The crystallization behavior and kinetics of CaO-MgO-Al2O3 SiO2（CMAS） glass with the Fe2O3 content ranging from zero to 5%were investigated by differential scanning calorimetry（DSC）.The structure and phase analyse...The crystallization behavior and kinetics of CaO-MgO-Al2O3 SiO2（CMAS） glass with the Fe2O3 content ranging from zero to 5%were investigated by differential scanning calorimetry（DSC）.The structure and phase analyses were made by Fourier transform infrared spectroscopy（FT-IR） and X-ray diffraction（XRD）.The experiment results show that the endothermic peak temperature about 760℃ is associated with transition and the exothermic peak temperature about 1000℃ is associated with crystallization.The crystallization peak temperature decreases with increasing the Fe203 content.The crystallization mechanism is changed from two-dimensional crystallization to one-dimensional growth,and the intensity of diopside peaks becomes stronger gradually.There is a saltation for the crystallization temperature with the addition of 0.5%Fe2O3 due to the decomposition of Fe2O3.Si-O-Si,O-Si-O and T-O-T（T=Si,Fe,Al） linkages are observed in Fe2O3-CaO-MgO-Al2O3-SiO2 glass.展开更多
CaO-B203-SiO2 （CBS） glass powders are prepared by conventional glass melting method at different melting temperatures whose properties and microstructures are characterized by X-ray diffraction （XRD） and scanning ...CaO-B203-SiO2 （CBS） glass powders are prepared by conventional glass melting method at different melting temperatures whose properties and microstructures are characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. It is found that there are SiO2 and some unknown phases in CBS glass melting liquid from 1 300 ℃ to 1 500 ℃ and the amount of these phases decreases with the increase of the melting temperature. The CBS glass melted at 1 450 ℃ could be sintered from 830 ℃ to 930 ℃ and the bulk densities of the samples are all higher than 2.4 g/cm^3. From the points of the properties and energy conservation, the melting temperature of 1 450 ℃ is the optimal melting temperature. The glass ceramic sintered at 850 ℃ exhibits better dielectric properties： er=6.33, tan6=2.2×10^-3 at 10 GHz, and the major phases of the samples are CaSiO3, CaB2O4 and SiO2.展开更多
In order to investigate the effect of the La2O3 on the phase separation and crystallization of ZnO-B2O3-SiO2 glass, after the occurence of the phase separation and crystallization of glasses by heat treatment, the mic...In order to investigate the effect of the La2O3 on the phase separation and crystallization of ZnO-B2O3-SiO2 glass, after the occurence of the phase separation and crystallization of glasses by heat treatment, the microstructure morphology and distribution of elements in different sample areas were characterized by the scanning electron microscopy(SEM) and energy dispersive spectroscopy(EDS);the non-isothermal crystallization kinetics of the glass samples was studied by using a differential scanning calorimeter(DSC) and the precipitated crystals of crystallized glass were determined by the X-ray diffraction(XRD). The results suggest that the phase separation and crystallization of 60ZnO-30 B2O3-10SiO2 glass occur at glass surface, and the incorporation of small amount(<4 mol%) of La2O3 significantly inhibits the glass phase separation and consequently improves the thermal stability of glass.Doping of La2O3 accelerates the glass crystallization at the elevated temperature(660 ℃), making the depth of crystal layer thicker and diffraction intensity in XRD patterns stronger. However, due to the precipitation of several crystals that occur simultaneously when La2O3 doping amount is 4 mol%, crystallization of the 60ZnO-30B2O3-10SiO2 glass is obviously depressed, the crystallization activation energy Ec and the relative crystallinity Xc of the glass reach the maximum and the minimum values, respectively.Although transition from one-dimensional growth of crystals to two-dimensional growth of crystals results from La2O3 addition, the one-dimensional growth of crystals remains dominant in crystallization process. This work can provide some useful information for preparing glass ceramics with nano-crystals precipitated in the glass surface.展开更多
