The integrated absorption cross section Σ abs, peak emis sion cross section σ emi, Judd-Ofeld intensity parameters Ω t(t=2,4,6), and spontaneous emission probability A R of Er 3+ ions were determined fo r...The integrated absorption cross section Σ abs, peak emis sion cross section σ emi, Judd-Ofeld intensity parameters Ω t(t=2,4,6), and spontaneous emission probability A R of Er 3+ ions were determined fo r Erbium doped alkali and alkaline earth phosphate glasses. It is found the comp ositional dependence of σ emi is almost similar to that of Σ abs, wh ich is determined by the sum of Ω t (3Ω 2+10Ω 4+21Ω 6). In addition, the compositional dependence of Ω t was studied in these glass systems. As a resu lt, compared with Ω 4 and Ω 6, the Ω 2 has a stronger compositional depend ence on the ionic radius and content of modifiers. The covalency of Er-O bonds in phosphate glass is weaker than that in silicate glass, germanate glass, alumi nate glass, and tellurate glass, since Ω 6 of phosphate glass is relatively la rge. A R is affected by the covalency of the Er 3+ ion sites and correspon ds to the Ω 6 value.展开更多
Ce3+,Eu3+ and Tb3+ singly doped and Ce3+/Eu3+ and Ce3+/Tb3+ co-doped zinc phosphate glasses were prepared by sintering P2O5,ZnO,Ce2(C2O4)3·10H2O and Eu2O3/Tb4O7 mixtures at 1200 °C in the air for 2 h and the...Ce3+,Eu3+ and Tb3+ singly doped and Ce3+/Eu3+ and Ce3+/Tb3+ co-doped zinc phosphate glasses were prepared by sintering P2O5,ZnO,Ce2(C2O4)3·10H2O and Eu2O3/Tb4O7 mixtures at 1200 °C in the air for 2 h and then annealing at 450 °C for 10 h.The obtained glasses were homogeneous and transparent.The glasses without Ce3+ were colorless and those with Ce3+ showed slightly yellow.The singly doped glasses showed strong emissions and excitations from doped trivalent rare earth ions.Strong energy transfer from Ce3+ to...展开更多
Er^3 +/Yb^3 + phosphate glasses were fabricated. According to McCumber theory, the stimulated emission cross-section of Er^3+ ions at 1533 nm was calculated on the basis of absorption spectrum, and 0.84 × 10^-...Er^3 +/Yb^3 + phosphate glasses were fabricated. According to McCumber theory, the stimulated emission cross-section of Er^3+ ions at 1533 nm was calculated on the basis of absorption spectrum, and 0.84 × 10^-20 cm^2 is derived, the fluorescence lifetime of ^4I13/2 level is 8.5 ms. An Er^3+/Yb^3+ co-doped phosphate glass CW laser pumped by LD was demonstrated at room temperature. The maximum output power is 80 mW and slope efficiency is 16.5%.展开更多
The formation ability and thermal stability of phosphate laser protection glass doped with high Sm2O3 content were discussed. The characteristic temperatures ( Tg, Tc, Tm) were measured by DSC and the crystallization ...The formation ability and thermal stability of phosphate laser protection glass doped with high Sm2O3 content were discussed. The characteristic temperatures ( Tg, Tc, Tm) were measured by DSC and the crystallization parameter β was calculated. The results show that the forming regions would shrink and tend to closed ellipse with increasing of Sm2O3 content. Increasing of BaO/Al2O3 ratio changes the network structure of rare earth glass and improves the thermal stability finally. However, with the increasing of Sm2O3 content, the β increases firstly and then decreases, and finally the thermal stability also increases firstly and then decreases.展开更多
The regular melting-quenching method allowed isolating very large vitreous domains within the ternary system Li2O-P2O5-Fe2O3 at 1100. The vitrification and crystallization effects are discussed in terms of phosphorus ...The regular melting-quenching method allowed isolating very large vitreous domains within the ternary system Li2O-P2O5-Fe2O3 at 1100. The vitrification and crystallization effects are discussed in terms of phosphorus pentaoxide concentration (mol%). In the course of the present study, we analyzed chemical durability along the glass domain and many sample glasses were isolated. We noticed that our compounds demonstrated very high chemical resistance to attack, even with very highly concentrated mineral acid solutions. This behavior can be assigned to the presence of poorly crystalline phases in these glasses, which tended to increase as the Fe2O3 content increased. This property is a prerequisite for many interesting industrial applications. XRD, IR spectroscopy and SEM micrographs allowed an efficient investigation of the structural changes versus composition within ternary diagrams. The results were found to be consistent with the regular structural changes of phosphate glasses.展开更多
The glass system xBi2O3-(30 – x)CdO-10B2O3-20Fe2O3-40P2O5 (0 ≤ x ≤ 30 weight %), has been prepared by the melt quenching technique. The thermal stability of the glasses, their hardness as well as their chemical dur...The glass system xBi2O3-(30 – x)CdO-10B2O3-20Fe2O3-40P2O5 (0 ≤ x ≤ 30 weight %), has been prepared by the melt quenching technique. The thermal stability of the glasses, their hardness as well as their chemical durability have been investigated before and after subjecting to different gamma ray doses to insure the validity of this glass system for application to the problem of the permanent disposal for nuclear wastes. The results indicated that the glasses have well to excellent chemical durability, thermal stability and hardness with increasing Bi2O3 content on the expense of CdO, and that the effect of irradiation with gamma doses is very small.展开更多
