A new type of cerium borate glass-ceramic is prepared and studied. The microstructure and crystallization behaviors of the glass samples were investigated by X-ray diffraction (XRD), electron diffraction (ED), and <...A new type of cerium borate glass-ceramic is prepared and studied. The microstructure and crystallization behaviors of the glass samples were investigated by X-ray diffraction (XRD), electron diffraction (ED), and <sup><span style="font-size:12px;font-family:Verdana;">31</span></sup><span style="font-family:Verdana;">P NMR spectroscopy. The microstructures of samples contain <1 mol% CeO</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">are amorphous in nature. More addition of CeO</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> transforms the glass to glass-ceramics without thermal annealing. The morphological change of the microstructure of these materials was followed by transmission electron microscopy (TEM). The obtained results have revealed that the addition of more than 0.8 mol% CeO</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> can promote nucleation and crystallization routes that </span></span><span style="font-family:Verdana;">are </span><span style="font-family:;" "=""><span style="font-family:Verdana;">combined with the establishment of diverse crystalline phases. Glasses with lower contents of CeO</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">showed no tendency to crystallization. The crystals of CeO</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> containing glasses were spheroid like morphology that </span></span><span style="font-family:Verdana;">was </span><span style="font-family:Verdana;">assigned to the three-dimensional fast growth of the well-formed structural species in the boro-apatite phase. In addition, the cerium free glass is characterized by particle-like morphology. Then the growth of spheroid species in three-dimension plays better compatibility and bioactivity behavior than that of the other types of morphology. This is may because the spherical shape has a higher surface area than that of the needle-like morphology. Accumulation and aggregation of small-sized spheres from cerium borate phases played the role of enhancing the hardness of the studied materials.</span>展开更多
The structure of glasses in the system of xCeO2(100?-?x)B2O3, x = 30, 40, 50 mol% CeO2 has been explored for the first time by correlation between data obtained from XRD, FTIR and 11B NMR analyses. NMR spectroscopy an...The structure of glasses in the system of xCeO2(100?-?x)B2O3, x = 30, 40, 50 mol% CeO2 has been explored for the first time by correlation between data obtained from XRD, FTIR and 11B NMR analyses. NMR spectroscopy andFTIR spectroscopy have confirmed that transformation rate of BO3 to BO4 groups is reduced by CeO2 addition.The concentration of Ce4-O-Ce4 is increased at the expense of both B4-O-Ce4 and B3-O-B4 linkages. Boron atoms are mainly coordinated with Ce4 sites as second neighbors due to increasing CeO4 species with further increase of CeO2 concentration. Increasing B4 fraction is considered due to forming of CeO4 with rate higher than that of BO4 units. The change of chemical shift of 11B nuclei upon exchanging B2O3 with CeO2 confirms that the central boron atoms would be coordinated with tetrahedral cerium atoms as second neighbors. The X-ray diffraction of cerium rich glass is clearly indicated that the formation of crystalline phases refers to CeO4, CeBO3and Ce(BO2)3 species.展开更多
