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
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
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
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
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
Because of the influence of OH groups in phosphate glasses on the radiation of rare-earth ions, the laser performance is degraded. The laser efficiency and the small signal gain experiment of several phosphate glass s...Because of the influence of OH groups in phosphate glasses on the radiation of rare-earth ions, the laser performance is degraded. The laser efficiency and the small signal gain experiment of several phosphate glass samples have been done, the concentration of OH groups in glasses was calculated from the measured absorption coefficient at 3.47 μm. It is shown that the concentration of OH groups in phosphate glasses can seriously influence the laser output characteristics, and the OH groups have worse influence on the laser amplifier than laser oscillator.展开更多
Local structure and luminescent properties of lead phosphate glasses containing rare earth ions were studied. Optically active ions such as Eu^3+, Dy^3+, Tb^3+ and Er^3+ were chosen as dopants. The local structure...Local structure and luminescent properties of lead phosphate glasses containing rare earth ions were studied. Optically active ions such as Eu^3+, Dy^3+, Tb^3+ and Er^3+ were chosen as dopants. The local structure was verified using X-ray diffraction and Fourier transform inflared (FT-IR) spectroscopy. The visible luminescence bands recorded for the studied samples corresponded to ^5D0→^7Fj (J=0÷4) transitions of Eu^3+, ^4F9/2→^6Hj/2 (J=11÷15) transitions of Dy^3+, ^5D3→^7FJ, (J'=1÷6) and ^5Da→^7FJ (J=3÷6) transitions of Tb^3+, and ^4S1/2→^4I15/2 transitions of Er^3+.展开更多
Phosphate glass samples with various Yb2O3 and Er2O3 contents were synthesized by the conventional melt quenching technique and characterized by X-ray diffraction, IR absorption spectroscopy and Raman scattering spect...Phosphate glass samples with various Yb2O3 and Er2O3 contents were synthesized by the conventional melt quenching technique and characterized by X-ray diffraction, IR absorption spectroscopy and Raman scattering spectroscopy. The absorption, emission spectra and fluorescence decay studies were carried out both at low and room temperatures. Results showed the existence of several sites occupied by the rare earth ions in the phosphate glass. Up-conversion and cooperative fluorescence were also discussed.展开更多
The phosphate glasses doped with Eu2+, Gd3+, respectively, and co-doped with Gd3+ and Eu2+ were prepared by high-temperature melting method. The transmission spectra, the excitation spectra, the emission spectra a...The phosphate glasses doped with Eu2+, Gd3+, respectively, and co-doped with Gd3+ and Eu2+ were prepared by high-temperature melting method. The transmission spectra, the excitation spectra, the emission spectra and the fluorescent decay time were investigated. The energy transfer process between Gd3+ and Eu2+ was studied. From the excitation spectra and the emission spectra of the phosphate glasses doped with Eu2+, we observed that the emission intensity of Eu2+ shows higher for 0.02 mol% Eu2+-doped phosphate glass. According to the excitation spectra and the emission spectra and the fluorescence decay curves, when the concentration of Eu2+ was 0.02 mol%, the optimal con- centration of Gd3+ was 0.3 tool%. Based on Dexter theory, it is shown that the energy transfer between Gd3+ and Eu2+ was nonradiation energy transfer by analyzing the energy-level diagram. The fluorescence decay curves of Gd3+ were expressed by the Inokuti-Hirayama's model and were used to analyze energy transfer mechanism between Gd3+ and Eu2+. And the energy transfer efficiency was also calculated.展开更多
