The effect of alumina content and heat treatment temperature and time, on microstructure and Er3＋ （0.5 mol.%） emission of oxyfluoride glass-ceramics were investigated in this research. Two values of 1.8 （SA1.8Er0....The effect of alumina content and heat treatment temperature and time, on microstructure and Er3＋ （0.5 mol.%） emission of oxyfluoride glass-ceramics were investigated in this research. Two values of 1.8 （SA1.8Er0.5） and 2.18 （SA2.18Er0.5） were selected in this research for SiO2/Al2O3 ratio. According to DTA results, precursor glasses were heat treated at 630, 660 and 690 ℃ for 4 h and some glasses were also heat treated at 630 ℃ for 48 and 72 h. The results indicated that alumina content had significant effect on phase separation and viscosity of the glasses. Therefore the size, size distribution, and volume concentration of nano CaF2 crystals which precipitated during the heat treatment depended on alumina content of the glass. Due to the much smaller size of the precipitated CaF2 crystals in the glasses of low alumina content, these samples maintained excellent transparency and had narrower crystal size distribution than the high alumina glasses. The crystal size was increased markedly with the temperature increasing from 630 to 690 ℃. On the other hand a slight increase was observed in the crystal size by raising the heat treatment time in both glasses. Results indicated that in low alumina content glass （SA2.18Er0.5） the size of CaF2 nanocrystals was controlled in one order of magnitude. The increase of heat treatment time and temperature led to the incorporation of Er3＋ ions into CaF2 crystalline phase, increasing significantly the upconversion intensity. After heat treatment at 690 ℃for 4 h, atomic force microscope （AFM） revealed the development of small crystals with an average size of 80 and 30 nm in SA1.8Er0.5 and SA2.18Er0.5 samples, respectively.展开更多
In current research,Li_(2)O-Al_(2)O_(3)-SiO_(2)glass-ceramics were prepared by conventional meltquenching and subsequent heat treatment method.The effect of Al_(2)O_(3)content on microstructures,thermal properties,cry...In current research,Li_(2)O-Al_(2)O_(3)-SiO_(2)glass-ceramics were prepared by conventional meltquenching and subsequent heat treatment method.The effect of Al_(2)O_(3)content on microstructures,thermal properties,crystallization behaviours and mechanical properties were investigated.FTIR,Raman spectroscopy and nuclear magnetic resonance spectroscopy microstructure analysis showed that the silico-oxygen network was damaged,while the increase of[AlO_(4)]content repaired the glass network,and finally made the glass network have better connectivity,with the decrease of SiO_(2).The thermal analysis confirmed the increasing glass transition and crystallization temperatures from growing Al_(2)O_(3)content.In addition,different crystal phases can be precipitated in the glass matrix,such as LiAlSi_(4)O_(10),Li_(2)Si_(2)O_(5) in glass with low Al_(2)O_(3)content,the combination of Li_xAl_xSi_(1-x)O_(2),LiAlSi_(3)O_(8),Li_(2)SiO_(3)in glass with intermediate Al_(2)O_(3)content,and the combination of LiAlSi_(2)O_(6),SiO_(2)in glass with high Al_(2)O_(3)content.The hardness of as-prepared glass gradually increases with the increase of the Al_(2)O_(3)content.The Vickers hardness of the glass-ceramics is highly dependent on the Al_(2)O_(3)content in the glass and the heat treatment temperatures,reaching a maximum of 10.11 GPa.Scanning electron microscope images show that the crystals change from spherical to massive and finally to sheet.The change of glass structure,crystal phase and morphology is the main reason for the different mechanical properties.展开更多
Waste glass fibers were used as the main raw materials to prepare foamed glass-ceramics with 0-14 wt%H_(3)BO_(3)as a flux agent.The effects of H_(3)BO_(3)on the crystallization process,foaming behavior,and physical pr...Waste glass fibers were used as the main raw materials to prepare foamed glass-ceramics with 0-14 wt%H_(3)BO_(3)as a flux agent.The effects of H_(3)BO_(3)on the crystallization process,foaming behavior,and physical properties of CaO-MgO-Al_(2)O_(3)-SiO_(2)foamed glass-ceramics were investigated.The results showed that the main crystalline phase of the foamed glass-ceramics was anorthite with diopside as a minor crystalline phase,which exhibited a typical surface crystallization process.The addition of H_(3)BO_(3)modified the surface of glass powders and inhibited crystal precipitation obviously.The low melting point of H_(3)BO_(3)and the decrease of crystallinity jointly promoted the growth of pores,resulting in a reduction of bulk density and an increase in porosity.The compressive strength and thermal conductivity of the samples were linearly related to the bulk density.In particular,the sample added with 10 wt%H_(3)BO_(3)exhibited excellent properties,possessing a low coefficient of thermal conductivity 0.081 W/(m·K)and relatively high compressive strength 3.36 MPa.展开更多