Glasses and glass ceramics in the system xCeO<sub>2·</sub>(50 - x)PbO·50B<sub>2</sub>O<sub>3</sub> (0 ≤ x ≤ 50) have been studied, for the first time, by NMR a...Glasses and glass ceramics in the system xCeO<sub>2·</sub>(50 - x)PbO·50B<sub>2</sub>O<sub>3</sub> (0 ≤ x ≤ 50) have been studied, for the first time, by NMR and FTIR techniques. Effect of CeO<sub>2</sub> substitution with PbO on NMR parameters has been discussed in terms of changing both boron and cerium coordination. The quantitative fraction of four coordinated boron (N<sub>4</sub>) has been simply determined from <sup>11</sup>B NMR spectroscopy. On the other hand, the fraction of total tetrahedral structural units B<sub>4</sub> (BO<sub>4</sub> + PbO<sub>4</sub> + CeO<sub>4</sub>) is obtained from FTIR spectral analysis. It is not possible to get the fraction of cerium oxide directly from the applied spectroscopic tools. Therefore, a simple approach is applied, for the first time, to determine CeO<sub>4</sub> fraction by using the different criteria of both <sup>11</sup>B NMR and FTIR spectroscopy. The fraction of B<sub>4</sub> species is equal to N<sub>4</sub>, within the experimental error, of the same glasses in the composition region of up to 10 mol% CeO<sub>2</sub>. On the other hand, there is a clear difference between both N<sub>4</sub> and B<sub>4</sub> values in glasses of higher CeO<sub>2 </sub>content (>10 mol%). The related difference showed a linear increasing trend with increasing the content of CeO<sub>2</sub> in the glass. This was discussed on the bases of structural role of CeO<sub>2</sub> which acts as a glass former in the region >10 mol%, while, at lower concentration, it consumed as a glass modifier.展开更多
The structure of borosilicate glasses of composition 30Na<sub>2</sub>O-2Al<sub>2</sub>O<sub>3</sub>-25SiO<sub>2</sub>-xFe<sub>2</sub>O<sub>3</sub>...The structure of borosilicate glasses of composition 30Na<sub>2</sub>O-2Al<sub>2</sub>O<sub>3</sub>-25SiO<sub>2</sub>-xFe<sub>2</sub>O<sub>3</sub><sub></sub> (43-x) B<sub>2</sub>O<sub>3</sub> has been investigated in the composition range of 0.5 20 mol% Fe<sub>2</sub>O<sub>3</sub>. <sup>27</sup>Al, <sup>11</sup>B, <sup>29 </sup>Si MAS NMR and FTIR spectroscopies have been used to measure the fraction of different structural species in the glasses. It is evidenced from NMR data that both sodium and Fe<sub>2</sub>O<sub>3</sub> (in low region up to 7 mol%) are the main glass modifier. Structural determination for borosilicate glasses with a high content of (Fe<sub>2</sub>O<sub>3</sub>) was carried out by FTIR spectroscopy, where both <sup>11</sup>B and <sup>29</sup>Si MAS NMR are impossible because of the high quantities of paramagnetic iron (III) species present. NMR analysis was performed on borosilicate glasses containing up to 7 mol% Fe<sub>2</sub>O<sub>3</sub> and the N<sub>4</sub> values obtained by FTIR spectroscopy agree within error with the <sup>11</sup>B NMR results of the same glass samples. Fe<sub>2</sub>O<sub>3</sub> is a main glass modifier in the low-Fe<sub>2</sub>O<sub>3</sub>-content region (≤6 mol%). On other hand, it plays the role of glass former at higher content of Fe<sub>2</sub>O<sub>3</sub>. Increasing both N<sub>4 </sub>of boron tetrahedral units and chemical shift of silicon nuclei to reach maxima at 5 mol% Fe<sub>2</sub>O<sub>3</sub> confirms the role of Fe<sub>2</sub>O<sub>3</sub> as a glass modifier in the low composition region. On the other hand, fast decrease in N<sub>4</sub> with further increasing Fe<sub>2</sub>O<sub>3</sub> contents ≥6 mol%) is an evidence for iron oxide to inter the glass network as a network former.展开更多
Borosilicate glasses and glass ceramics in the system 30Na2O-2Al2O3-25SiO2-xFe2O3(43-x)B2O3 (x = 0 - 20 mol%) have been prepared and studied by distinguished techniques. X-ray diffraction (XRD), transmission electron ...Borosilicate glasses and glass ceramics in the system 30Na2O-2Al2O3-25SiO2-xFe2O3(43-x)B2O3 (x = 0 - 20 mol%) have been prepared and studied by distinguished techniques. X-ray diffraction (XRD), transmission electron microscope (TEM), electron diffraction pattern (EDP) and SEM experiments are applied to explore the induced structural changes. Nanometer-sized species of polycrystalline structure are formed particularly in low Fe2O3 containing glasses. The size of the crystallites is found to depend on Fe2O3 concentrations. It is ranged from 10 to 33 nanometers. Structurally, these materials are suggested to contain different components, crystalline component and an interfacial component which situated between the crystallized domains. Presence of these components affects the atomic arrangement without short- or long-range order. An intermediate range ordered structure is dominant in glass ceramics of Fe2O3 2O3 concentration, since more disordered structure of lower size is present. These structural changes are found to be connected with the role of Fe2O3 and Na2O in glasses. Na2O is the strong glass modifier in the studied composition region, while Fe2O3 is consumed also as a modifier in composition of 2O3 is mainly dominant in the composition region of higher iron oxide concentration (8 - 20 mol%).展开更多
