Physical properties and MAS-NMR studies of titanium phosphate-based glasses (original) (raw)
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Acta Biomaterialia, 2012
Phosphate-based glasses have been investigated for tissue engineering applications. This study details the properties and structural characterization of titanium ultra-phosphate glasses in the 55(P(2)O(5))-30(CaO)-(25-x)(Na(2)O)-x(TiO(2)) (0≤x≤5) system, which have been prepared via melt-quenching techniques. Structural characterization was achieved by a combination of X-ray diffraction (XRD), and solid-state nuclear magnetic resonance, Raman and Fourier transform infrared spectroscopies. Physical properties were also investigated using density, degradation and ion release studies; additionally, differential thermal analysis was used for thermal analysis of these glasses. The results show that with the addition of TiO(2) the density and glass transition temperature increased whereas the degradation and ion release properties are decreased. From XRD data, TiP(2)O(7) and CaP(2)O(6) were detected in 3 and 5 mol.% TiO(2)-containing glasses. Magic angle spinning nuclear magnetic resonance results confirmed that as TiO(2) is incorporated into the glass; the amount of Q(3) increases as the amount of Q(2) consequently decreases, indicating increasing polymerization of the phosphate network. Spectroscopy results also showed that the local structure of glasses changes with increasing TiO(2) content. As TiO(2) is incorporated into the glass, the phosphate connectivity increases, indicating that the addition of TiO(2) content correlates unequivocally with an increase in glass stability.
Preparation and Characterization of Phosphate Glasses Containing Titanium
2007
A b s t r a c t Clear bubble-free phosphate glasses, having composition 40Na 2 O-10Al 2 O 3 -xTiO 2 -(50-x)P 2 O 5 , (x = 0-20 mol %), were prepared by conventional melt quench method. Density, molar volume, glass transition temperature (Tg), MicroHardness (MH), and Thermal Expansion Coefficient (TEC) were measured as a function of TiO 2 content. Structural investigation was done using Raman and FTIR spectroscopy. Substitution of TiO 2 for P 2 O 5 up to 10 mol %, in the ternary 40Na 2 O-10Al 2 O 3 -50P 2 O 5 glass increases the density, Tg and MH. Above the 10 mol % TiO 2 content, all these properties show a reverse trend. Spectroscopic investigations reveal the depolymerization of the phosphate glass network by systematic conversion of Q 2 structural units into Q 1 and finally into Q 0 structural units. Even though Q 2 to Q 1 conversion is taking place due to breaking of P-O-P linkages, formation of P-O-Ti and P-O-Al linkages provide cross linking between short P-structural units, ...
IOP Conference Series: Materials Science and Engineering, 2016
The possibility of producing phosphate based glasses (PBG) with tailored degradation profile allows for unique utilisation in biomedical application. Various compositions in the phosphate based glass (PBG) system of (50-x)P2O5-40Ca-(5+x)Na-5TiO2 and (50-x)P2O5-40Ca-(5+x)Na-5Fe2O3, where x= 5 and 10 were prepared and characterised. Method as differential scanning calorimetry (DSC) has been used to characterise the thermal properties of these phosphate based glasses. It was observed that both glass transition temperature (Tg) and onset of crystalisatisation temperature (Tx) increased with increasing phosphate content. In addition, Tg values were found to be higher for the P2O5-CaO-Na2O-TiO2 glass system compared to P2O5-CaO-Na2O-Fe2O3 glass system. The density result showed that increasing the P2O5 content at the expense Na2O led to a decrease in density for both glass systems. The dissolution study of these glasses was conducted in phosphate buffered saline (PBS). It was observed that the dissolution rate of P2O5-CaO-Na2O-Fe2O3 glass system was higher than the P2O5-CaO-Na2O-TiO2 glass system. The dissolution rate for both glass systems was in the order of 10-6 g cm-2 hr-1 .