Glasses in the ternary system Cr2O3-PbO-P2O5 were prepared by direct melting of the mixture with stoichiometric proportions of the reagents Cr2O3, PbO and (NH4)2HPO4 at 1080℃. The glasses obtained are transparent in ...Glasses in the ternary system Cr2O3-PbO-P2O5 were prepared by direct melting of the mixture with stoichiometric proportions of the reagents Cr2O3, PbO and (NH4)2HPO4 at 1080℃. The glasses obtained are transparent in colour and have a non-hygroscopic appearance. The study of the dissolution rate was carried out on ternary glasses xCr2O3-(45-x)PbO-55P2O5 with (1 ≤ x ≤ 4;mol%), immersed in distilled water at 90℃ for 24 days, indicating a maximum of chemical durability when the level of chromium oxide passed through 2 mol%. Both, IR spectra and X-ray diffraction have indicated the predominance of metaphosphate or cyclic metaphosphate groups with some traces of isolated orthophosphate groups when the Cr2O3 content is equal to x = 2. Analysis of the density values also, has showed a maximum density for x = 2 mol%. The covalent radius values of oxygen have indicated that the minimum value rcal (O2–) is observed for x = 2 mol% and therefore a relatively high reinforcement of the metal-oxygen-phosphorus (Cr-O-P) bonds. SEM Micrographs have exhibited two phases, a vitreous phase and a crystalline phase. The radical change in the structure from ultraphosphate Q3 groups to ring metaphosphate Q2 and orthophosphate groups Q0 seems to be the cause of the formation of crystallites. Beyond 2 mol% of Cr2O3, the structure of the glass changed relatively and the orthophosphate phases increased to the detriment of the metaphosphate phases. We observed a decrease in chemical durability. However, it was confirmed that the dissolution rate (DR) of the S2 analysed compound is comparable to the values of borosilicate glasses which are used as alternative materials for the immobilisation of nuclear waste substances.展开更多
We report the fabrication and spectroscopic characterization of Yb^3+-doped phosphate glass, also containing silver nitrate. Scanning electron microscopy(SEM) provides the evidence of the formation of silver nano-p...We report the fabrication and spectroscopic characterization of Yb^3+-doped phosphate glass, also containing silver nitrate. Scanning electron microscopy(SEM) provides the evidence of the formation of silver nano-particles(SNPs), which are formed as a consequence of melting and thermal decomposition of Ag NO3. Absorption spectra of the samples in the visible-to-near-infrared spectral range reveal the presence of bands centered at 410 nm associated with the SNP-plasmon resonance, and at 976 nm due to the Yb^3+. Under 916-nm laser-diode pumping, the effect of the SNP reflects that: i) the fluorescence in the 950-nm–1150-nm spectral range is strongly enhanced(~ 30 times), while the fluorescence decay time associated with the ^2F5/2→^2F7/2transition of Yb^3+ increases 25%, and ii) the basic lasing properties(saturation pumping intensity, the emission and absorption cross sections) are substantially improved.展开更多
The nonlinear optical properties of a phosphate vitreous system [(ZnO)x-(MgO)30-x-(P2O5)70], where x=8, 10, 15, 18, and 20 mol% synthesized through the melt-quenching technique have been investigated by using th...The nonlinear optical properties of a phosphate vitreous system [(ZnO)x-(MgO)30-x-(P2O5)70], where x=8, 10, 15, 18, and 20 mol% synthesized through the melt-quenching technique have been investigated by using the Z-scan technique. In the experiment, a continuous-wave laser with a wavelength of 405 nm was utilized to determine the sign and value of the nonlinear refractive (NLR) index and the absorption coefficient with closed and opened apertures of the Z-scan setup. The NLR index was found to increase with the ZnO concentration in the glass samples by an order of 10-10 cm2·W-1. The real and imaginary parts of the third-order nonlinear susceptibility were calculated by referring to the NLR index (n2) and absorption coefficient (β) of the samples. The value of the third-order nonlinear susceptibility was presented by nonlinear refractive or absorptive behavior of phosphate glasses for proper utilization in nonlinear optical devices. Based on the measurement, the positive sign of the NLR index shows a self-focusing phenomenon. The figures of merit for each sample were calculated to judge the potential of phosphate glasses for application in optical switching.展开更多
Mn^2+ doped ZnO-P2O5 glasses emit red fluorescence, which shows that Mn^2+ ion doped in zinc phosphate glass is octahedrally coordinated. Moreover, glass samples exhibit bright red long lasting phosphorescence (LLP...Mn^2+ doped ZnO-P2O5 glasses emit red fluorescence, which shows that Mn^2+ ion doped in zinc phosphate glass is octahedrally coordinated. Moreover, glass samples exhibit bright red long lasting phosphorescence (LLP) when the mole percent of ZnO are more than 60%. After turnoff the irradiation source of UV lamp peaking at 254 nm, the red phosphorescence can be observed for about 6 h in the limit of light perception for naked eyes (0.32 mcd/m^2). Photoluminescence (PL) spectra, LLP emission spectra and decay curves were detected. Increasing MnO or ZnO content, the phosphorescence intensity can be improved distinctly and the emission wavelength can be also adjusted from 595 nm to 628 nm. According to the structural characteristic of zinc phosphates glasses, we suggest that non-bridge oxygen (NBO) is probably related with the arising of LLE Meantime, the variation of crystal field intensity induced that the LLP emission wavelength red shifts.展开更多