Silver phosphate glasses of general formula xAg2O·(100 - x)P2O5 have been investigated over compositional range from x = 40 to 62.5 mol%. The local structure around phosphorus atom has been studied via 31P nuclea...Silver phosphate glasses of general formula xAg2O·(100 - x)P2O5 have been investigated over compositional range from x = 40 to 62.5 mol%. The local structure around phosphorus atom has been studied via 31P nuclear magnetic resonance. The distribution of [PO4]Qn species as a function of composition has been shown to slightly deviate from the simple binary alkali phosphate model. An anomalous behavior has been recorded and interpreted in terms of mixed ring-chain effect in metaphosphate composition. The splitting of NMR spectra into sub resonances is assigned to different binding sites characterizing Q1 ring and Q1 chain structure. Higher Ag2O concentration (≥50 mol%) leads to formation of phosphate groups with specific resonance peaks which are mainly related to pyro and orthophosphate species. The rate of change of the chemical shift of the 31P NMR depends on the bond type, which in turn reflects the extent of double bonding between phosphorus and oxygen atoms. Increasing concentration of Q0 with increasing Ag2O content leads to decreasing quantities of bridging and double bonds. As a consequence, specific symmetric resonance peak of higher intensity and chemical shift (Q0) is a feature of silver rich glasses (orthophosphate). The latter species is therefore proposed to compose of separated membered rings,?which cause deshielding of phosphate units.?XRD and EDP studies have shown that, amorphous phosphate network is the dominant structure of glasses containing ≤ 55 mol% Ag2O. Some ordered and well crystallized phases are formed at higher Ag2O concentration. Increasing non-bridging oxygen atoms is shown to have the main effect on crystallization behavior. Orthophosphate composition is the most crystalline one among the other compositions (ultra, meta- and pyrophosphate). Presence of orthophosphate species which typically contains highest concentration from isolated Q0 units is the main reason for building up crystalline Ag3PO4phosphate phase.展开更多
Glasses in the system 24.5Na<sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O·24.5CaO·6P</span>...Glasses in the system 24.5Na<sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O·24.5CaO·6P</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O</span><sub><span style="font-size:12px;font-family:Verdana;">5</span></sub><span style="font-family:Verdana;">·xSrO·(45-x)SiO</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> have been</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> studied in the composition region of x = 0 - 15 mol%. The as prepared glasses are transparent and have an amorphous network structure. On the otherhand, heat treated glasses are transformed to opaque white glass ceramic characterized by their highly crystalline network structure. Crystalline apatite (calcium phosphate, Ca</span><sub><span style="font-size:12px;font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">(PO</span><sub><span style="font-size:12px;font-family:Verdana;">4</span></sub><span style="font-family:Verdana;">)</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">, wollastonite (calcium silicate, CaSiO</span><sub><span style="font-size:12px;font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">), and strontium calcium phosphate</span></span><span