The Eu-doped SiO2-B2O3-NaF glass was prepared by sol-gel process, using tetraethoxy Silicane, boric acid and sodium fluoride as starting materials, 0.10 mol·L-1 EuCl3 solution as the dopant. The luminescent prope...The Eu-doped SiO2-B2O3-NaF glass was prepared by sol-gel process, using tetraethoxy Silicane, boric acid and sodium fluoride as starting materials, 0.10 mol·L-1 EuCl3 solution as the dopant. The luminescent properties of Eu3+ doped SiO2-B2O3-NaF phosphors were investigated. The phosphors showed prominent luminescence in pink, the strong emission of Eu3+ comes from electronic transition of 5D0-7F1(591 nm)and 5D0-7F2(615 nm),which derived from two transition modes of magnetic-dipole and electric-dipole .The peak intensity of 591nm in SiO2-B2O3-NaF matrix is much stronger than it in the other matrixes, it means that SiO2-B2O3-NaF has sensitization on the transition of 5D0-7F1 (Eu3+). If there are broad bonds in the range of 275~380 nm in the excitation spectrum of Eu3+ -doped SiO2-B2O3-NaF glass, the emission peak intensity should be intensified. It is because the electron migration CT band of O2--Eu3+. For all Eu3+ concentrations used, the investigation found that when the mass of fraction got to 29.19×10-3, the luminescence intensity reached the summit. And there is a phenomenon of concentration quenching. Investigation with the same concentration of Eu3+ at different annealed temperature, we found that the sample annealed at 400 ℃, the luminescence intensity achieved its maximum value, and Eu3+ in this matrix had a phenomenon of temperature quenching. The structural characterization of these luminescent materials was carried by used XRD and TEM. The result showed that the phosphor was in amorphous phase.展开更多
B_2O_3-SiO_2-ZnO-BaO-Al_2O_3 glass with different Al_2O_3 contents（1mol%, 3mol%, 5mol%, and 7mol%） was prepared, and it was intended to be used as lead-free and low-melting glass sealants for solid oxide fuel cells....B_2O_3-SiO_2-ZnO-BaO-Al_2O_3 glass with different Al_2O_3 contents（1mol%, 3mol%, 5mol%, and 7mol%） was prepared, and it was intended to be used as lead-free and low-melting glass sealants for solid oxide fuel cells. The effects of Al_2O_3 content on the structures, thermal properties, and sintering behaviors of the B_2O_3-SiO_2-ZnO-BaO-Al_2O_3 glass were investigated in detail. The Al_2O_3 content largely influenced the structures and thermal properties of the glass. When the Al_2O_3 content 5mol%, the transition temperature of the glass decreased with the Al_2O_3 content, while the crystallization temperature increased with the Al_2O_3 content. However, higher Al_2O_3 content degraded the stability of the glass. The B_2O_3-SiO_2-ZnO-BaO-Al_2O_3 glass with 5 mol% Al_2O_3 content exhibits the optimal sintering densification characteristics and can be used as glass sealants for solid oxide fuel cells.展开更多
基金Projects(51264023,51364020,U1202271)supported by the National Natural Science Foundation of ChinaProject(IRT1250)supported by the Program for Innovative Research Team in University of Ministry of Education of ChinaProject(2014HA003)supported by the Science and Technology Leading Talent of Yunnan Province,China
文摘The crystallization behavior and kinetics of CaO-MgO-Al2O3 SiO2（CMAS） glass with the Fe2O3 content ranging from zero to 5%were investigated by differential scanning calorimetry（DSC）.The structure and phase analyses were made by Fourier transform infrared spectroscopy（FT-IR） and X-ray diffraction（XRD）.The experiment results show that the endothermic peak temperature about 760℃ is associated with transition and the exothermic peak temperature about 1000℃ is associated with crystallization.The crystallization peak temperature decreases with increasing the Fe203 content.The crystallization mechanism is changed from two-dimensional crystallization to one-dimensional growth,and the intensity of diopside peaks becomes stronger gradually.There is a saltation for the crystallization temperature with the addition of 0.5%Fe2O3 due to the decomposition of Fe2O3.Si-O-Si,O-Si-O and T-O-T（T=Si,Fe,Al） linkages are observed in Fe2O3-CaO-MgO-Al2O3-SiO2 glass.
基金Project(2007AA03Z0455) supported by the National High Technology Research and Development Program of ChinaProject(BE2010194) supported by Science&Technology Pillar Program of Jiangsu Province, China+1 种基金Project(KF201103) supported by the State Key Laboratory of New Ceramic and Fine Processing, Tsinghua University, ChinaProject supported by the Priority Academic Development of Jiangsu Higher Education Institutions, China
文摘CaO-B203-SiO2 （CBS） glass powders are prepared by conventional glass melting method at different melting temperatures whose properties and microstructures are characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. It is found that there are SiO2 and some unknown phases in CBS glass melting liquid from 1 300 ℃ to 1 500 ℃ and the amount of these phases decreases with the increase of the melting temperature. The CBS glass melted at 1 450 ℃ could be sintered from 830 ℃ to 930 ℃ and the bulk densities of the samples are all higher than 2.4 g/cm^3. From the points of the properties and energy conservation, the melting temperature of 1 450 ℃ is the optimal melting temperature. The glass ceramic sintered at 850 ℃ exhibits better dielectric properties： er=6.33, tan6=2.2×10^-3 at 10 GHz, and the major phases of the samples are CaSiO3, CaB2O4 and SiO2.