The substitution of TiO_(2)for SiO_(2)in Y_(2)O_(3)-Li_(2)O-Al_(2)O_(3)-SiO_(2)(YLAS)glass-ceramics significantly altered their crystallization behavior and properties.Introducing TiO_(2)reduced the glass transition t...The substitution of TiO_(2)for SiO_(2)in Y_(2)O_(3)-Li_(2)O-Al_(2)O_(3)-SiO_(2)(YLAS)glass-ceramics significantly altered their crystallization behavior and properties.Introducing TiO_(2)reduced the glass transition temperature while increasing the crystallization peak temperature and lowering activation energy,which facilitated crystallization.The crystal growth shifted from three-dimensional to two-dimensional,and the primary phases transitioned from Al_(9.83)Zr_(0.17)and Y_(2)Si_(2)O_(7)to Y_(4.67)(SiO_(4))_(3)O,though crystal morphology remained unchanged.Grain size increased with higher crystallization temperatures.Mechanically,Vickers hardness slightly decreased(from 796 to 784 Hv),while bending strength improved(from 141 to 146 MPa),suggesting that TiO_(2)enhanced toughness without compromising structural integrity.The strength of the glass can be further improved through two-step ion exchange,but excessive crystallization can lead to cracks on the glass surface due to excessive surface compressive stress,resulting in a decrease in bending strength.These findings provide critical insights for optimizing YLAS glass-ceramics for advanced applications.展开更多
Erbium doped silicate, germanate, and tellurium-germanate oxyfluoride glasses were prepared in a bulk form. Through appropriate heat treatment of the as-prepared glasses, transparent glass-ceramics （TGCs） were obtai...Erbium doped silicate, germanate, and tellurium-germanate oxyfluoride glasses were prepared in a bulk form. Through appropriate heat treatment of the as-prepared glasses, transparent glass-ceramics （TGCs） were obtained with the formation of β-PbF2：Er^3＋ nanocrystals in the glass matrix were confirmed by X-ray diffraction.Well-defined diffraction peaks were observed in the samples after heat-treatment. The average crystal diameter of these precipitated crystals from full-width at half-maximum （FWHM） of the diffraction peak was estimated to be between 8 and 13 nm. Optical absorption, photoluminescence, and upconversion luminescence were measured on as-prepared glass and glass-ceramics. Luminescence spectra in the TGC samples revealed well-resolved, sharp stark-splitting peaks, which indicates that a majority of Er^3＋ ions has been incorporated into the crystalline phase of the nanocrystals. The intensity of the visible and near infrared luminescence mostly increases in TSG compared to that in the as-prepared glass. In 1.53 μm absorption and emission bands, the maximum absorption peak is blue-shifted from 1531 to 1507 nm, whereas the maximum emission peak is redshifted from 1535 to 1543 nm in TGC, as compared with that in glass. The bandwidth at half-maximum （BWHM） of the emission band is significantly broader in TGC than in glass, which is beneficial to the erbium-doped fiber amplifier （EDFA）. Upconversion luminescence was measured using 800 nm near-infrared light excitation. Drastically increased upconversion 1 was observed from the TGC as compared to that from their corresponding as-prepared glasses. In addition to a strong green emission centered at 545 nm because of ^4S3/2→^4I15/2 transition and a weaker red emission centered at 662 nm because of ^4F9/2→^4I15/2 transition, generally seen from the Er^3＋ doped glasses, two violet emissions centered at 410 nm because of ^2H9/2→^4I15/2 transition and centered at 379 nm because of ^4G11/2→^4I15/2 transition were also observed from the was attributed to the decreased effective phonon energy and the increased energy transfer between the excited ions when Er^3＋ ions were incorporated into the precipitated β-PbF2 nanocrystals. The results indicated two attractive spectroscopic properties of the Er^3＋ doped TGC samples, compared to glass samples, namely a reduced multiphonon decay rate and a reduced inhomogeneous broadening. In addition, these oxyfluoride TGC materials were robust,easy and flexibile to process, and possible to be fabricated in the fiber form for device applications.展开更多