style="font-family:Verdana;"> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">Ca</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">Sr(PO</span><sub><span style="font-size:12px;font-family:Verdana;">4</span></sub><span style="font-family:Verdana;">)</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> </span></span><span style="font-family:;" "=""><span style="font-family:Verdana;">are the main well-formed crystalline species played the major role in material bioactivity. Increasing SrO leads to enhancing material crystallite and enhances the hardness of the host glass matrix. The change of XRD spectra, </span><sup><span style="font-size:12px;font-family:Verdana;">31</span></sup><span style="font-family:Verdana;">P NMR chemical shift and hardness number upon increasing SrO are considered due to modification of the apatit Ca(PO</span><sub><span style="font-size:12px;font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">)</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> to involve Sr ions inducing Ca</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">Sr (PO</span><sub><span style="font-size:12px;font-family:Verdana;">4</span></sub><span style="font-family:Verdana;">)</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> apatite one. Such species play the role in enhancing material properties and hardness.</span></span>展开更多
Cerium Pyrophosphate glass is prepared and investigated by different structural techniques. Resin modified glass ionomer cements (RGICs) of pyro cerium phosphate (40CeO2-60P2Os) composition doped with different concen...Cerium Pyrophosphate glass is prepared and investigated by different structural techniques. Resin modified glass ionomer cements (RGICs) of pyro cerium phosphate (40CeO2-60P2Os) composition doped with different concentrations from GaCl Phthalocyanine (C32H16ClGaN8) have been also prepared and studied for the first time. Different techniques have been applied to shed?light on the structural changes induced upon addition of GaCl-Phthalocyanine. The corresponding changes in material structure are widely approved by results of 31P magic angle spinning nuclear magnetic resonance (MAS-NMR), X-Ray diffraction and FTIR spectroscopy. The network structure of both base glass and GIC free from C32H16ClGaN8 is confirmed to be amorphous. Doping even with little concentration from GaCl-Phthalocyanine leads to changing the network structure from amorphous to a highly crystalline one. Formulation of GaCl-Phthalocyanine with water soluble acid leads to monocrystalline structure due to monoclinic lattice structure of Phthalocyanine. Carbonated hydroxyl cerium and gallium phosphate structural phases are evidenced to be formed upon GaCl-Phthalocyanine addition. Presence of such bioactive phases can support that the prepared GICs of considerable C32H16ClGaN8 concentration (1 and 1.5 mol%) can be applied as biocompatible materials used in biodental applications. The morphologies of some selected samples were characterized by SEM. The micrographs have revealed that formulating of cerium phosphate powder of the amorphous glass with polymeric acid successfully led to the formation of CePO4-H2O nanofibrous bundles. But formulation with GIC containing GaCl-Phthalocyanine can simply form co-aligned and elongated nanofibers (15 - 40 nm thick and up to ca. 1.2 m long). The formed nanofibers are mainly consisted of hydrated and carbonated CePO4 and GaPO4 nanocrystals. The hardness of the cemented material increases with increasing GaCl-Phthalocyanine concentrations.展开更多