A new way to improve the 1.53μm emission in Er3+/Yb3+ co-doped multicomponent phosphate glass was demonstrated by introducing silver nanoparticles (NPs) in rare-earth doped glass. The existence of Ag NPs was conf...A new way to improve the 1.53μm emission in Er3+/Yb3+ co-doped multicomponent phosphate glass was demonstrated by introducing silver nanoparticles (NPs) in rare-earth doped glass. The existence of Ag NPs was confirmed by absorption spectra and transmission electron microscopy (TEM) measurements. The homogeneous distribution of silver NPs could be observed by the TEM images. UV-Vis-NIR absorption spectra revealed that the surface plasmon band was centered at about 420 nm. The photoluminescence spectra of glass samples were used to investigate the effect of silver NPs on the fluorescence properties of Er3+. Efficient 1.53μm emis-sion was obtained in prepared samples when pumped at 980 nm laser diode (LD). The 1.53μm emission intensity could be enhanced 87% by doping 2 mol.% AgCl due to the increased localized field effect in the vicinity of NPs and the possible energy transfer from silver NPs to Er3+ions. Our present work may point out one way to enhance the gain coefficient of Er3+/Yb3+ co-doped glass fiber.展开更多
An efficient near-infrared (NIR) quantum cutting (QC) in Tm3+ and Yb3+ co-doped phosphate glasses was demonstrated, which involved the emission of two NIR photons from an absorbed visible photon via a cooperativ...An efficient near-infrared (NIR) quantum cutting (QC) in Tm3+ and Yb3+ co-doped phosphate glasses was demonstrated, which involved the emission of two NIR photons from an absorbed visible photon via a cooperative energy transfer (CET) from Tm3+ to Yb3+ ions. Judd-Ofelt (J-O) theory was used to calculate the intensity parameters ( 2 , 4 , 6 ), the radiative transition rates (Ar ), and radiative transition lifetime (τ rad ) of Tm3+ . Based on Inokuti-Hirayama's model, the energy transfer processes were studied and results indicated that the energy transfer of the electric dipole-dipole (Edd) was dominant in this system. Quantum efficiency related to Yb 3+ concentration was calculated, and the maximum QE efficiency reached 169.8%.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
We report on the fabrication and properties of an optical waveguide in Nd^3+-doped phosphate glass. The planar waveguide was obtained by 550-ke V proton implantation with a dose of 8.0×10^16 ions/cm^2. The proto...We report on the fabrication and properties of an optical waveguide in Nd^3+-doped phosphate glass. The planar waveguide was obtained by 550-ke V proton implantation with a dose of 8.0×10^16 ions/cm^2. The proton–glass interaction was simulated by the stopping and range of ions in matter(SRIM software). The characteristics of the waveguide including the refractive index profile and the near-field intensity distribution were studied by the reflectivity calculation method and the end-face coupling technique. The optical waveguide demonstrated multi-mode behavior at the wavelength of 632.8 nm.The propagation features of the proton-implanted Nd^(3+)-doped phosphate glass waveguide shows its potential to operate as an integrated photonic device.展开更多
Phosphate glasses of composition 48P<sub>2</sub>O<sub>5</sub>-30CaO-(22<span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span&g...Phosphate glasses of composition 48P<sub>2</sub>O<sub>5</sub>-30CaO-(22<span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>x)Na<sub>2</sub>O-xTiO<sub>2</sub> (with 0 < x ≤ 3, mol%) were prepared by direct melting at 1080<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">°</span></span></span>C ± 20<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">°</span></span></span>C. The chemical durability of these glasses shows an improvement when the Ti<span style="white-space:normal;">O</span><sub style="white-space:normal;">2</sub> 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<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">°</span></span></span>C for 48 h, indicates the appearance of a mixture of metaphosphate and pyrophosphate phases when the Ti<span style="white-space:normal;">O</span><sub style="white-space:normal;">2</sub> content varies from 0 to 2 mol%, the last become majority when the Ti<span style="white-space:normal;">O</span><sub style="white-space:normal;">2</sub> content rich 2 mol%. Nevertheless, when the Ti<span style="white-space:normal;">O</span><sub style="white-space:normal;">2</sub> 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 Ti<span style="white-space:normal;">O</span><sub style="white-space:normal;">2</sub> content increased at