The possibility of identifying gunshot residue (GSR) particles produced by non-toxic primers containing only titanium and zinc is a very difficult task using SEM/EDX analysis employed in the analysis of GSR originatin...The possibility of identifying gunshot residue (GSR) particles produced by non-toxic primers containing only titanium and zinc is a very difficult task using SEM/EDX analysis employed in the analysis of GSR originating from primers containing lead, barium and antimony. However, Bauer et al. demonstrated that non-toxic (TieZn) primers form a TiZn2O4 spinel crystalline structure using SEM/EDX with EBSD (Electron Back Scatter Diffraction) and TKD (Transmission Kikuchi Diffraction), whereas GSR originating from gadolinium-doped TieZn primers form a non-crystalline glass phase. Here, a possible explanation of these different phenomena is hypothesized.展开更多
BN/La-Al-Si-O composite ceramics were fabricated by hot-pressed sintering using hexagonal boron nitride(h-BN),lanthanum oxide(La_(2)O_(3)),aluminia(Al_(2)O_(3)),and amorphous silica(SiO_(2))as the raw materials.The ef...BN/La-Al-Si-O composite ceramics were fabricated by hot-pressed sintering using hexagonal boron nitride(h-BN),lanthanum oxide(La_(2)O_(3)),aluminia(Al_(2)O_(3)),and amorphous silica(SiO_(2))as the raw materials.The effects of sintering temperature on microstructural evolution,bulk density,apparent porosity,and mechanical properties of the h-BN composite ceramics were investigated.The results indicated that La-Al-Si-O liquid phase was formed during sintering process,which provided an environment for the growth of h-BN grains.With increasing sintering temperature,the cristobalite phase precipitation and h-BN grain growth occurred at the same time,which had a significant influence on the densification and mechanical properties of h-BN composite ceramics.The best mechanical properties of BN/La-Al-Si-O composite ceramics were obtained under the sintering temperature of 1700℃.The elastic modulus,flexural strength,and fracture toughness were 80.5 GPa,266.4 MPa,and 3.25 MPa·m^(1/2),respectively.展开更多
XRD,TEM,ED,and NMR analyzed four types of blast furnace slags (BFS) with different structures in this paper. The composition requirement for phase separation in BFS glass phase was then put forward,that is the composi...XRD,TEM,ED,and NMR analyzed four types of blast furnace slags (BFS) with different structures in this paper. The composition requirement for phase separation in BFS glass phase was then put forward,that is the composition of slag locates in the coexisting phase region of melilite and any silicate mineral with Q0 units. The special structure of melilite units,a 5-membered ring with high degree of polymerization (DOP),plays a key role in the formation of phase separation. In BFS system,one with chemical composition of larger ratio of (CaO + MgO/(SiO2 + Al2O3) would be more promising to meet the requirement for phase separation.展开更多
The fractal and spinodal decomposition models combined Monte Carlo method were used in computer simulation of phase separation from CaO MgO Fe 2O 3 Al 2O 3 SiO 2 glass. The fractal dimension was applied to quantitativ...The fractal and spinodal decomposition models combined Monte Carlo method were used in computer simulation of phase separation from CaO MgO Fe 2O 3 Al 2O 3 SiO 2 glass. The fractal dimension was applied to quantitative analysis. The mechanism of phase separation was investigated. The results showed that the fractal dimensions and simulated micrographs of phase separation were in good agreement with the experimental results. And the mechanism of phase separation was spinodal decomposition.展开更多
Amorphous materials are ubiquitous and widely used in human society, yet their structures are far from being fully understood. Metallic glasses, a new class of amorphous materials, have attracted a great deal of inter...Amorphous materials are ubiquitous and widely used in human society, yet their structures are far from being fully understood. Metallic glasses, a new class of amorphous materials, have attracted a great deal of interests due to their exceptional properties. In recent years, our understanding of metallic glasses increases dramatically, thanks to the development of advanced instrumentation, such as in situ x-ray and neutron scattering. In this article, we provide a brief review of recent progress in study of the structure of metallic glasses. In particular, we will emphasize, from the scattering perspective, the multiscale structures of metallic glasses, i.e., short-to-medium range atomic packing, and phase transitions in the supercooled liquid region, e.g., crystallization and liquid-to-liquid phase transition. We will also discuss, based on the understanding of their structures and phase stability, the mechanical and magnetic properties of metallic glasses.展开更多