文摘A new type of cerium borate glass-ceramic is prepared and studied. The microstructure and crystallization behaviors of the glass samples were investigated by X-ray diffraction (XRD), electron diffraction (ED), and <sup><span style="font-size:12px;font-family:Verdana;">31</span></sup><span style="font-family:Verdana;">P NMR spectroscopy. The microstructures of samples contain <1 mol% CeO</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">are amorphous in nature. More addition of CeO</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> transforms the glass to glass-ceramics without thermal annealing. The morphological change of the microstructure of these materials was followed by transmission electron microscopy (TEM). The obtained results have revealed that the addition of more than 0.8 mol% CeO</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> can promote nucleation and crystallization routes that </span></span><span style="font-family:Verdana;">are </span><span style="font-family:;" "=""><span style="font-family:Verdana;">combined with the establishment of diverse crystalline phases. Glasses with lower contents of CeO</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">showed no tendency to crystallization. The crystals of CeO</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> containing glasses were spheroid like morphology that </span></span><span style="font-family:Verdana;">was </span><span style="font-family:Verdana;">assigned to the three-dimensional fast growth of the well-formed structural species in the boro-apatite phase. In addition, the cerium free glass is characterized by particle-like morphology. Then the growth of spheroid species in three-dimension plays better compatibility and bioactivity behavior than that of the other types of morphology. This is may because the spherical shape has a higher surface area than that of the needle-like morphology. Accumulation and aggregation of small-sized spheres from cerium borate phases played the role of enhancing the hardness of the studied materials.</span>
文摘The structure of glasses in the system of xCeO2(100?-?x)B2O3, x = 30, 40, 50 mol% CeO2 has been explored for the first time by correlation between data obtained from XRD, FTIR and 11B NMR analyses. NMR spectroscopy andFTIR spectroscopy have confirmed that transformation rate of BO3 to BO4 groups is reduced by CeO2 addition.The concentration of Ce4-O-Ce4 is increased at the expense of both B4-O-Ce4 and B3-O-B4 linkages. Boron atoms are mainly coordinated with Ce4 sites as second neighbors due to increasing CeO4 species with further increase of CeO2 concentration. Increasing B4 fraction is considered due to forming of CeO4 with rate higher than that of BO4 units. The change of chemical shift of 11B nuclei upon exchanging B2O3 with CeO2 confirms that the central boron atoms would be coordinated with tetrahedral cerium atoms as second neighbors. The X-ray diffraction of cerium rich glass is clearly indicated that the formation of crystalline phases refers to CeO4, CeBO3and Ce(BO2)3 species.
文摘Glasses and glass ceramics in the system xCeO<sub>2·</sub>(50 - x)PbO·50B<sub>2</sub>O<sub>3</sub> (0 ≤ x ≤ 50) have been studied, for the first time, by NMR and FTIR techniques. Effect of CeO<sub>2</sub> substitution with PbO on NMR parameters has been discussed in terms of changing both boron and cerium coordination. The quantitative fraction of four coordinated boron (N<sub>4</sub>) has been simply determined from <sup>11</sup>B NMR spectroscopy. On the other hand, the fraction of total tetrahedral structural units B<sub>4</sub> (BO<sub>4</sub> + PbO<sub>4</sub> + CeO<sub>4</sub>) is obtained from FTIR spectral analysis. It is not possible to get the fraction of cerium oxide directly from the applied spectroscopic tools. Therefore, a simple approach is applied, for the first time, to determine CeO<sub>4</sub> fraction by using the different criteria of both <sup>11</sup>B NMR and FTIR spectroscopy. The fraction of B<sub>4</sub> species is equal to N<sub>4</sub>, within the experimental error, of the same glasses in the composition region of up to 10 mol% CeO<sub>2</sub>. On the other hand, there is a clear difference between both N<sub>4</sub> and B<sub>4</sub> values in glasses of higher CeO<sub>2 </sub>content (>10 mol%). The related difference showed a linear increasing trend with increasing the content of CeO<sub>2</sub> in the glass. This was discussed on the bases of structural role of CeO<sub>2</sub> which acts as a glass former in the region >10 mol%, while, at lower concentration, it consumed as a glass modifier.