the expense of the Na<sub>2</sub>O content. An increase in the TiO<sub>2</sub> content beyond 2 mol% led to the formation of a larger number of crystallites of different sizes, dominated by small crystallite sizes assigned to majority isolated short orthophosphate groups. This phenomenon led to a decrease in chemical durability and seems to be the main cause promoting the bioactivity of glasses. The results of the bioactivity, after a test in an SBF physiological solution within 15 days, shows, both, the formation of hydroxyapatite and tricalcium phosphate layers, in addition to the layer Ca<sub>2</sub>P<sub>2</sub>O<sub>7</sub>, known by its bioactivity, in some samples. The results obtained on the glasses studied make them potential candidates for an application in tissue engineering.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
Glasses are prepared by sintering P2O5, ZnO and Ce2(C2O4)3 10H2O mixtures at 1 100 ℃ in air and then annealed at 400 ℃ for 10 hours. The obtained glasses are homogeneous, transparent and colorless. Emission and ex...Glasses are prepared by sintering P2O5, ZnO and Ce2(C2O4)3 10H2O mixtures at 1 100 ℃ in air and then annealed at 400 ℃ for 10 hours. The obtained glasses are homogeneous, transparent and colorless. Emission and excitation spectra are measured for the samples and the results show that the glasses contain Ce3+ trivalent cerium ions. The parameters of glass preparation obtained here may be adapted to preparing this type of glasses doped with other lanthanide ions, so as to study energy transfer phenomena and variation of radiative lifetime with refractive index due to local field effect.展开更多
The bio-glass in the Na2O-Ca2O-P2O5-SiO2 system involved in tins paper is highly bio-active. The hydrolization of this glass with calcium phosphate and low silica is studied. The structure-composition-property relatio...The bio-glass in the Na2O-Ca2O-P2O5-SiO2 system involved in tins paper is highly bio-active. The hydrolization of this glass with calcium phosphate and low silica is studied. The structure-composition-property relation of the glass is discussed by means of IR spectrum, DTA and SEM. This study shows that: (a)the structure of the glass is mainly chain-like or layer-like; (b) the glass is separated into a calcium phosphate-rich phase and a silica-rich phase; (c)the chuin- or layer-like structure and the separation hare advantages with hydrolization.展开更多
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.
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.
文摘Because of the influence of OH groups in phosphate glasses on the radiation of rare-earth ions, the laser performance is degraded. The laser efficiency and the small signal gain experiment of several phosphate glass samples have been done, the concentration of OH groups in glasses was calculated from the measured absorption coefficient at 3.47 μm. It is shown that the concentration of OH groups in phosphate glasses can seriously influence the laser output characteristics, and the OH groups have worse influence on the laser amplifier than laser oscillator.
基金Project supported by the Science and Higher Education (N N204 313937)
文摘Local structure and luminescent properties of lead phosphate glasses containing rare earth ions were studied. Optically active ions such as Eu^3+, Dy^3+, Tb^3+ and Er^3+ were chosen as dopants. The local structure was verified using X-ray diffraction and Fourier transform inflared (FT-IR) spectroscopy. The visible luminescence bands recorded for the studied samples corresponded to ^5D0→^7Fj (J=0÷4) transitions of Eu^3+, ^4F9/2→^6Hj/2 (J=11÷15) transitions of Dy^3+, ^5D3→^7FJ, (J'=1÷6) and ^5Da→^7FJ (J=3÷6) transitions of Tb^3+, and ^4S1/2→^4I15/2 transitions of Er^3+.
文摘Phosphate glass samples with various Yb2O3 and Er2O3 contents were synthesized by the conventional melt quenching technique and characterized by X-ray diffraction, IR absorption spectroscopy and Raman scattering spectroscopy. The absorption, emission spectra and fluorescence decay studies were carried out both at low and room temperatures. Results showed the existence of several sites occupied by the rare earth ions in the phosphate glass. Up-conversion and cooperative fluorescence were also discussed.