Glasses of the compositions 20Li2O-(50 - x)Li2WO4-xFe2O3-30P2O5 where (x = 0, 1, 5, 8, 10, 15 mol%) were elaborated by the melt-quenching route. Synthesized glasses are characterized using X-ray diffraction (XRD), Fou...Glasses of the compositions 20Li2O-(50 - x)Li2WO4-xFe2O3-30P2O5 where (x = 0, 1, 5, 8, 10, 15 mol%) were elaborated by the melt-quenching route. Synthesized glasses are characterized using X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), differential scanning calorimetric?(DSC), and density determination. The XRD patterns confirmed the?amorphous nature of samples, and IR spectra showed the structural groups and highlight the depolymerization of phosphate network with the introduction of iron oxide. It is found that the structural unit Q2 converts to Q1 and Q0 as Fe2O3 replaces Li2WO4. Chemical durability tests on the glasses have shown that the compositions containing pyrophosphate (Q1) and orthophosphate (Q0) units are more water-resist. The electrical conductivity measurements were performed by complex impedance spectroscopy in the frequency range of 20 - 106 Hz at various temperatures from ambient to 400°C. It is found that the conductivity is activated thermally and follows an Arrhenius law. The obtained electrical data were analyzed by the modulus formalism and dielectric formalism. The determined asymmetric nature of? spectra suggested that the relaxation behavior is non-Debye and characterized by the stretched exponent parameter展开更多
Lithium cadmium phosphate glasses were prepared by melt quench technique. These glasses contain a mole % composition of x% Li2O-(50-x)% CdO-50%P2O5. The quantity x varies from 0-40 mole%. The physical properties repor...Lithium cadmium phosphate glasses were prepared by melt quench technique. These glasses contain a mole % composition of x% Li2O-(50-x)% CdO-50%P2O5. The quantity x varies from 0-40 mole%. The physical properties reported in this paper are mass density ρ, modulus of rigidity η, coefficient of linear expansion α, transition temperature Tg, Softening temperature Ts, Oxygen packing density, Molar volume and lithium ion concentration. The mass density, oxygen packing density, modulus rigidity, transition temperature and softening temperature show decreasing trend with increasing concentration of lithium ions in these glasses, where molar volume and coefficient of linear expansion increases with increasing concentration of Li2O.展开更多
Effects of Zn/P ratio on the structures and properties of glasses with the general composition of (80-x)ZnO-20Fe2O3 -xP2O5 (x=40, 45, 50, 55,60) (molar fraction, %) were investigated. Glass structure was measured by i...Effects of Zn/P ratio on the structures and properties of glasses with the general composition of (80-x)ZnO-20Fe2O3 -xP2O5 (x=40, 45, 50, 55,60) (molar fraction, %) were investigated. Glass structure was measured by infrared absorption spectrum. Glass density (ρ) was measured by the Archimedes method. Coefficients of thermal expansion (α) and characterization temperature were obtained by a dilatometer. Water durability of each glass was estimated from the dissolution rate(DR )in water at 90 C for 24 h. With increasing Zn/P ratio, water durability of zinc-iron phosphate glasses increases dramatically without large increase in the characterization temperature. (80-x)ZnO-20Fe2O3 -xP2O5 glasses with 0.3≤Zn/P≤0.5 are suit for low-to-mid temperature sealing application for substrates with α<8.0×10-6C-1 .展开更多
Currently, phosphate based glasses have been potential future biomaterial for medical application due to excellent cytocompatibility and fully bioresorbability. In this study, phosphate based glass system with composi...Currently, phosphate based glasses have been potential future biomaterial for medical application due to excellent cytocompatibility and fully bioresorbability. In this study, phosphate based glass system with composition of 48P2O5-12B2O3-(25-X)MgO-14CaO-1Na2O-(X)Fe2O3 (X = 6, 8, 10) and 45P2O5-(Y)B2O3-(32-Y)MgO-14CaO-1Na2O-8Fe2O3 (Y = 12, 15, 20), was prepared via a melting quenching process. The effect of replacing MgO with Fe2O3 and B2O3 on the structural, thermal, degradation properties of phosphate based glass was investigated. Fourier Transform Infrared (FTIR) spectroscopy and Raman spectroscopy analysis confirmed the polymerisation of phosphate based glass network with addition of Fe2O3, thus the processing window was observed to increase whilst the dissolution rate was reduced, attributed to the formation of Fe-O-P cross-link. As the effect on the glass structure stability was demonstrated by both B2O3 and MgO, the nonlinear variation of thermal stability and degradation behaviour was observed for glass system with substitution of MgO by B2O3. However, due to the lower dissolution rate of glass system when compared to the biocompatible phosphate based glass in preliminary study, the expected cytocompatibility could be confirmed in the downstream activities.展开更多
We investigate high-modulus degradable materials intended to replace metals in biomedical applications.These are typically composites comprising a polylactide(PLA)matrix reinforced with phosphate glass fibres,which pr...We investigate high-modulus degradable materials intended to replace metals in biomedical applications.These are typically composites comprising a polylactide(PLA)matrix reinforced with phosphate glass fibres,which provide reinforcement similar to E-glass but are entirely degradable in water to produce,principally,calcium phosphate.We have made composites using a variety of fibre architectures,from non-woven random mats to unidirectional fibre tapes.Flexural properties in the region of 30 GPa modulus and 350 MPa strength have been achieved-directly comparable to quoted values for human cortical bone.In collaboration with other groups we have begun to consider the development of foamed systems with structures mimicking cancellous bone and this has shown significant promise.The fibres in these foamed structures provide improved creep resistance and reinforcement of the pore walls.To date the materials have exhibited excellent cellular responses in vitro and further studies are due to include consideration of the surface character of the materials and the influence of this on cell interaction, both with the composites and the glass fibres themselves,which show promise as a standalone porous scaffold.展开更多