Based on the premise that the addition of glass beads （GB） could hardly influence the linear viscoelasticity in low frequency （ω） region for homogeneous polymer systems, the dynamic rheological behaviors of unfil...Based on the premise that the addition of glass beads （GB） could hardly influence the linear viscoelasticity in low frequency （ω） region for homogeneous polymer systems, the dynamic rheological behaviors of unfilled and filled poly（methyl methyacrylate） （PMMA）/poly（styrene-co-acrylonitrile） （SAN） blends were studied in order to explore the effect of GB on the phase-separation of binary polymer matrix. Results show that GB has an induced effect on the phase-separation, which embodies that the phase-separation temperature （Ts） of PMMA/SAN blend filled with GB is lower than that of the unfilled system. The higher content of GB, the higher is the ＂secondary plateau＂ of ω in the terminal region of storage modulus （G＇） versus ω plot. The ＂secondary plateau＂ appearing in the terminal region is attributed to the phase-separation of PMMA/SAN blends and it becomes more fiat for filled polymer blends under the same conditions. However, it is suggested that this kind of ＂induced effect＂ is related to the GB content; the higher content of GB particles might enhance the interaction between the particles and polymer matrix. Moreover, it is found that the addition of GB also has an influence more or less on the morphology and domain size of polymer matrix. It is believed that the plot of dynamic viscosity （η＇） versus the loss viscosity （η＂） is sensitive to examine the effect induced by GB on the phase-separation of binary polymer matrix.展开更多
Based on the construction of TTT diagrams by isothermal DSC measurements, the thermal stabilities of Zr65Cu27.5Al7.5 glassy alloys containing 0.68% and 0.06% [O] (molar fraction) were compared. The changing tendencies...Based on the construction of TTT diagrams by isothermal DSC measurements, the thermal stabilities of Zr65Cu27.5Al7.5 glassy alloys containing 0.68% and 0.06% [O] (molar fraction) were compared. The changing tendencies of the thermal stabilities reflected in the TTT-diagrams were validated by XRD analyses and TEM observations. The crystallization kinetic characteristics of oxygen-induced I-phase and Zr2Cu phase in Zr65Cu27.5Al7.5 glassy alloy were discussed. It is found that oxygen promotes the precipitation of I-phase and retards the formation of Zr2Cu phase. If the pre-crystallization event for oxygen-induced I-phase is permitted and the main-crystallization event for Zr2Cu phase is taken as the thermal stability criterion, the alloy with higher oxygen content has longer onset time for crystallization within a rather large supercooling temperature range. The possibility for the preparation of Zr65Cu27.5Al7.5 glassy alloy-based composite containing oxygen-induced I-phase was also forecasted.展开更多
Uniform crystalline TiO2 thin films were coated on silica glass fibers by liquid phase deposition from aqueous solution of ammonium hexafluorotitanate at low temperature. TiO2 thin films and nanopowders were prepared ...Uniform crystalline TiO2 thin films were coated on silica glass fibers by liquid phase deposition from aqueous solution of ammonium hexafluorotitanate at low temperature. TiO2 thin films and nanopowders were prepared by adding H3BO3 into （NH4）2TiF6 solution supersaturated with anatase nano-crystalline TiO2 at 40 ℃. The effects of the deposition conditions on the surface morphology, section morphology, thickness of the deposited TiO2 thin films were investigated. The results indicate that the growth rate and particle size of the thin films were controlled by both the deposition conditions and the amount of anatase nano-crystalline TiO2.展开更多
A 488 nm continuous wave （CW） laser was employed in Raman spectrometer to both induce and characterize phase transformation in chalcogenide glasses. Laser-induced Raman inactive changes, structural evolution, and cr...A 488 nm continuous wave （CW） laser was employed in Raman spectrometer to both induce and characterize phase transformation in chalcogenide glasses. Laser-induced Raman inactive changes, structural evolution, and crystallization were observed at laser-irradiated region in GeS2-Sb2S3 glasses. The composition dependence of laser-induced phase transformation was discussed in terms of thermal stability and microstructural modification. It is strongly suggested from these results that fabrication of passive and active chalcogenide glass waveguides, such as refractive index change and nonlinear optical crystal line, is controllable by selecting appropriate glass composition, and convenient by using common CW lasers.展开更多