基金financially supported by the National Natural Science Foundation of China (Nos.61275180 and 51472125)the Natural Science Foundation of Ningbo City (No.2013A610126)+1 种基金the Outstanding Dissertation Growth Foundation of Ningbo University (No.PY2013009)the K.C.Wong Magna Fund in Ningbo University
文摘The phosphate glasses doped with Eu2+, Gd3+, respectively, and co-doped with Gd3+ and Eu2+ were prepared by high-temperature melting method. The transmission spectra, the excitation spectra, the emission spectra and the fluorescent decay time were investigated. The energy transfer process between Gd3+ and Eu2+ was studied. From the excitation spectra and the emission spectra of the phosphate glasses doped with Eu2+, we observed that the emission intensity of Eu2+ shows higher for 0.02 mol% Eu2+-doped phosphate glass. According to the excitation spectra and the emission spectra and the fluorescence decay curves, when the concentration of Eu2+ was 0.02 mol%, the optimal con- centration of Gd3+ was 0.3 tool%. Based on Dexter theory, it is shown that the energy transfer between Gd3+ and Eu2+ was nonradiation energy transfer by analyzing the energy-level diagram. The fluorescence decay curves of Gd3+ were expressed by the Inokuti-Hirayama's model and were used to analyze energy transfer mechanism between Gd3+ and Eu2+. And the energy transfer efficiency was also calculated.
基金Project supported by the High-level Personnel Special Support Program of Guangdong Province(2014TX01C087)China National Funds for Distinguished Young Scientists(61325024)+2 种基金Fundamental Research Funds for the Central Universities(2015ZP019)the Science and Technology Project of Guangdong(2015B090926010)Hi-tech Research and Development Program of China(2013AA031502)
文摘A new way to improve the 1.53μm emission in Er3+/Yb3+ co-doped multicomponent phosphate glass was demonstrated by introducing silver nanoparticles (NPs) in rare-earth doped glass. The existence of Ag NPs was confirmed by absorption spectra and transmission electron microscopy (TEM) measurements. The homogeneous distribution of silver NPs could be observed by the TEM images. UV-Vis-NIR absorption spectra revealed that the surface plasmon band was centered at about 420 nm. The photoluminescence spectra of glass samples were used to investigate the effect of silver NPs on the fluorescence properties of Er3+. Efficient 1.53μm emis-sion was obtained in prepared samples when pumped at 980 nm laser diode (LD). The 1.53μm emission intensity could be enhanced 87% by doping 2 mol.% AgCl due to the increased localized field effect in the vicinity of NPs and the possible energy transfer from silver NPs to Er3+ions. Our present work may point out one way to enhance the gain coefficient of Er3+/Yb3+ co-doped glass fiber.
基金Project supported by National Natural Science Foundation of China(61275180,50972061,51272109)Natural Science Founda tion of Zhejiang Province(Z4110072,R4100364)+1 种基金the Opening Foundation Opening Foundation of Zhejiang Provincial Top Key Disciplinesupported by the K.C.Wang Magna Fund in Ningbo University
文摘An efficient near-infrared (NIR) quantum cutting (QC) in Tm3+ and Yb3+ co-doped phosphate glasses was demonstrated, which involved the emission of two NIR photons from an absorbed visible photon via a cooperative energy transfer (CET) from Tm3+ to Yb3+ ions. Judd-Ofelt (J-O) theory was used to calculate the intensity parameters ( 2 , 4 , 6 ), the radiative transition rates (Ar ), and radiative transition lifetime (τ rad ) of Tm3+ . Based on Inokuti-Hirayama's model, the energy transfer processes were studied and results indicated that the energy transfer of the electric dipole-dipole (Edd) was dominant in this system. Quantum efficiency related to Yb 3+ concentration was calculated, and the maximum QE efficiency reached 169.8%.