Abstract: The crystallization kinetics of Li20-A12O3-GeO2-P205 (LAGP) glass fabricated via the conventional melt-quenching method was studied by differential scanning calorimetry (DSC) under non- isothermal condi...Abstract: The crystallization kinetics of Li20-A12O3-GeO2-P205 (LAGP) glass fabricated via the conventional melt-quenching method was studied by differential scanning calorimetry (DSC) under non- isothermal condition at different heating rates. The activation energy of glass transition Eg is 634.4 kJ/mol, indicating that LAGP glass is easy to crystallize at an elevated temperature. The activation energy of crystallization Eo and Avrami index n obtained from Matusita's model are 442.01 kJ/mol and 1.7, respectively. The value of n reveals that bulk crystallization predominates slightly over surface crystallization during crystallization process. LAGP glass-ceramics after different heat treatments have the same crystalline phases determined as major phase LiGe2(PO4)3, with A1PO4 and GeO2 as their impurity phases.展开更多
An asymmetric heating method for fusion splicing of 1 060-XP silica fiber (1 060F) and phosphate glass fiber (PGF) using an electric arc splicer has been proposed. Double joints with the lowest splice loss of 0.6 ...An asymmetric heating method for fusion splicing of 1 060-XP silica fiber (1 060F) and phosphate glass fiber (PGF) using an electric arc splicer has been proposed. Double joints with the lowest splice loss of 0.6 dB and good bending-resist strength between 1 060 F and PGF has been obtained. The main reasons affecting fiber splice loss and strength have been analyzed.展开更多
Chromium iron phosphate glass was investigated for use as waste form because of its improved chemical durability. The introduction of chromium in sodium-iron-phosphate glass is used to compare its effect with iron in ...Chromium iron phosphate glass was investigated for use as waste form because of its improved chemical durability. The introduction of chromium in sodium-iron-phosphate glass is used to compare its effect with iron in inhibition of corrosion. The sodium-chromium-iron phosphate glass of composition 10Na2O-30Fe2O3-5Cr2O3-55P2O5 (mol%) was produced by melting batches of (99, 98% pure) Cr2O3, Fe2O3, Na2CO3, and (NH4)2HPO4 at 1080°C for one hour and pouring the liquid into steel mold. The sample was annealed at 680°C for 48 h. We have performed the measurement of X-Ray Diffraction (XRD), Scanning Electronic Microscopy (SEM), Infra-Red spectroscopy (IR), and the chemical durability. The IR of the glass studied, contains two dominant bands, which were characteristic of pyrophosphate groups, (P-O) stretching mode of P-O non bridging oxygen at 1055 cm-1 and sym stretching mode of bridging oxygen at444 cm-1 respectively. There is also a band at603 cm-1 attributed to isolated tetrahedral units (PO4)3-. The chemical durability of the glass was investigated by measuring the weight loss in distilled water at 90°C for 22 days.展开更多
Radioactive fluoride wastes are generated during the operation of molten salt reactors(MSRs) and reprocessing of their spent fuel.Immobilization of these wastes in borosilicate glass is not feasible because of the ver...Radioactive fluoride wastes are generated during the operation of molten salt reactors(MSRs) and reprocessing of their spent fuel.Immobilization of these wastes in borosilicate glass is not feasible because of the very low solubility of fluorides in this host.Alternative candidates are thus an active topic of research including phosphatebased glasses,crystalline ceramics,and hybrid glass-ceramic systems.In this study,mixed fluorides were employed as simulated MSRs waste and incorporated into sodium aluminophosphate glass to obtain phosphate-based waste form.These waste forms were characterized by X-ray diffraction,Raman spectroscopy,and scanning electron microscopy.Leaching tests were performed in deionized water using the product consistency test A method.This study demonstrates that up to 20 mol%of simulated radioactive waste can be introduced into the NaA1 P glass matrix,and the chemical durability is much better than that of borosilicate.The addition of Fe_2O_3 in the NaAlP glass matrix results in increases of the chemical durability at the expense of fluoride loading(to 6.4 mol%).Phosphate glass vitrification of radioactive waste containing fluorides is a potential method to treat and dispose of MSR wastes.展开更多