The phase transformation of R2O-CaO-SiO2-F system glass-ceramics with various additions of K2O and F was investigated by DTA, XRD, SEM and other techniques. The crystallization and the microstructure of the obtained g...The phase transformation of R2O-CaO-SiO2-F system glass-ceramics with various additions of K2O and F was investigated by DTA, XRD, SEM and other techniques. The crystallization and the microstructure of the obtained glass-ceramics were also evaluated. The phase separation occurred in CN1 specimen after being quenched in water, but phase separation did not appear in other quenched specimens with the content of K2O and F increasing obviously, showing K2O and F modified the structure of the glass-forming melts. The increase of K2O and F resulted in the reduction of phase separation and the enhancement of crystallization. The main crystalline phase formed after heat-treatment was canasite and CaF2. The microstructures of the crystalline specimens consisted of interlocking radial and granular crystals. Moreover, the crystallinity was increased as the content of K2O was increased from 0.07 mol to 0.08 mol.展开更多
In this work, network former SiO_2 and network intermediate Al_2O_3 were introduced into typical low-melting binary compositions CaO·B_2O_3, CaO·2B_2O_3, and BaO·B_2O_3 via an aqueous solid-state suspen...In this work, network former SiO_2 and network intermediate Al_2O_3 were introduced into typical low-melting binary compositions CaO·B_2O_3, CaO·2B_2O_3, and BaO·B_2O_3 via an aqueous solid-state suspension milling route. Accordingly, multiple-phase aluminosilicate glass-ceramics were directly obtained via liquid-phase sintering at temperatures below 950°C. On the basis of liquid-phase sintering theory, mineral-phase evolutions and glass-phase formations were systematically investigated in a wide MO–SiO_2–Al_2O_3–B_2O_3(M = Ca, Ba) composition range. The results indicate that major mineral phases of the aluminosilicate glass-ceramics are Al_(20)B_4O_(36), CaAl_2Si_2O_8, and BaAl_2Si_2O_8 and that the glass-ceramic materials are characterized by dense microstructures and excellent dielectric properties.展开更多
In this paper the experimental results associated until the phase separation and nucleation and crystallization of chalcogenidc glasses are described. Experi-ments demonstrate that the phas separation may be affected ...In this paper the experimental results associated until the phase separation and nucleation and crystallization of chalcogenidc glasses are described. Experi-ments demonstrate that the phas separation may be affected by small amount of additives. It has been found that some chalcogenide glasses could be converted into glass-ceramics without phase separation. The different mechanisms of nucleated crystallization of chalcogenide glasses are discussed and propossed.展开更多
This work mainly involved the preparation of a nano-scale form-stable phase change material（PCM） consisting of capric and myristic acid（CA-MA） binary eutectic acting as thermal absorbing material and nano silicon ...This work mainly involved the preparation of a nano-scale form-stable phase change material（PCM） consisting of capric and myristic acid（CA-MA） binary eutectic acting as thermal absorbing material and nano silicon dioxide（nano-SiO_2） serving as the supporting material. Industrial water glass for preparation of the nano silicon dioxide matrix and CA-MA eutectic mixture were compounded by single-step sol-gel method with the silane coupling agent. The morphology, chemical characterization and form stability property of the composite PCM were investigated by transmission electron microscopy（TEM）, scanning electron microscopy（SEM）, Fourier-transform infrared（FT-IR） spectroscopy and polarizing microscopy（POM）. It was indicated that the average diameter of the composite PCM particle ranged from 30-100 nm. The CA-MA eutectic was immobilized in the network pores constructed by the Si-O bonds so that the composite PCM was allowed no liquid leakage above the melting temperature of the CA-MA eutectic. Differential scanning calorimetry（DSC） and thermogravimetric analysis（TGA） measurement were conducted to investigate the thermal properties and stability of the composite PCM. From the measurement results, the mass fraction of the CA-MA eutectic in the composite PCM was about 40%. The phase change temperature and latent heat of the composite were determined to be 21.15 ℃ and 55.67 J/g, respectively. Meanwhile, thermal conductivity of the composite was measured to be 0.208 W·m^（-1）·K^（-1） by using the transient hot-wire method. The composite PCM was able to maintain the surrounding temperature close to its phase change temperature and behaved well in thermalregulated performance which was verified by the heat storage-release experiment. This kind of form-stable PCM was supposed to complete thermal insulation even temperature regulation by the dual effect of relatively low thermal conductivity and phase change thermal storage-release properties. So it can be formulated that the nanoscale CA-MA/SiO_2 composite PCM with the form-stable property, good thermal storage capacity and relatively low thermal conductivity can be applied for energy conservation as a kind of thermal functional material.展开更多