Abstract In recent years, our research group has developed and studied new rare-earth doped materials for the promising technology of solid-state laser cooling, which is based on anti-stokes fluorescence. To the best ...Abstract In recent years, our research group has developed and studied new rare-earth doped materials for the promising technology of solid-state laser cooling, which is based on anti-stokes fluorescence. To the best of our knowledge, our group is the only one in Canada leading the research into the properties of nanoparticles, glasses and glass-ceramics for optical refrigeration appli- cations. In the present work, optical properties of 50GeO2- 30PbF2-18PbO-2YbF3 glass-ceramics for laser cooling are presented and discussed as a function of crystallization temperature. Spectroscopic results show that samples have near infrared photoluminescence emission due to the 2F5/2 - 2F7/2 Yb3＋ transition, centered at -1016 nm with an excitation wavelength of 920 nm or 1011 nm, and the highest photoluminescence emission efficiency occurs for heat-treatment for 5 h at 350℃. The internal photolumi- nescence quantum yield varies between 99% and 80%, depending on the temperature of heat-treatment, being the most efficient under 1011 nm excitation. The 2F5/2 lifetime increases from 1.472 to 1.970 ms for heat treatments at 330℃ to 350℃, respectively, due to energy trapping and the low phonon energy of the nanocrystals. The sample temperature dependence was measured with a fiber Bragg grating sensor, as a function of input pump laser wavelength and processing temperature. These measure- ments show that the heating process approaches near zero for an excitation wavelength between 1020 and 1030 nm, which is an indication that phonons are removed effectivelly from the glass-ceramic materials, and they can be used for optical laser cooling applications. On theother hand, the temperature increase as a function of input laser power into samples remains constant between 920 and 980 nm wavelength excitation, a temperature variation of 36 K/W （temperature of 58℃/W） was attained under excitation at 950 nm, showing a possible use for biomedical applications to be explored.展开更多
Silicate glass-ceramics were prepared by adding 40 wt%granite wastes.The effects of CaO/MgO(C/M)molar ratio on microstructure and mechanical properties of glass-ceramics were investigated.With C/M ratio increasing,the...Silicate glass-ceramics were prepared by adding 40 wt%granite wastes.The effects of CaO/MgO(C/M)molar ratio on microstructure and mechanical properties of glass-ceramics were investigated.With C/M ratio increasing,the crystallization behavior changed from bulk crystallization to surface crystallization with heat treatment at 800℃.However,bulk crystallization occurred in all samples when crystallized at both 850 and 900℃.The content of forsterite and tainiolite initially increased and then decreased,while diopside and kalsilite increased when heated at 850℃.For 900℃,the increase of C/M ratio promoted the precipitation of diopside rather than forsterite and tainiolite,and interlocked plate crystals abundantly appeared with C/M ratio≥0.14.The values of Vickers hardness for samples crystallized at 850 and 900℃increased initially followed by a decrease,while the values of fracture toughness showed the opposite trend.The glass-ceramic with C/M ratio 0.065 heated at 900℃showed relatively high Vickers hardness((5.7±0.14)GPa)and excellent fracture toughness((3.55±0.14)MPa·m^(1/2)).展开更多