Solid-state impedance spectroscopy(SS-IS)was used to investigate the influence of structural modifications resulting from the addition of Nb2O5 on the dielectric properties and relaxation processes in the quaternary m...Solid-state impedance spectroscopy(SS-IS)was used to investigate the influence of structural modifications resulting from the addition of Nb2O5 on the dielectric properties and relaxation processes in the quaternary mixed glass former(MGF)system 35Na_(2)O–10V_(2)O_(5)–(55-x)P_(2)O_(5)–xNb_(2)O_(5)(x=0–40,mol%).The dielectric parameters,including the dielectric strength and dielectric loss,are determined from the frequency and temperature-dependent complex permittivity data,revealing a significant dependence on the Nb2O5 content.The transition from a predominantly phosphate glass network(x<10,region I)to a mixed niobate–phosphate glass net-work(10≤x≤20,region II)leads to an increase in the dielectric parameters,which correlates with the observed trend in the direct-cur-rent(DC)conductivity.In the predominantly niobate network(x≥25,region III),the highly polarizable nature of Nb5+ions leads to a fur-ther increase in the dielectric permittivity and dielectric strength.This is particularly evident in Nb-40 glass-ceramic,which contains Na_(13)Nb_(35)O_(94) crystalline phase with a tungsten bronze structure and exhibits the highest dielectric permittivity of 61.81 and the lowest loss factor of 0.032 at 303 K and 10 kHz.The relaxation studies,analyzed through modulus formalism and complex impedance data,show that DC conductivity and relaxation processes are governed by the same mechanism,attributed to ionic conductivity.In contrast to glasses with a single peak in frequency dependence of imaginary part of electrical modulus,M″(ω),Nb-40 glass-ceramic exhibits two distinct contributions with similar relaxation times.The high-frequency peak indicates bulk ionic conductivity,while the additional low-fre-quency peak is associated with the grain boundary effect,confirmed by the electrical equivalent circuit(EEC)modelling.The scaling characteristics of permittivity and conductivity spectra,along with the electrical modulus,validate time-temperature superposition and demonstrate a strong correlation with composition and modification of the glass structure upon Nb_(2)O_(5) incorporation.展开更多
基金Funded by the Natural Science Foundation of Guangdong Prov ince(013013) and the Science and Technology Plan of Guangdong Province(2002B11604)
文摘The integrated absorption cross section Σ abs, peak emis sion cross section σ emi, Judd-Ofeld intensity parameters Ω t(t=2,4,6), and spontaneous emission probability A R of Er 3+ ions were determined fo r Erbium doped alkali and alkaline earth phosphate glasses. It is found the comp ositional dependence of σ emi is almost similar to that of Σ abs, wh ich is determined by the sum of Ω t (3Ω 2+10Ω 4+21Ω 6). In addition, the compositional dependence of Ω t was studied in these glass systems. As a resu lt, compared with Ω 4 and Ω 6, the Ω 2 has a stronger compositional depend ence on the ionic radius and content of modifiers. The covalency of Er-O bonds in phosphate glass is weaker than that in silicate glass, germanate glass, alumi nate glass, and tellurate glass, since Ω 6 of phosphate glass is relatively la rge. A R is affected by the covalency of the Er 3+ ion sites and correspon ds to the Ω 6 value.
基金supported by the National Natural Science Foundation of China (10704090, 10874253)Foundation of the Education Committee of Chongqing (10874173)
文摘Ce3+,Eu3+ and Tb3+ singly doped and Ce3+/Eu3+ and Ce3+/Tb3+ co-doped zinc phosphate glasses were prepared by sintering P2O5,ZnO,Ce2(C2O4)3·10H2O and Eu2O3/Tb4O7 mixtures at 1200 °C in the air for 2 h and then annealing at 450 °C for 10 h.The obtained glasses were homogeneous and transparent.The glasses without Ce3+ were colorless and those with Ce3+ showed slightly yellow.The singly doped glasses showed strong emissions and excitations from doped trivalent rare earth ions.Strong energy transfer from Ce3+ to...
文摘Er^3 +/Yb^3 + phosphate glasses were fabricated. According to McCumber theory, the stimulated emission cross-section of Er^3+ ions at 1533 nm was calculated on the basis of absorption spectrum, and 0.84 × 10^-20 cm^2 is derived, the fluorescence lifetime of ^4I13/2 level is 8.5 ms. An Er^3+/Yb^3+ co-doped phosphate glass CW laser pumped by LD was demonstrated at room temperature. The maximum output power is 80 mW and slope efficiency is 16.5%.
基金Project supported by the Senior Intellectuals Fund of Jiangsu University (05JDGO46)"333 Project" Fund of Jiangsu Province (JS2001-78)
文摘The formation ability and thermal stability of phosphate laser protection glass doped with high Sm2O3 content were discussed. The characteristic temperatures ( Tg, Tc, Tm) were measured by DSC and the crystallization parameter β was calculated. The results show that the forming regions would shrink and tend to closed ellipse with increasing of Sm2O3 content. Increasing of BaO/Al2O3 ratio changes the network structure of rare earth glass and improves the thermal stability finally. However, with the increasing of Sm2O3 content, the β increases firstly and then decreases, and finally the thermal stability also increases firstly and then decreases.
文摘The regular melting-quenching method allowed isolating very large vitreous domains within the ternary system Li2O-P2O5-Fe2O3 at 1100. The vitrification and crystallization effects are discussed in terms of phosphorus pentaoxide concentration (mol%). In the course of the present study, we analyzed chemical durability along the glass domain and many sample glasses were isolated. We noticed that our compounds demonstrated very high chemical resistance to attack, even with very highly concentrated mineral acid solutions. This behavior can be assigned to the presence of poorly crystalline phases in these glasses, which tended to increase as the Fe2O3 content increased. This property is a prerequisite for many interesting industrial applications. XRD, IR spectroscopy and SEM micrographs allowed an efficient investigation of the structural changes versus composition within ternary diagrams. The results were found to be consistent with the regular structural changes of phosphate glasses.