Anderson localization has been realized in several different systems over the years. In this paper we describe a rather unique manifestation of the phenomenon occurring in a two-phase glass composition that guides lig...Anderson localization has been realized in several different systems over the years. In this paper we describe a rather unique manifestation of the phenomenon occurring in a two-phase glass composition that guides light. The glasses are a borate or alkali borosilicate composition that when heated separates into two distinct phases of different compositions, a high index phase and a low index phase. When the glass is heated with a specific thermal schedule to develop the phase separation it is then drawn into a rod or fiber, the particulate phase forms elongated strands resulting in a random cross-sectional refractive index pattern. This pattern of refractive index is maintained along the length producing a light guiding behavior over a significant distance that we propose is a manifestation of an Anderson localization phenomenon.展开更多
We investigate the co-propagation of a strong pump beam and a weak signal beam in lead glass, and find that the large phase shift of the strongly nonlocal spatial optical soliton （SNSOS） can be realized via cross-ph...We investigate the co-propagation of a strong pump beam and a weak signal beam in lead glass, and find that the large phase shift of the strongly nonlocal spatial optical soliton （SNSOS） can be realized via cross-phase modulation. The theoretical study suggests a synchronous propagation of the pump SNSOS and the signal SNSOS under the required initial condition. A π-phase shift of the signal SNSOS is experimentally obtained by changing the power of the pump SNSOS by about 13 mW around the soliton critical power, which agrees qualitatively with our theoretical prediction. The ratio of the phase shift rate of the signal SNSOS to that of the pump SNSOS shows a close match to the reciprocal of the ratio between their wavelengths.展开更多
We systematically investigate the effect of pressure on the magnetic properties of GdCo2B2 on the basis of alternating current（AC） susceptibility,AC heat capacity and electrical resistivity measurements under pressu...We systematically investigate the effect of pressure on the magnetic properties of GdCo2B2 on the basis of alternating current（AC） susceptibility,AC heat capacity and electrical resistivity measurements under pressures up to 2.2 GPa.A detailed magnetic phase diagram under pressure is determined.GdCo2B2 exhibits three anomalies that apparently reflect magnetic phase transitions,respectively,at temperatures TC= 20.5 K,T1= 18.0 K and TN= 11.5 K under ambient pressure.Under pressures up to 2.2 GPa,these anomalies are observed to slightly increase at TCand T1,and they coincide with each other above 1.6 GPa.Conversely,they decrease at TN and disappear under pressures higher than 1.4 GPa.The results indicate that the low-temperature magnetic phases can be easily suppressed by pressure.Moreover,the spin-glass-like behavior of GdCo2B2 is examined in terms of magnetization,aging effect and frequency dependence of AC susceptibility.A separation between the zero-field-cooled（ZFC） and field-cooled（FC） magnetization curves becomes evident at a low magnetic field of 0.001 T.A long-time relaxation behavior is observed at 4 K.The freezing temperature Tfincreases with frequency increasing.展开更多
Glass fibers, cc diameter of 350 mum to 500 mum, were made of glasses with an initial composition of 66. 55iO(2) - 25B(2)O(2) - 8. 5 Na2O. Being heated at 580 C for 24 hours and leached in HCl solution at 90 C: for 12...Glass fibers, cc diameter of 350 mum to 500 mum, were made of glasses with an initial composition of 66. 55iO(2) - 25B(2)O(2) - 8. 5 Na2O. Being heated at 580 C for 24 hours and leached in HCl solution at 90 C: for 12 hours, the glass fibers were made into porous glass fibers, pore size in the range 25nm to 35nm. The influence of the glass composition cold condition on glass phase separation Is discussed. The transparence of the porous glass fibers before and after being charged with sensitive reagents and the anti-resolve characteristics of sensitized reagent charged were also studied. The results have shown that the transparence of porous glass fibers after being charged with sensitive reagents and the anti-resolve characteristics of sensitive reagents charged in the materials were very well. By combining with special sensitive reagents, the porous glass fibers could be made into a series of fiber optic chemical sensors with different characteristics.展开更多
In order to improve the properties of alumina-carbon refractories,specimens were prepared using white fused corundum,zirconia-mullite and flake graphite as the raw materials,phenolic resin as the binder,adding differe...In order to improve the properties of alumina-carbon refractories,specimens were prepared using white fused corundum,zirconia-mullite and flake graphite as the raw materials,phenolic resin as the binder,adding different mass fractions(1.5%,2.0%,and 2.5%,respectively)of glass dust,cold isostatic pressing by 120 MPa,drying and firing at 900℃for 3 h.Effects of the glass dust addition on the apparent porosity,bulk density,cold modulus of rupture,hot modulus of rupture and thermal shock resistance were studied.The results show that the cold modulus of rupture of the specimens is improved significantly as the results of glass dust accelerating sintering.However,the hot modulus of rupture decreases.As the glass phase buffers the strain produced by thermal shock,the thermal shock resistance of alumina-carbon specimens is improved,especially for low carbon alumina-carbon materials.展开更多