文摘The structure of borosilicate glasses of composition 30Na<sub>2</sub>O-2Al<sub>2</sub>O<sub>3</sub>-25SiO<sub>2</sub>-xFe<sub>2</sub>O<sub>3</sub><sub></sub> (43-x) B<sub>2</sub>O<sub>3</sub> has been investigated in the composition range of 0.5 20 mol% Fe<sub>2</sub>O<sub>3</sub>. <sup>27</sup>Al, <sup>11</sup>B, <sup>29 </sup>Si MAS NMR and FTIR spectroscopies have been used to measure the fraction of different structural species in the glasses. It is evidenced from NMR data that both sodium and Fe<sub>2</sub>O<sub>3</sub> (in low region up to 7 mol%) are the main glass modifier. Structural determination for borosilicate glasses with a high content of (Fe<sub>2</sub>O<sub>3</sub>) was carried out by FTIR spectroscopy, where both <sup>11</sup>B and <sup>29</sup>Si MAS NMR are impossible because of the high quantities of paramagnetic iron (III) species present. NMR analysis was performed on borosilicate glasses containing up to 7 mol% Fe<sub>2</sub>O<sub>3</sub> and the N<sub>4</sub> values obtained by FTIR spectroscopy agree within error with the <sup>11</sup>B NMR results of the same glass samples. Fe<sub>2</sub>O<sub>3</sub> is a main glass modifier in the low-Fe<sub>2</sub>O<sub>3</sub>-content region (≤6 mol%). On other hand, it plays the role of glass former at higher content of Fe<sub>2</sub>O<sub>3</sub>. Increasing both N<sub>4 </sub>of boron tetrahedral units and chemical shift of silicon nuclei to reach maxima at 5 mol% Fe<sub>2</sub>O<sub>3</sub> confirms the role of Fe<sub>2</sub>O<sub>3</sub> as a glass modifier in the low composition region. On the other hand, fast decrease in N<sub>4</sub> with further increasing Fe<sub>2</sub>O<sub>3</sub> contents ≥6 mol%) is an evidence for iron oxide to inter the glass network as a network former.
文摘Borosilicate glasses and glass ceramics in the system 30Na2O-2Al2O3-25SiO2-xFe2O3(43-x)B2O3 (x = 0 - 20 mol%) have been prepared and studied by distinguished techniques. X-ray diffraction (XRD), transmission electron microscope (TEM), electron diffraction pattern (EDP) and SEM experiments are applied to explore the induced structural changes. Nanometer-sized species of polycrystalline structure are formed particularly in low Fe2O3 containing glasses. The size of the crystallites is found to depend on Fe2O3 concentrations. It is ranged from 10 to 33 nanometers. Structurally, these materials are suggested to contain different components, crystalline component and an interfacial component which situated between the crystallized domains. Presence of these components affects the atomic arrangement without short- or long-range order. An intermediate range ordered structure is dominant in glass ceramics of Fe2O3 2O3 concentration, since more disordered structure of lower size is present. These structural changes are found to be connected with the role of Fe2O3 and Na2O in glasses. Na2O is the strong glass modifier in the studied composition region, while Fe2O3 is consumed also as a modifier in composition of 2O3 is mainly dominant in the composition region of higher iron oxide concentration (8 - 20 mol%).
文摘Silver phosphate glasses of general formula xAg2O·(100 - x)P2O5 have been investigated over compositional range from x = 40 to 62.5 mol%. The local structure around phosphorus atom has been studied via 31P nuclear magnetic resonance. The distribution of [PO4]Qn species as a function of composition has been shown to slightly deviate from the simple binary alkali phosphate model. An anomalous behavior has been recorded and interpreted in terms of mixed ring-chain effect in metaphosphate composition. The splitting of NMR spectra into sub resonances is assigned to different binding sites characterizing Q1 ring and Q1 chain structure. Higher Ag2O concentration (≥50 mol%) leads to formation of phosphate groups with specific resonance peaks which are mainly related to pyro and orthophosphate species. The rate of change of the chemical shift of the 31P NMR depends on the bond type, which in turn reflects the extent of double bonding between phosphorus and oxygen atoms. Increasing concentration of Q0 with increasing Ag2O content leads to decreasing quantities of bridging and double bonds. As a consequence, specific symmetric resonance peak of higher intensity and chemical shift (Q0) is a feature of silver rich glasses (orthophosphate). The latter species is therefore proposed to compose of separated membered rings,?which cause deshielding of phosphate units.?XRD and EDP studies have shown that, amorphous phosphate network is the dominant structure of glasses containing ≤ 55 mol% Ag2O. Some ordered and well crystallized phases are formed at higher Ag2O concentration. Increasing non-bridging oxygen atoms is shown to have the main effect on crystallization behavior. Orthophosphate composition is the most crystalline one among the other compositions (ultra, meta- and pyrophosphate). Presence of orthophosphate species which typically contains highest concentration from isolated Q0 units is the main reason for building up crystalline Ag3PO4phosphate phase.