Structural characterization of TiO2–P2O5–CaO glasses by spectroscopy
Journal of the European Ceramic Society, 2010
The structure of glasses with composition x TiO 2 •(65 − x) P 2 O 5 •35 CaO (x = 0-30 mol%) has been studied and their glass transition temperature, Raman and NMR spectra have been analysed. For TiO 2-free glass two phosphate species have been identified as Q 2 and Q 3. Increasing TiO 2 content in glass compositions results in the disappearance of the Q 3 and Q 2 species and in the formation of, mainly, pyrophosphate structure, Q 1. In calcium titanophosphate glass with higher TiO 2 content the structure consists of a distorted Ti octahedral linked to pyrophosphate unit through P-O-Ti bonds. In these glass series the structural cohesion increases with TiO 2 , although a depolymerization in the original P-O-P network occurs. The study of these glasses and the understanding of their structural characteristics can give a valuable contribution for the clarification of their degradation behaviour namely in biological environments.
Journal of Biomedical Materials Research Part B: Applied Biomaterials, 2019
Varying formulations in the glass system of 40P2O5-(24-x)MgO-(16+x)CaO-(20-y)Na2O-yTiO2 (where 0≤x≤22 and y=0 or 1) were prepared via melt-quenching. The structure of the glasses was confirmed by X-ray diffraction (XRD), Fourier transform infrared (FTIR), micro Raman and solid-state nuclear magnetic resonance (NMR) spectroscopies. The thermal properties and the activation energy of crystallisation (Ec) were measured using thermal analysis and the Kissinger equation, respectively. The glass forming ability of the formulations investigated was seen to decrease with reducing MgO content down to 8 mol% and the glass stability region also decreased from 106 o C to 90 o C with decreasing MgO content. The activation energy of crystallisation (Ec) values also decreased from 248 (for 24 mol% MgO glass) to 229 2 kJ/mol (for the 8 mol% MgO content) with the replacement of MgO by CaO for glasses with no TiO2. The formulations containing less than 8 mol% MgO without TiO2 showed a strong tendency towards crystallisation. However, the addition of 1 mol% TiO2 in place of Na2O for these glasses with less than 8 mol% MgO content, inhibited their crystallisation tendency. Glasses containing 8 mol% MgO with 1 mol% TiO2 revealed a 12 o C higher glass transition temperature, a 14 o C increase in glass stability against crystallisation and a 38 kJ/mol increase in Ec in comparison to their non TiO2 containing counterpart. NMR spectroscopy revealed that all of the formulations contained almost equal percentages of Q 1 and Q 2 species. However, FTIR and Raman spectroscopies showed that the local structure of the glasses had been altered with addition of 1 mol% TiO2, which acted as a network modifier, impeding crystallisation by increasing the cross-linking between phosphate chains and consequently leading to increased Ec as well as their glass forming ability.
Study of structural modification of sodium aluminophosphate glasses with TiO 2 addition through Raman and NMR spectroscopy, Physica B (2008), Abstract Structural modification of sodium aluminophosphate glasses with TiO 2 addition has been investigated using Raman and MAS-NMR ( 31 P & 27 Al) spectroscopy. TiO 2 incorporated sodium aluminophosphate glasses having composition (mol %): 40Na 2 O-10Al 2 O 3 -xTiO 2 -(50x)P 2 O 5 (x = 0-20), are prepared by conventional melt quench method. The low frequency Raman spectrum suggests an increase in the average ionic character of phosphate glass network with addition of TiO 2 . Raman and 31 P MAS-NMR revealed that the glasses without TiO 2 , consist mainly metaphosphate (Q 2 ) structural units. These are gradually converted into pyrophosphate (Q 1 ) and orthophosphate (Q 0 ) structural units along with the formation of P-O-Ti/P-O-Al linkages. 27 Al MAS-NMR revealed the change in coordination of Al from octahedral (AlO 6 ) to tetrahedral (AlO 4 ) for TiO 2 above 10 mol %. Raman spectra indicate that TiO 2 enters the network in the form of octahedral (TiO 6 ) and tetrahedral (TiO 4 ) structural units and at high concentration of TiO 2 , tetrahedral structural units are more favourable.
Elaboration and structural characterization of phosphate glasses with composition 37.5Na2O-25[(1-x)MgO-xNiO]-37.5P2O5 (0≤x≤1), 2019
Phosphate glasses, with molar compositions 37.5Na2O-25[(1-x)MgO-xNiO]-37.5P2O5 (0 ≤ x ≤ 1), have been prepared using the conventional melt quenching technique. The free nickel glass is colorless while the glasses containing nickel are yellow. The effect of Ni 2+ ions on structural and physico-chemical properties of these glasses has been investigated by XRD, DTA, EPR, Raman, FTIR spectroscopies and by density and chemical durability measurements. Substitution of Ni 2+ for Mg 2+ strengthens the glass network, as shown by the decrease of the molar volume, the increase of the glass transition temperature, and the improvement of the chemical durability. This behavior is a consequence of the replacement of Mg-O bonds by more covalent Ni-O bonds. The glass structure consists of tri-phosphate (P3O10) 5-and di-phosphate (P2O7) 4-groups, and Mg/NiO6 octahedra, with Mg-O-P and Ni-O-P linkages.