文摘The possibility of identifying gunshot residue (GSR) particles produced by non-toxic primers containing only titanium and zinc is a very difficult task using SEM/EDX analysis employed in the analysis of GSR originating from primers containing lead, barium and antimony. However, Bauer et al. demonstrated that non-toxic (TieZn) primers form a TiZn2O4 spinel crystalline structure using SEM/EDX with EBSD (Electron Back Scatter Diffraction) and TKD (Transmission Kikuchi Diffraction), whereas GSR originating from gadolinium-doped TieZn primers form a non-crystalline glass phase. Here, a possible explanation of these different phenomena is hypothesized.
基金This study was financially supported by the National Key Research and Development Program of China(No.2017YFB0310400)the National Natural Science Foundation of China(Nos.52072089,51672060,and 51832002).
文摘BN/La-Al-Si-O composite ceramics were fabricated by hot-pressed sintering using hexagonal boron nitride(h-BN),lanthanum oxide(La_(2)O_(3)),aluminia(Al_(2)O_(3)),and amorphous silica(SiO_(2))as the raw materials.The effects of sintering temperature on microstructural evolution,bulk density,apparent porosity,and mechanical properties of the h-BN composite ceramics were investigated.The results indicated that La-Al-Si-O liquid phase was formed during sintering process,which provided an environment for the growth of h-BN grains.With increasing sintering temperature,the cristobalite phase precipitation and h-BN grain growth occurred at the same time,which had a significant influence on the densification and mechanical properties of h-BN composite ceramics.The best mechanical properties of BN/La-Al-Si-O composite ceramics were obtained under the sintering temperature of 1700℃.The elastic modulus,flexural strength,and fracture toughness were 80.5 GPa,266.4 MPa,and 3.25 MPa·m^(1/2),respectively.
基金supported by the National Natural Science Foundation of China (Grant No.50954004)the National Science & Technology Pillar Program of China (Grant No.2007AA03Z529)
文摘XRD,TEM,ED,and NMR analyzed four types of blast furnace slags (BFS) with different structures in this paper. The composition requirement for phase separation in BFS glass phase was then put forward,that is the composition of slag locates in the coexisting phase region of melilite and any silicate mineral with Q0 units. The special structure of melilite units,a 5-membered ring with high degree of polymerization (DOP),plays a key role in the formation of phase separation. In BFS system,one with chemical composition of larger ratio of (CaO + MgO/(SiO2 + Al2O3) would be more promising to meet the requirement for phase separation.
文摘The fractal and spinodal decomposition models combined Monte Carlo method were used in computer simulation of phase separation from CaO MgO Fe 2O 3 Al 2O 3 SiO 2 glass. The fractal dimension was applied to quantitative analysis. The mechanism of phase separation was investigated. The results showed that the fractal dimensions and simulated micrographs of phase separation were in good agreement with the experimental results. And the mechanism of phase separation was spinodal decomposition.
基金supported by Shenzhen Science and Technology Innovation Commission of China(Grant No.R-IND8701)the Croucher Foundation(Project No.City U 9500020)+2 种基金partially supported by the Fundamental Research Funds for the Central Universities of China(Grant No.30915015103)the National Natural Science Foundation of China(Grant No.51501090)partially supported by the National Natural Science Foundation of China(Grant No.51571170)
文摘Amorphous materials are ubiquitous and widely used in human society, yet their structures are far from being fully understood. Metallic glasses, a new class of amorphous materials, have attracted a great deal of interests due to their exceptional properties. In recent years, our understanding of metallic glasses increases dramatically, thanks to the development of advanced instrumentation, such as in situ x-ray and neutron scattering. In this article, we provide a brief review of recent progress in study of the structure of metallic glasses. In particular, we will emphasize, from the scattering perspective, the multiscale structures of metallic glasses, i.e., short-to-medium range atomic packing, and phase transitions in the supercooled liquid region, e.g., crystallization and liquid-to-liquid phase transition. We will also discuss, based on the understanding of their structures and phase stability, the mechanical and magnetic properties of metallic glasses.