文摘Glasses in the system 24.5Na<sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O·24.5CaO·6P</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O</span><sub><span style="font-size:12px;font-family:Verdana;">5</span></sub><span style="font-family:Verdana;">·xSrO·(45-x)SiO</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> have been</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> studied in the composition region of x = 0 - 15 mol%. The as prepared glasses are transparent and have an amorphous network structure. On the otherhand, heat treated glasses are transformed to opaque white glass ceramic characterized by their highly crystalline network structure. Crystalline apatite (calcium phosphate, Ca</span><sub><span style="font-size:12px;font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">(PO</span><sub><span style="font-size:12px;font-family:Verdana;">4</span></sub><span style="font-family:Verdana;">)</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">, wollastonite (calcium silicate, CaSiO</span><sub><span style="font-size:12px;font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">), and strontium calcium phosphate</span></span><span style="font-family:Verdana;"> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">Ca</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">Sr(PO</span><sub><span style="font-size:12px;font-family:Verdana;">4</span></sub><span style="font-family:Verdana;">)</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> </span></span><span style="font-family:;" "=""><span style="font-family:Verdana;">are the main well-formed crystalline species played the major role in material bioactivity. Increasing SrO leads to enhancing material crystallite and enhances the hardness of the host glass matrix. The change of XRD spectra, </span><sup><span style="font-size:12px;font-family:Verdana;">31</span></sup><span style="font-family:Verdana;">P NMR chemical shift and hardness number upon increasing SrO are considered due to modification of the apatit Ca(PO</span><sub><span style="font-size:12px;font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">)</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> to involve Sr ions inducing Ca</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">Sr (PO</span><sub><span style="font-size:12px;font-family:Verdana;">4</span></sub><span style="font-family:Verdana;">)</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> apatite one. Such species play the role in enhancing material properties and hardness.</span></span>
文摘Cerium Pyrophosphate glass is prepared and investigated by different structural techniques. Resin modified glass ionomer cements (RGICs) of pyro cerium phosphate (40CeO2-60P2Os) composition doped with different concentrations from GaCl Phthalocyanine (C32H16ClGaN8) have been also prepared and studied for the first time. Different techniques have been applied to shed?light on the structural changes induced upon addition of GaCl-Phthalocyanine. The corresponding changes in material structure are widely approved by results of 31P magic angle spinning nuclear magnetic resonance (MAS-NMR), X-Ray diffraction and FTIR spectroscopy. The network structure of both base glass and GIC free from C32H16ClGaN8 is confirmed to be amorphous. Doping even with little concentration from GaCl-Phthalocyanine leads to changing the network structure from amorphous to a highly crystalline one. Formulation of GaCl-Phthalocyanine with water soluble acid leads to monocrystalline structure due to monoclinic lattice structure of Phthalocyanine. Carbonated hydroxyl cerium and gallium phosphate structural phases are evidenced to be formed upon GaCl-Phthalocyanine addition. Presence of such bioactive phases can support that the prepared GICs of considerable C32H16ClGaN8 concentration (1 and 1.5 mol%) can be applied as biocompatible materials used in biodental applications. The morphologies of some selected samples were characterized by SEM. The micrographs have revealed that formulating of cerium phosphate powder of the amorphous glass with polymeric acid successfully led to the formation of CePO4-H2O nanofibrous bundles. But formulation with GIC containing GaCl-Phthalocyanine can simply form co-aligned and elongated nanofibers (15 - 40 nm thick and up to ca. 1.2 m long). The formed nanofibers are mainly consisted of hydrated and carbonated CePO4 and GaPO4 nanocrystals. The hardness of the cemented material increases with increasing GaCl-Phthalocyanine concentrations.