文摘The glass system xBi2O3-(30 – x)CdO-10B2O3-20Fe2O3-40P2O5 (0 ≤ x ≤ 30 weight %), has been prepared by the melt quenching technique. The thermal stability of the glasses, their hardness as well as their chemical durability have been investigated before and after subjecting to different gamma ray doses to insure the validity of this glass system for application to the problem of the permanent disposal for nuclear wastes. The results indicated that the glasses have well to excellent chemical durability, thermal stability and hardness with increasing Bi2O3 content on the expense of CdO, and that the effect of irradiation with gamma doses is very small.
文摘Glasses in the ternary system Cr2O3-PbO-P2O5 were prepared by direct melting of the mixture with stoichiometric proportions of the reagents Cr2O3, PbO and (NH4)2HPO4 at 1080℃. The glasses obtained are transparent in colour and have a non-hygroscopic appearance. The study of the dissolution rate was carried out on ternary glasses xCr2O3-(45-x)PbO-55P2O5 with (1 ≤ x ≤ 4;mol%), immersed in distilled water at 90℃ for 24 days, indicating a maximum of chemical durability when the level of chromium oxide passed through 2 mol%. Both, IR spectra and X-ray diffraction have indicated the predominance of metaphosphate or cyclic metaphosphate groups with some traces of isolated orthophosphate groups when the Cr2O3 content is equal to x = 2. Analysis of the density values also, has showed a maximum density for x = 2 mol%. The covalent radius values of oxygen have indicated that the minimum value rcal (O2–) is observed for x = 2 mol% and therefore a relatively high reinforcement of the metal-oxygen-phosphorus (Cr-O-P) bonds. SEM Micrographs have exhibited two phases, a vitreous phase and a crystalline phase. The radical change in the structure from ultraphosphate Q3 groups to ring metaphosphate Q2 and orthophosphate groups Q0 seems to be the cause of the formation of crystallites. Beyond 2 mol% of Cr2O3, the structure of the glass changed relatively and the orthophosphate phases increased to the detriment of the metaphosphate phases. We observed a decrease in chemical durability. However, it was confirmed that the dissolution rate (DR) of the S2 analysed compound is comparable to the values of borosilicate glasses which are used as alternative materials for the immobilisation of nuclear waste substances.
基金financially supported by the CONACy T(Grant No.CB-2009-136186-F)
文摘We report the fabrication and spectroscopic characterization of Yb^3+-doped phosphate glass, also containing silver nitrate. Scanning electron microscopy(SEM) provides the evidence of the formation of silver nano-particles(SNPs), which are formed as a consequence of melting and thermal decomposition of Ag NO3. Absorption spectra of the samples in the visible-to-near-infrared spectral range reveal the presence of bands centered at 410 nm associated with the SNP-plasmon resonance, and at 976 nm due to the Yb^3+. Under 916-nm laser-diode pumping, the effect of the SNP reflects that: i) the fluorescence in the 950-nm–1150-nm spectral range is strongly enhanced(~ 30 times), while the fluorescence decay time associated with the ^2F5/2→^2F7/2transition of Yb^3+ increases 25%, and ii) the basic lasing properties(saturation pumping intensity, the emission and absorption cross sections) are substantially improved.
基金Project supported by the Ministry of Higher Education(Grant Nos.1-11-08-664FR/F1 and 01-0410-861FR)
文摘The nonlinear optical properties of a phosphate vitreous system [(ZnO)x-(MgO)30-x-(P2O5)70], where x=8, 10, 15, 18, and 20 mol% synthesized through the melt-quenching technique have been investigated by using the Z-scan technique. In the experiment, a continuous-wave laser with a wavelength of 405 nm was utilized to determine the sign and value of the nonlinear refractive (NLR) index and the absorption coefficient with closed and opened apertures of the Z-scan setup. The NLR index was found to increase with the ZnO concentration in the glass samples by an order of 10-10 cm2·W-1. The real and imaginary parts of the third-order nonlinear susceptibility were calculated by referring to the NLR index (n2) and absorption coefficient (β) of the samples. The value of the third-order nonlinear susceptibility was presented by nonlinear refractive or absorptive behavior of phosphate glasses for proper utilization in nonlinear optical devices. Based on the measurement, the positive sign of the NLR index shows a self-focusing phenomenon. The figures of merit for each sample were calculated to judge the potential of phosphate glasses for application in optical switching.
基金Funded by the State Key Project of Basic Research of China(No.GB1998061312)
文摘Mn^2+ doped ZnO-P2O5 glasses emit red fluorescence, which shows that Mn^2+ ion doped in zinc phosphate glass is octahedrally coordinated. Moreover, glass samples exhibit bright red long lasting phosphorescence (LLP) when the mole percent of ZnO are more than 60%. After turnoff the irradiation source of UV lamp peaking at 254 nm, the red phosphorescence can be observed for about 6 h in the limit of light perception for naked eyes (0.32 mcd/m^2). Photoluminescence (PL) spectra, LLP emission spectra and decay curves were detected. Increasing MnO or ZnO content, the phosphorescence intensity can be improved distinctly and the emission wavelength can be also adjusted from 595 nm to 628 nm. According to the structural characteristic of zinc phosphates glasses, we suggest that non-bridge oxygen (NBO) is probably related with the arising of LLE Meantime, the variation of crystal field intensity induced that the LLP emission wavelength red shifts.