基金This project was supported by the National Natural Science Foundation of China(No.20304014)the Special Funds for National Science Funds for Distinguished Young Scholars(No.50125312).
文摘Based on the premise that the addition of glass beads （GB） could hardly influence the linear viscoelasticity in low frequency （ω） region for homogeneous polymer systems, the dynamic rheological behaviors of unfilled and filled poly（methyl methyacrylate） （PMMA）/poly（styrene-co-acrylonitrile） （SAN） blends were studied in order to explore the effect of GB on the phase-separation of binary polymer matrix. Results show that GB has an induced effect on the phase-separation, which embodies that the phase-separation temperature （Ts） of PMMA/SAN blend filled with GB is lower than that of the unfilled system. The higher content of GB, the higher is the ＂secondary plateau＂ of ω in the terminal region of storage modulus （G＇） versus ω plot. The ＂secondary plateau＂ appearing in the terminal region is attributed to the phase-separation of PMMA/SAN blends and it becomes more fiat for filled polymer blends under the same conditions. However, it is suggested that this kind of ＂induced effect＂ is related to the GB content; the higher content of GB particles might enhance the interaction between the particles and polymer matrix. Moreover, it is found that the addition of GB also has an influence more or less on the morphology and domain size of polymer matrix. It is believed that the plot of dynamic viscosity （η＇） versus the loss viscosity （η＂） is sensitive to examine the effect induced by GB on the phase-separation of binary polymer matrix.
基金Project(50671076) supported by the National Natural Science Foundation of China
文摘Based on the construction of TTT diagrams by isothermal DSC measurements, the thermal stabilities of Zr65Cu27.5Al7.5 glassy alloys containing 0.68% and 0.06% [O] (molar fraction) were compared. The changing tendencies of the thermal stabilities reflected in the TTT-diagrams were validated by XRD analyses and TEM observations. The crystallization kinetic characteristics of oxygen-induced I-phase and Zr2Cu phase in Zr65Cu27.5Al7.5 glassy alloy were discussed. It is found that oxygen promotes the precipitation of I-phase and retards the formation of Zr2Cu phase. If the pre-crystallization event for oxygen-induced I-phase is permitted and the main-crystallization event for Zr2Cu phase is taken as the thermal stability criterion, the alloy with higher oxygen content has longer onset time for crystallization within a rather large supercooling temperature range. The possibility for the preparation of Zr65Cu27.5Al7.5 glassy alloy-based composite containing oxygen-induced I-phase was also forecasted.
文摘Uniform crystalline TiO2 thin films were coated on silica glass fibers by liquid phase deposition from aqueous solution of ammonium hexafluorotitanate at low temperature. TiO2 thin films and nanopowders were prepared by adding H3BO3 into （NH4）2TiF6 solution supersaturated with anatase nano-crystalline TiO2 at 40 ℃. The effects of the deposition conditions on the surface morphology, section morphology, thickness of the deposited TiO2 thin films were investigated. The results indicate that the growth rate and particle size of the thin films were controlled by both the deposition conditions and the amount of anatase nano-crystalline TiO2.
基金Funded in part by the the International Science&Technology Cooperation Program of China(No.2011DFA12040)State Key Laboratory of Silicate Materials for Architectures(Wuhan University of Technology)(No.SYSJJ2013-03)sponsored by K.C.Wong Magna Fund in Ningbo University
文摘A 488 nm continuous wave （CW） laser was employed in Raman spectrometer to both induce and characterize phase transformation in chalcogenide glasses. Laser-induced Raman inactive changes, structural evolution, and crystallization were observed at laser-irradiated region in GeS2-Sb2S3 glasses. The composition dependence of laser-induced phase transformation was discussed in terms of thermal stability and microstructural modification. It is strongly suggested from these results that fabrication of passive and active chalcogenide glass waveguides, such as refractive index change and nonlinear optical crystal line, is controllable by selecting appropriate glass composition, and convenient by using common CW lasers.