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.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11405041 and 61475189)NUPTSF,China(Grant Nos.NY214159,NY215007,and NY215113)
文摘We report on the fabrication and properties of an optical waveguide in Nd^3+-doped phosphate glass. The planar waveguide was obtained by 550-ke V proton implantation with a dose of 8.0×10^16 ions/cm^2. The proton–glass interaction was simulated by the stopping and range of ions in matter(SRIM software). The characteristics of the waveguide including the refractive index profile and the near-field intensity distribution were studied by the reflectivity calculation method and the end-face coupling technique. The optical waveguide demonstrated multi-mode behavior at the wavelength of 632.8 nm.The propagation features of the proton-implanted Nd^(3+)-doped phosphate glass waveguide shows its potential to operate as an integrated photonic device.
文摘Phosphate glasses of composition 48P<sub>2</sub>O<sub>5</sub>-30CaO-(22<span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>x)Na<sub>2</sub>O-xTiO<sub>2</sub> (with 0 < x ≤ 3, mol%) were prepared by direct melting at 1080<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">°</span></span></span>C ± 20<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">°</span></span></span>C. The chemical durability of these glasses shows an improvement when the Ti<span style="white-space:normal;">O</span><sub style="white-space:normal;">2</sub> 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<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">°</span></span></span>C for 48 h, indicates the appearance of a mixture of metaphosphate and pyrophosphate phases when the Ti<span style="white-space:normal;">O</span><sub style="white-space:normal;">2</sub> content varies from 0 to 2 mol%, the last become majority when the Ti<span style="white-space:normal;">O</span><sub style="white-space:normal;">2</sub> content rich 2 mol%. Nevertheless, when the Ti<span style="white-space:normal;">O</span><sub style="white-space:normal;">2</sub> 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 Ti<span style="white-space:normal;">O</span><sub style="white-space:normal;">2</sub> content increased at the expense of the Na<sub>2</sub>O content. An increase in the TiO<sub>2</sub> content beyond 2 mol% led to the formation of a larger number of crystallites of different sizes, dominated by small crystallite sizes assigned to majority isolated short orthophosphate groups. This phenomenon led to a decrease in chemical durability and seems to be the main cause promoting the bioactivity of glasses. The results of the bioactivity, after a test in an SBF physiological solution within 15 days, shows, both, the formation of hydroxyapatite and tricalcium phosphate layers, in addition to the layer Ca<sub>2</sub>P<sub>2</sub>O<sub>7</sub>, known by its bioactivity, in some samples. The results obtained on the glasses studied make them potential candidates for an application in tissue engineering.
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.
基金Funded by National Natural Science Foundation of China(Nos.10874253 and 11111120060)Education Committe of Chongqing(No. KJ090520)
文摘Glasses are prepared by sintering P2O5, ZnO and Ce2(C2O4)3 10H2O mixtures at 1 100 ℃ in air and then annealed at 400 ℃ for 10 hours. The obtained glasses are homogeneous, transparent and colorless. Emission and excitation spectra are measured for the samples and the results show that the glasses contain Ce3+ trivalent cerium ions. The parameters of glass preparation obtained here may be adapted to preparing this type of glasses doped with other lanthanide ions, so as to study energy transfer phenomena and variation of radiative lifetime with refractive index due to local field effect.
文摘The bio-glass in the Na2O-Ca2O-P2O5-SiO2 system involved in tins paper is highly bio-active. The hydrolization of this glass with calcium phosphate and low silica is studied. The structure-composition-property relation of the glass is discussed by means of IR spectrum, DTA and SEM. This study shows that: (a)the structure of the glass is mainly chain-like or layer-like; (b) the glass is separated into a calcium phosphate-rich phase and a silica-rich phase; (c)the chuin- or layer-like structure and the separation hare advantages with hydrolization.