文摘Glasses of the compositions 20Li2O-(50 - x)Li2WO4-xFe2O3-30P2O5 where (x = 0, 1, 5, 8, 10, 15 mol%) were elaborated by the melt-quenching route. Synthesized glasses are characterized using X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), differential scanning calorimetric?(DSC), and density determination. The XRD patterns confirmed the?amorphous nature of samples, and IR spectra showed the structural groups and highlight the depolymerization of phosphate network with the introduction of iron oxide. It is found that the structural unit Q2 converts to Q1 and Q0 as Fe2O3 replaces Li2WO4. Chemical durability tests on the glasses have shown that the compositions containing pyrophosphate (Q1) and orthophosphate (Q0) units are more water-resist. The electrical conductivity measurements were performed by complex impedance spectroscopy in the frequency range of 20 - 106 Hz at various temperatures from ambient to 400°C. It is found that the conductivity is activated thermally and follows an Arrhenius law. The obtained electrical data were analyzed by the modulus formalism and dielectric formalism. The determined asymmetric nature of? spectra suggested that the relaxation behavior is non-Debye and characterized by the stretched exponent parameter
文摘Lithium cadmium phosphate glasses were prepared by melt quench technique. These glasses contain a mole % composition of x% Li2O-(50-x)% CdO-50%P2O5. The quantity x varies from 0-40 mole%. The physical properties reported in this paper are mass density ρ, modulus of rigidity η, coefficient of linear expansion α, transition temperature Tg, Softening temperature Ts, Oxygen packing density, Molar volume and lithium ion concentration. The mass density, oxygen packing density, modulus rigidity, transition temperature and softening temperature show decreasing trend with increasing concentration of lithium ions in these glasses, where molar volume and coefficient of linear expansion increases with increasing concentration of Li2O.
基金Project(7602110340) supported by the Postdoctoral Science Foundation of Central South University, ChinaProject(721500277)supported by the Fundamental Research Funds for the Central Universities of China
文摘Effects of Zn/P ratio on the structures and properties of glasses with the general composition of (80-x)ZnO-20Fe2O3 -xP2O5 (x=40, 45, 50, 55,60) (molar fraction, %) were investigated. Glass structure was measured by infrared absorption spectrum. Glass density (ρ) was measured by the Archimedes method. Coefficients of thermal expansion (α) and characterization temperature were obtained by a dilatometer. Water durability of each glass was estimated from the dissolution rate(DR )in water at 90 C for 24 h. With increasing Zn/P ratio, water durability of zinc-iron phosphate glasses increases dramatically without large increase in the characterization temperature. (80-x)ZnO-20Fe2O3 -xP2O5 glasses with 0.3≤Zn/P≤0.5 are suit for low-to-mid temperature sealing application for substrates with α<8.0×10-6C-1 .
文摘Currently, phosphate based glasses have been potential future biomaterial for medical application due to excellent cytocompatibility and fully bioresorbability. In this study, phosphate based glass system with composition of 48P2O5-12B2O3-(25-X)MgO-14CaO-1Na2O-(X)Fe2O3 (X = 6, 8, 10) and 45P2O5-(Y)B2O3-(32-Y)MgO-14CaO-1Na2O-8Fe2O3 (Y = 12, 15, 20), was prepared via a melting quenching process. The effect of replacing MgO with Fe2O3 and B2O3 on the structural, thermal, degradation properties of phosphate based glass was investigated. Fourier Transform Infrared (FTIR) spectroscopy and Raman spectroscopy analysis confirmed the polymerisation of phosphate based glass network with addition of Fe2O3, thus the processing window was observed to increase whilst the dissolution rate was reduced, attributed to the formation of Fe-O-P cross-link. As the effect on the glass structure stability was demonstrated by both B2O3 and MgO, the nonlinear variation of thermal stability and degradation behaviour was observed for glass system with substitution of MgO by B2O3. However, due to the lower dissolution rate of glass system when compared to the biocompatible phosphate based glass in preliminary study, the expected cytocompatibility could be confirmed in the downstream activities.
文摘We investigate high-modulus degradable materials intended to replace metals in biomedical applications.These are typically composites comprising a polylactide(PLA)matrix reinforced with phosphate glass fibres,which provide reinforcement similar to E-glass but are entirely degradable in water to produce,principally,calcium phosphate.We have made composites using a variety of fibre architectures,from non-woven random mats to unidirectional fibre tapes.Flexural properties in the region of 30 GPa modulus and 350 MPa strength have been achieved-directly comparable to quoted values for human cortical bone.In collaboration with other groups we have begun to consider the development of foamed systems with structures mimicking cancellous bone and this has shown significant promise.The fibres in these foamed structures provide improved creep resistance and reinforcement of the pore walls.To date the materials have exhibited excellent cellular responses in vitro and further studies are due to include consideration of the surface character of the materials and the influence of this on cell interaction, both with the composites and the glass fibres themselves,which show promise as a standalone porous scaffold.