文摘The phase transformation of R2O-CaO-SiO2-F system glass-ceramics with various additions of K2O and F was investigated by DTA, XRD, SEM and other techniques. The crystallization and the microstructure of the obtained glass-ceramics were also evaluated. The phase separation occurred in CN1 specimen after being quenched in water, but phase separation did not appear in other quenched specimens with the content of K2O and F increasing obviously, showing K2O and F modified the structure of the glass-forming melts. The increase of K2O and F resulted in the reduction of phase separation and the enhancement of crystallization. The main crystalline phase formed after heat-treatment was canasite and CaF2. The microstructures of the crystalline specimens consisted of interlocking radial and granular crystals. Moreover, the crystallinity was increased as the content of K2O was increased from 0.07 mol to 0.08 mol.
基金financially supported by the Fundamental Research Funds for the Central Universities of China(No.A0920502051513-5)
文摘In this work, network former SiO_2 and network intermediate Al_2O_3 were introduced into typical low-melting binary compositions CaO·B_2O_3, CaO·2B_2O_3, and BaO·B_2O_3 via an aqueous solid-state suspension milling route. Accordingly, multiple-phase aluminosilicate glass-ceramics were directly obtained via liquid-phase sintering at temperatures below 950°C. On the basis of liquid-phase sintering theory, mineral-phase evolutions and glass-phase formations were systematically investigated in a wide MO–SiO_2–Al_2O_3–B_2O_3(M = Ca, Ba) composition range. The results indicate that major mineral phases of the aluminosilicate glass-ceramics are Al_(20)B_4O_(36), CaAl_2Si_2O_8, and BaAl_2Si_2O_8 and that the glass-ceramic materials are characterized by dense microstructures and excellent dielectric properties.
文摘In this paper the experimental results associated until the phase separation and nucleation and crystallization of chalcogenidc glasses are described. Experi-ments demonstrate that the phas separation may be affected by small amount of additives. It has been found that some chalcogenide glasses could be converted into glass-ceramics without phase separation. The different mechanisms of nucleated crystallization of chalcogenide glasses are discussed and propossed.
基金Funded by the National Natural Science Foundation of China(No.51308275)Natural Science Foundation of Liaoning Province(No.SY2016004)the Colleges and Universities Excellent Talents Supporting Plan Program of Liaoning Province(No.LJQ2015049)
文摘This work mainly involved the preparation of a nano-scale form-stable phase change material（PCM） consisting of capric and myristic acid（CA-MA） binary eutectic acting as thermal absorbing material and nano silicon dioxide（nano-SiO_2） serving as the supporting material. Industrial water glass for preparation of the nano silicon dioxide matrix and CA-MA eutectic mixture were compounded by single-step sol-gel method with the silane coupling agent. The morphology, chemical characterization and form stability property of the composite PCM were investigated by transmission electron microscopy（TEM）, scanning electron microscopy（SEM）, Fourier-transform infrared（FT-IR） spectroscopy and polarizing microscopy（POM）. It was indicated that the average diameter of the composite PCM particle ranged from 30-100 nm. The CA-MA eutectic was immobilized in the network pores constructed by the Si-O bonds so that the composite PCM was allowed no liquid leakage above the melting temperature of the CA-MA eutectic. Differential scanning calorimetry（DSC） and thermogravimetric analysis（TGA） measurement were conducted to investigate the thermal properties and stability of the composite PCM. From the measurement results, the mass fraction of the CA-MA eutectic in the composite PCM was about 40%. The phase change temperature and latent heat of the composite were determined to be 21.15 ℃ and 55.67 J/g, respectively. Meanwhile, thermal conductivity of the composite was measured to be 0.208 W·m^（-1）·K^（-1） by using the transient hot-wire method. The composite PCM was able to maintain the surrounding temperature close to its phase change temperature and behaved well in thermalregulated performance which was verified by the heat storage-release experiment. This kind of form-stable PCM was supposed to complete thermal insulation even temperature regulation by the dual effect of relatively low thermal conductivity and phase change thermal storage-release properties. So it can be formulated that the nanoscale CA-MA/SiO_2 composite PCM with the form-stable property, good thermal storage capacity and relatively low thermal conductivity can be applied for energy conservation as a kind of thermal functional material.