High-entropy(HE)design provides ample opportunities for accessing catalysts with unique physiochemical properties for advanced energy and environmental applications.Although a variety of multi-cationic high-entropy ma...High-entropy(HE)design provides ample opportunities for accessing catalysts with unique physiochemical properties for advanced energy and environmental applications.Although a variety of multi-cationic high-entropy materials(HEMs)have been identified,HEMs consisted of multiple cationic and anionic elements are still limited.Herein,we present the design and synthesis of a series of rutile-structured high-entropy oxy fluorides(HEOFs),including[RuO_(2)]_(x)[MgMnZnCoF_(2)]_(y),[MnO_(2)]_(x)[MgMnZnCoF_(2)]_(y),[MoO_(2)]_(x)[MgMnZnCoF_(2)]_(y),[SnO_(2)]_(x)[MgMnZnCoF_(2)]_(y)and[TiO_(2)]_(x)[MgMnZnCoF_(2)]_(y)(x:y=3:1,2:1,1:1).All the HEOFs are obtained through mechanochemical alloying rutile-structured oxide and fluoride precursors and the HEOFs inherit the crystal structures of the skeleton oxides.Moreover,the HEOFs exhibit enhanced electrocatalytic oxygen evolution reaction(OER)activity than the corresponding oneelement precursors.Typically,the best-performed HEOF[RuO_(2)]_(3)[MgMnZnCoF_(2)]_(1)catalyst requires an overpotential of 240 mV to achieve a current density of 10 mA cm^(-2),which is lower than RuO_(2)(291 mV),More impressively,the specific mass activity of[RuO_(2)]_(3)[MgMnZnCoF_(2)]_(1)is 537.1 A g_(Ru)^(-1)at1.55 V(vs RHE),which is ca.7.6 times that of RuO_(2)(70.5 A g_(Ru)^(-1)).The enhanced electrocata lytic OER performance obtained on[RuO_(2)]_(3)[MgMnZnCoF_(2)]_(1)is ascribed to the contribution of the different cationic and anionic elements that modulates the electronic structures of the pristine RuO_(2),which facilitates efficient OER kinetics.This work demonstrates the efficacy of high-entropy design towards approaching excellent catalysts for enhanced electrocatalysis.展开更多
Iron phosphate based glass-ceramics with deliberately added Ce as an active nuclide simulant were prepared by microwave sintering.The sintering characteristics,including phases and structural evolution,and chemical du...Iron phosphate based glass-ceramics with deliberately added Ce as an active nuclide simulant were prepared by microwave sintering.The sintering characteristics,including phases and structural evolution,and chemical durability were investigated.XRD showed that NaZr_(2)(PO_(4))_(3) and FePO_(4) became the main crystalline phases of glass-ceramics with increasing sintering temperature.SEM revealed the glass-ceramics compactness increased first and then decreased as sintering temperature increased.Raman spectrum showed that,as sintering temperature increased,the network structure of glass-ceramics changed from mainly containing orthophosphate and pyrophosphate to a single orthophosphate.After immersion for 28 days,LR_(Na),LR_(Zr) and LR_(Ce) of the glass-ceramics prepared at 1000℃ were as low as 3.64×10^(-5),0.25×10^(-9) and 5.70×10^(-9)g/m^(2)/d respectively.The results indicate that iron phosphate based glass-ceramics can be prepared by rapid microwave sintering of glass powders and there is a potential of employing such microwave sintering technique in processing of glass-ceramics nuclear waste form.展开更多
Glass-ceramic materials of strontium barium niobate system were prepared through a melt-quenching method. The effects of crystallization temperature on the mierostructure, dielectric property, breakdown strength and e...Glass-ceramic materials of strontium barium niobate system were prepared through a melt-quenching method. The effects of crystallization temperature on the mierostructure, dielectric property, breakdown strength and energy storage density of barium strontium niobate glass-ceramics were studied. The crystallization mechanism of the glass-ceramics was discussed and should be one-dimensional interfacial growth. The results indicate that the breakdown strength remarkably increases with the increase of crystallization temperature. The glass-ceramic heat treated at 900 ℃ was found to possess optimal properties with breakdown strength of 1300 kV/cm and energy storage density of 2.8 J/cm3, which is promising dielectric materials for high energy storage density dielectrics.展开更多
Rare earth ions doped oxyfluoride glass with composition of 28SiO2·22AlO1.5·40PbF2·10PbO·（4.8-x） GdFy0.1NdF3.xYbF3·0.1TmF3 （x=-0, 0.1, 0.2, 0.5, 1, 2, 3, 4 and 4.8） in molar ratio was deve...Rare earth ions doped oxyfluoride glass with composition of 28SiO2·22AlO1.5·40PbF2·10PbO·（4.8-x） GdFy0.1NdF3.xYbF3·0.1TmF3 （x=-0, 0.1, 0.2, 0.5, 1, 2, 3, 4 and 4.8） in molar ratio was developed. When the oxyfluoride glasses were heat-treated at the first crystallization temperature, the glasses gave transparent glass-ceramics in which rare earth containing fluorite-type nanocrystals of about 17.2 nm in diameter uniformly precipitated in the glass matrix. Compared with the glasses before heat treatment, the glass-ceramics exhibited very strong blue up-conversion luminescence under 800 nm light excitation. Rare earth containing nanocrystals were also space selectively precipitated upon laser irradiation in an oxyfluoride glass, the size of precipitated nanocrystals could be controlled by laser power and scan speed. The intensity of the blue up-conversion luminescence was strongly dependent on the precipitation of β-PbF2 nanocrystal and the YbF3 concentration. The reasons for the highly efficient Tm^3＋ up-conversion luminescence after laser irradiation were discussed.展开更多