基金National Natural Science Foundation of China (NSFC) (No. 60808024)
文摘Abstract: The crystallization kinetics of Li20-A12O3-GeO2-P205 (LAGP) glass fabricated via the conventional melt-quenching method was studied by differential scanning calorimetry (DSC) under non- isothermal condition at different heating rates. The activation energy of glass transition Eg is 634.4 kJ/mol, indicating that LAGP glass is easy to crystallize at an elevated temperature. The activation energy of crystallization Eo and Avrami index n obtained from Matusita's model are 442.01 kJ/mol and 1.7, respectively. The value of n reveals that bulk crystallization predominates slightly over surface crystallization during crystallization process. LAGP glass-ceramics after different heat treatments have the same crystalline phases determined as major phase LiGe2(PO4)3, with A1PO4 and GeO2 as their impurity phases.
基金Funded by the Guangdong Science and Technology Program (No.2005A10602001)the Guangzhou Science and Technology Program (No.2006Z2-D0161)the Program for New Century Excellent Talents (No.NCET-04-0821)
文摘An asymmetric heating method for fusion splicing of 1 060-XP silica fiber (1 060F) and phosphate glass fiber (PGF) using an electric arc splicer has been proposed. Double joints with the lowest splice loss of 0.6 dB and good bending-resist strength between 1 060 F and PGF has been obtained. The main reasons affecting fiber splice loss and strength have been analyzed.
文摘Chromium iron phosphate glass was investigated for use as waste form because of its improved chemical durability. The introduction of chromium in sodium-iron-phosphate glass is used to compare its effect with iron in inhibition of corrosion. The sodium-chromium-iron phosphate glass of composition 10Na2O-30Fe2O3-5Cr2O3-55P2O5 (mol%) was produced by melting batches of (99, 98% pure) Cr2O3, Fe2O3, Na2CO3, and (NH4)2HPO4 at 1080°C for one hour and pouring the liquid into steel mold. The sample was annealed at 680°C for 48 h. We have performed the measurement of X-Ray Diffraction (XRD), Scanning Electronic Microscopy (SEM), Infra-Red spectroscopy (IR), and the chemical durability. The IR of the glass studied, contains two dominant bands, which were characteristic of pyrophosphate groups, (P-O) stretching mode of P-O non bridging oxygen at 1055 cm-1 and sym stretching mode of bridging oxygen at444 cm-1 respectively. There is also a band at603 cm-1 attributed to isolated tetrahedral units (PO4)3-. The chemical durability of the glass was investigated by measuring the weight loss in distilled water at 90°C for 22 days.
文摘Radioactive fluoride wastes are generated during the operation of molten salt reactors(MSRs) and reprocessing of their spent fuel.Immobilization of these wastes in borosilicate glass is not feasible because of the very low solubility of fluorides in this host.Alternative candidates are thus an active topic of research including phosphatebased glasses,crystalline ceramics,and hybrid glass-ceramic systems.In this study,mixed fluorides were employed as simulated MSRs waste and incorporated into sodium aluminophosphate glass to obtain phosphate-based waste form.These waste forms were characterized by X-ray diffraction,Raman spectroscopy,and scanning electron microscopy.Leaching tests were performed in deionized water using the product consistency test A method.This study demonstrates that up to 20 mol%of simulated radioactive waste can be introduced into the NaA1 P glass matrix,and the chemical durability is much better than that of borosilicate.The addition of Fe_2O_3 in the NaAlP glass matrix results in increases of the chemical durability at the expense of fluoride loading(to 6.4 mol%).Phosphate glass vitrification of radioactive waste containing fluorides is a potential method to treat and dispose of MSR wastes.
文摘Solid-state impedance spectroscopy(SS-IS)was used to investigate the influence of structural modifications resulting from the addition of Nb2O5 on the dielectric properties and relaxation processes in the quaternary mixed glass former(MGF)system 35Na_(2)O–10V_(2)O_(5)–(55-x)P_(2)O_(5)–xNb_(2)O_(5)(x=0–40,mol%).The dielectric parameters,including the dielectric strength and dielectric loss,are determined from the frequency and temperature-dependent complex permittivity data,revealing a significant dependence on the Nb2O5 content.The transition from a predominantly phosphate glass network(x<10,region I)to a mixed niobate–phosphate glass net-work(10≤x≤20,region II)leads to an increase in the dielectric parameters,which correlates with the observed trend in the direct-cur-rent(DC)conductivity.In the predominantly niobate network(x≥25,region III),the highly polarizable nature of Nb5+ions leads to a fur-ther increase in the dielectric permittivity and dielectric strength.This is particularly evident in Nb-40 glass-ceramic,which contains Na_(13)Nb_(35)O_(94) crystalline phase with a tungsten bronze structure and exhibits the highest dielectric permittivity of 61.81 and the lowest loss factor of 0.032 at 303 K and 10 kHz.The relaxation studies,analyzed through modulus formalism and complex impedance data,show that DC conductivity and relaxation processes are governed by the same mechanism,attributed to ionic conductivity.In contrast to glasses with a single peak in frequency dependence of imaginary part of electrical modulus,M″(ω),Nb-40 glass-ceramic exhibits two distinct contributions with similar relaxation times.The high-frequency peak indicates bulk ionic conductivity,while the additional low-fre-quency peak is associated with the grain boundary effect,confirmed by the electrical equivalent circuit(EEC)modelling.The scaling characteristics of permittivity and conductivity spectra,along with the electrical modulus,validate time-temperature superposition and demonstrate a strong correlation with composition and modification of the glass structure upon Nb_(2)O_(5) incorporation.