Advances in Materials Physics and Chemistry, 2020
Phosphate glasses of composition 48P2O5-30CaO-(22−x)Na2O-xTiO2 (with 0 °C ± 20°C. The chemical durability of these glasses shows an improvement when the TiO2 content varies from 0 to 2 mol%. The measurements of differential thermal analysis and density, both, indicate the increase of the glass transition temperature and the density. The increase of Tg leads to an improvement of glass rigidity. X-ray diffraction analysis of the glasses annealed at 650°C for 48 h, indicates the appearance of a mixture of metaphosphate and pyrophosphate phases when the TiO2 content varies from 0 to 2 mol%, the last become majority when the TiO2 content rich 2 mol%. Nevertheless, when the TiO2 content exceeds 2 mol%, the analysis, both, by infrared spectroscopy and X-ray diffraction, reveals a radical change of structure with the formation of majorities isolated orthophosphate groups. SEM micrographs illustrated that the number of crystallites increased in the glass network when the TiO2 content increas...
Effect of TiO 2 on the chemical durability and optical properties of Mo-based phosphate glasses
The phosphate glasses belonging to the 20Li 2 O− (40− x)Li 2 MoO 4 − xTiO 2 − 40P 2 O 5 (0≤x≤10 mol%) system were prepared via melt quenching route at 900 ±15 • C. The prepared samples are characterized by X− Ray diffraction and differential scanning calorimetry to check possible crystalline residues and the glassy state. The structural properties of these glasses were investigated by some physical parameters such as density, molar volume, and glass transition temperature (T g). Density values, molar volume values, and T g values were found to depend strongly on the chemical composition of the glasses. The density decreased from 3.68 ±0.01 g/cm 3 to 3.27 ±0.01 g/cm 3 , and T g increased from 372 ±2 • C to 407 ±2 • C with the TiO 2 content increased from 0 mol% to 10 mol%. The structural approach is verified by Infrared (IR) and Raman spectroscopies. The chemical durability tests on the glasses have shown that the compositions containing pyrophosphate (Q 1) and orthophosphate (Q 0) units are more water− resistant. The optical properties have been evaluated by determining some parameters, like optical band gap energy (E g) and Urbach energy (ΔЕ) and their values are determinate. These parameters vary in opposite; E g decreased from 2.12 eV to 1.35 eV and ΔЕ increased from 0.38 eV to 0.48 eV with increasing in TiO 2 mol %.
Journal of Biomaterials Applications, 2005
This article reports on the use of ion chromatography (IC) to investigate extensively the release profiles of both cations and anions and characterize the relationship between composition and degradation for a ternary-based Na 2 O-CaO-P 2 O 5 glass system developed as biomaterials. Studies are carried out on glasses with the formula 45P 2 O 5-55(xCaO-Na 2 O) in deionized water, where x ¼ 30, 35, and 40 mol%, using a cumulative release method, where the solution is changed at regular intervals. Degradation behavior is linear with time where the degradation rate shows an initial decrease with increasing CaO content. This rate then increases with a further addition of CaO. Cation release profiles follow similar trends to the degradation rates. Anion release profiles show a decrease for the PO 4 and linear polyphosphate (P 2 O 7 and P 3 O 10) species with increasing CaO content. This decrease is attributed to the cross-linking of the Ca 2þ ions. In contrast, the cyclic P 3 O 9 anion exhibits the highest amount of anionic release, which demonstrates similar trends to the cations. These release patterns suggest that the cyclic P 3 O 9 species dominate the degradation rates. The proposed mode of degradation is a hydrolysis reaction, with the cyclic metaphosphate undergoing acid/ base catalysis. The pH remains constant for the 30 and 35 mol% CaO glasses, and drops to about 5.5 for the 40 mol% composition. By using a response factor,