基金Project supported by National Natural Science Foundation of China(51662033,51362019)Natural Science Foundation of the Inner Mongolia Autonomous Region(2016JQ05)
文摘In order to investigate the effect of the La2O3 on the phase separation and crystallization of ZnO-B2O3-SiO2 glass, after the occurence of the phase separation and crystallization of glasses by heat treatment, the microstructure morphology and distribution of elements in different sample areas were characterized by the scanning electron microscopy(SEM) and energy dispersive spectroscopy(EDS);the non-isothermal crystallization kinetics of the glass samples was studied by using a differential scanning calorimeter(DSC) and the precipitated crystals of crystallized glass were determined by the X-ray diffraction(XRD). The results suggest that the phase separation and crystallization of 60ZnO-30 B2O3-10SiO2 glass occur at glass surface, and the incorporation of small amount(<4 mol%) of La2O3 significantly inhibits the glass phase separation and consequently improves the thermal stability of glass.Doping of La2O3 accelerates the glass crystallization at the elevated temperature(660 ℃), making the depth of crystal layer thicker and diffraction intensity in XRD patterns stronger. However, due to the precipitation of several crystals that occur simultaneously when La2O3 doping amount is 4 mol%, crystallization of the 60ZnO-30B2O3-10SiO2 glass is obviously depressed, the crystallization activation energy Ec and the relative crystallinity Xc of the glass reach the maximum and the minimum values, respectively.Although transition from one-dimensional growth of crystals to two-dimensional growth of crystals results from La2O3 addition, the one-dimensional growth of crystals remains dominant in crystallization process. This work can provide some useful information for preparing glass ceramics with nano-crystals precipitated in the glass surface.
文摘The Eu-doped SiO2-B2O3-NaF glass was prepared by sol-gel process, using tetraethoxy Silicane, boric acid and sodium fluoride as starting materials, 0.10 mol·L-1 EuCl3 solution as the dopant. The luminescent properties of Eu3+ doped SiO2-B2O3-NaF phosphors were investigated. The phosphors showed prominent luminescence in pink, the strong emission of Eu3+ comes from electronic transition of 5D0-7F1(591 nm)and 5D0-7F2(615 nm),which derived from two transition modes of magnetic-dipole and electric-dipole .The peak intensity of 591nm in SiO2-B2O3-NaF matrix is much stronger than it in the other matrixes, it means that SiO2-B2O3-NaF has sensitization on the transition of 5D0-7F1 (Eu3+). If there are broad bonds in the range of 275~380 nm in the excitation spectrum of Eu3+ -doped SiO2-B2O3-NaF glass, the emission peak intensity should be intensified. It is because the electron migration CT band of O2--Eu3+. For all Eu3+ concentrations used, the investigation found that when the mass of fraction got to 29.19×10-3, the luminescence intensity reached the summit. And there is a phenomenon of concentration quenching. Investigation with the same concentration of Eu3+ at different annealed temperature, we found that the sample annealed at 400 ℃, the luminescence intensity achieved its maximum value, and Eu3+ in this matrix had a phenomenon of temperature quenching. The structural characterization of these luminescent materials was carried by used XRD and TEM. The result showed that the phosphor was in amorphous phase.
基金Funded by the Jiangxi Provincial Department of Education(KJLD13008)the National Natural Science Foundation of China(number 51362020)the Research Fund for the Doctoral Program of Higher Education(20123601110006)
文摘B_2O_3-SiO_2-ZnO-BaO-Al_2O_3 glass with different Al_2O_3 contents（1mol%, 3mol%, 5mol%, and 7mol%） was prepared, and it was intended to be used as lead-free and low-melting glass sealants for solid oxide fuel cells. The effects of Al_2O_3 content on the structures, thermal properties, and sintering behaviors of the B_2O_3-SiO_2-ZnO-BaO-Al_2O_3 glass were investigated in detail. The Al_2O_3 content largely influenced the structures and thermal properties of the glass. When the Al_2O_3 content 5mol%, the transition temperature of the glass decreased with the Al_2O_3 content, while the crystallization temperature increased with the Al_2O_3 content. However, higher Al_2O_3 content degraded the stability of the glass. The B_2O_3-SiO_2-ZnO-BaO-Al_2O_3 glass with 5 mol% Al_2O_3 content exhibits the optimal sintering densification characteristics and can be used as glass sealants for solid oxide fuel cells.
