedral sites allowing the formation of pyrophosphate groups (Q1) revealed by spectroscopic investigations. As a result, the increase of density and glass transition temperature when x rises. Calorimetric study shows that the dissolution phenomenon is endothermic for a lower MgO content and becomes exothermic when magnesium oxide is gradually incorporated, suggesting the disruption of phosphate chains with increasing O/P ratio