Oxyfluoride borosilicate glass with the molar composition of 60SiO2-15B2O3- 15Na2O-8CaF2-2NaF-0.25Eu2O3 was synthesized lay a traditional glass melting method. Glass ceramics containing CaF2 nanocrystals were prepared...Oxyfluoride borosilicate glass with the molar composition of 60SiO2-15B2O3- 15Na2O-8CaF2-2NaF-0.25Eu2O3 was synthesized lay a traditional glass melting method. Glass ceramics containing CaF2 nanocrystals were prepared by heat treating the glass samples at a temperature in the range of 6204580 ℃. The results of X-ray diffraction （XRD） indicated that the average crystallite size and the lattice constant of CaF2 nanocrystals increased with the heat treatment temperature increasing. The luminescence spectra showed that the emission intensity of Eu3＋ doped glass ceramics was stronger than that of the glass matrix, and increased with the heat treatment temperature increasing. The left edge of excitation band shifted to shorter wavelength in the glass ceramics. The local environments of Eu3＋ ions in the glass and glass ceramics were different.展开更多
Er3 +/Yb3 +-codoped oxyfluoride crystallite glass was prepared with melting technique. The compositions and the melting temperature and the annealing temperature of the rare earth-doped crystallite glass were studied ...Er3 +/Yb3 +-codoped oxyfluoride crystallite glass was prepared with melting technique. The compositions and the melting temperature and the annealing temperature of the rare earth-doped crystallite glass were studied in detail. The emission spectra of samples were measured with the Hitachi F-4500 fluorescent photometer pumped by 980 nm wavelength laser. The up-conversion luminescence mechanism was illuminated on the view of the photophysics. By measuring the relationship between luminescent intensity and pump power, it is confirmed that the emission peaks at 550 nm belong to two-photon process, while that at 665 nm belongs to three-photon process. Moreover, the distributions of crystalline were determined by SEM.展开更多
In order to investigate the influence of different heavy metal ions on the formation of the oxyfluoride glasses and glass ceramics, samples with different Pb F2/Cd F2 ratios have been prepared by the melting quenching...In order to investigate the influence of different heavy metal ions on the formation of the oxyfluoride glasses and glass ceramics, samples with different Pb F2/Cd F2 ratios have been prepared by the melting quenching and thermal treatment method. The different effects of Pb2 tand Cd2ton the glass network structure are investigated by FTIR and Raman spectra. During the formation of glass network structure, Pb2 tprefers to break the Sie Oe Si bond and subsequently bond to F for charge compensation, and Cd2 tprefers to break the SieO eA l bond and is surrounded by O2. Pb2 tand F gather together and form the fluoride nanocrystals,while Cd2 tremains in oxide matrix after thermal treatment. Introduction of proper Cd F2 is important to adjust and control the glass network structure and crystallization process in the fabrication of the transparent glass ceramics.展开更多
The transparent oxyfluoride glass ceramics containing Ba Gd F5 nanocrystals were prepared with a composition of 42 Si O2-12Na2O-16Al2O3-24 Ba F2-4Gd2O3-2Ce F3（mol.%） by thermal treatment technology. The typical DSC ...The transparent oxyfluoride glass ceramics containing Ba Gd F5 nanocrystals were prepared with a composition of 42 Si O2-12Na2O-16Al2O3-24 Ba F2-4Gd2O3-2Ce F3（mol.