文摘Anderson localization has been realized in several different systems over the years. In this paper we describe a rather unique manifestation of the phenomenon occurring in a two-phase glass composition that guides light. The glasses are a borate or alkali borosilicate composition that when heated separates into two distinct phases of different compositions, a high index phase and a low index phase. When the glass is heated with a specific thermal schedule to develop the phase separation it is then drawn into a rod or fiber, the particulate phase forms elongated strands resulting in a random cross-sectional refractive index pattern. This pattern of refractive index is maintained along the length producing a light guiding behavior over a significant distance that we propose is a manifestation of an Anderson localization phenomenon.
基金Project supported by the National Natural Science Foundation of China(Grant No.11274125)
文摘We investigate the co-propagation of a strong pump beam and a weak signal beam in lead glass, and find that the large phase shift of the strongly nonlocal spatial optical soliton （SNSOS） can be realized via cross-phase modulation. The theoretical study suggests a synchronous propagation of the pump SNSOS and the signal SNSOS under the required initial condition. A π-phase shift of the signal SNSOS is experimentally obtained by changing the power of the pump SNSOS by about 13 mW around the soliton critical power, which agrees qualitatively with our theoretical prediction. The ratio of the phase shift rate of the signal SNSOS to that of the pump SNSOS shows a close match to the reciprocal of the ratio between their wavelengths.
基金Project supported by JSPS KAKENHI(Grant No.24540366,Grant-in-Aid for Scientific Research(C))
文摘We systematically investigate the effect of pressure on the magnetic properties of GdCo2B2 on the basis of alternating current（AC） susceptibility,AC heat capacity and electrical resistivity measurements under pressures up to 2.2 GPa.A detailed magnetic phase diagram under pressure is determined.GdCo2B2 exhibits three anomalies that apparently reflect magnetic phase transitions,respectively,at temperatures TC= 20.5 K,T1= 18.0 K and TN= 11.5 K under ambient pressure.Under pressures up to 2.2 GPa,these anomalies are observed to slightly increase at TCand T1,and they coincide with each other above 1.6 GPa.Conversely,they decrease at TN and disappear under pressures higher than 1.4 GPa.The results indicate that the low-temperature magnetic phases can be easily suppressed by pressure.Moreover,the spin-glass-like behavior of GdCo2B2 is examined in terms of magnetization,aging effect and frequency dependence of AC susceptibility.A separation between the zero-field-cooled（ZFC） and field-cooled（FC） magnetization curves becomes evident at a low magnetic field of 0.001 T.A long-time relaxation behavior is observed at 4 K.The freezing temperature Tfincreases with frequency increasing.
基金Funded by Natural Science Foundation of China(No.69477021)
文摘Glass fibers, cc diameter of 350 mum to 500 mum, were made of glasses with an initial composition of 66. 55iO(2) - 25B(2)O(2) - 8. 5 Na2O. Being heated at 580 C for 24 hours and leached in HCl solution at 90 C: for 12 hours, the glass fibers were made into porous glass fibers, pore size in the range 25nm to 35nm. The influence of the glass composition cold condition on glass phase separation Is discussed. The transparence of the porous glass fibers before and after being charged with sensitive reagents and the anti-resolve characteristics of sensitized reagent charged were also studied. The results have shown that the transparence of porous glass fibers after being charged with sensitive reagents and the anti-resolve characteristics of sensitive reagents charged in the materials were very well. By combining with special sensitive reagents, the porous glass fibers could be made into a series of fiber optic chemical sensors with different characteristics.
基金National Natural Science Foundation of China (51772277)the National Key R&D Program of China (2017YFB0304000)
文摘In order to improve the properties of alumina-carbon refractories,specimens were prepared using white fused corundum,zirconia-mullite and flake graphite as the raw materials,phenolic resin as the binder,adding different mass fractions(1.5%,2.0%,and 2.5%,respectively)of glass dust,cold isostatic pressing by 120 MPa,drying and firing at 900℃for 3 h.Effects of the glass dust addition on the apparent porosity,bulk density,cold modulus of rupture,hot modulus of rupture and thermal shock resistance were studied.The results show that the cold modulus of rupture of the specimens is improved significantly as the results of glass dust accelerating sintering.However,the hot modulus of rupture decreases.As the glass phase buffers the strain produced by thermal shock,the thermal shock resistance of alumina-carbon specimens is improved,especially for low carbon alumina-carbon materials.