%） by thermal treatment technology. The typical DSC curve, X-ray diffraction（XRD） and transmission electron microscopy（TEM） patterns were measured. The transmission spectra and luminescent properties were investigated. The decay times of the Gd^3＋ ions at 312 nm excited with 275 nm for the Ce^3＋ ions doped glass and glass ceramics specimens and the energy transfer process between Gd^3＋ ions and Ce^3＋ ions were also studied. The XRD analysis and the TEM images confirmed the generation of the spherical Ba Gd F5 nanocrystals. Compared with the PG specimen, the intensity of the luminescence spectra of the glass ceramics specimens was apparently enhanced with the heat treatment temperature increasing, and a blue shift in the excitation spectra and the emission spectra of glass ceramics specimens was obviously observed. In the fluorescence decay curves of the Gd^3＋ ions, it could be obviously observed that the fluorescent intensity decays in the Ce^3＋ ions doped glass and glass ceramics specimens decreased rapidly with the increase of the heat treatment temperature. In addition, the energy transfer efficiency from Gd3＋ions to Ce^3＋ ions was also calculated.展开更多
Er3+/Yb3+-codoped transparent oxyfluoride borosilicate glass ceramics containing Ba2GdF7 nanocrystals were prepared and spectroscopic properties of rare earth ions were investigated. Fluoride nanocrystals Ba2GdF7 were...Er3+/Yb3+-codoped transparent oxyfluoride borosilicate glass ceramics containing Ba2GdF7 nanocrystals were prepared and spectroscopic properties of rare earth ions were investigated. Fluoride nanocrystals Ba2GdF7 were successfully precipitated in glass matrix, which was confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM) results. In comparison with the as-made precursor, significant enhancement of upconversion luminescence was observed in the Er3+/Yb3+ codoped oxyfluoride glass ceramics, which may be due to the variation of coordination environment around Er3+ and Yb3+ ions after crystallization. The transition mechanisms of the green and red upconversion luminescence were ascribed to a two-photon process, and that of the blue upconversion luminescence was a three-photon process.展开更多
Spectroscopic properties of Er3＋/Yb3＋-doped transparent oxyfluoride borosilicate glass ceramics containing YOF nanocrystals were systematically investigated. X-ray diffraction （XRD） confirmed the formation of YOF ...Spectroscopic properties of Er3＋/Yb3＋-doped transparent oxyfluoride borosilicate glass ceramics containing YOF nanocrystals were systematically investigated. X-ray diffraction （XRD） confirmed the formation of YOF nanocrystals in the glassy matrix. Based on the Judd-Ofelt theory, the intensity parameters Ωi （i=2, 4, 6）, spontaneous emission probability, radiative lifetime, radiative quantum efficiency and the effective emission bandwidth were investigated. The upconversion luminescence intensity of Er3＋ ions in the glass ceramics increased significantly with the increasing crystallization temperature. The transition mechanisms of the green and red upconversion luminescence were ascribed to a two-photon process, and the blue upconversion luminescence was a three-photon absorption process.展开更多
Municipal solid waste incineration(MSWI) fly ash is a by-product from municipal waste incineration.According to incomplete statistics, each year more than one million tons MSWI fly ash was produced in China. Owing to ...Municipal solid waste incineration(MSWI) fly ash is a by-product from municipal waste incineration.According to incomplete statistics, each year more than one million tons MSWI fly ash was produced in China. Owing to high heavy elements content, widely used disposal methods of landfill are not suitable for MSWI fly ash treatment. In this study, by using MSWI fly ash as raw materials, glassceramics was synthesized for the solidification of heavy metals and waste recycle. Process parameters, including composition, heat treatment temperature and time, were studied and optimized. Under optimizing conditions, the product has good properties of density of 3.42 g·cm^(-3) and Vickers hardness of 6.91 GPa. Moreover, the leaching concentration of heavy metal elements meets allowable values of toxicity characteristic leaching procedure(TCLP).This study offers an alternative for MSWI fly ash recycle.展开更多
To effectively reuse high-titanium blast furnace slag （TS）, foam glass-ceramics were successfully prepared by powder sintering at 1000℃. TS and waste glass were used as the main raw materials, aluminium nitride （...To effectively reuse high-titanium blast furnace slag （TS）, foam glass-ceramics were successfully prepared by powder sintering at 1000℃. TS and waste glass were used as the main raw materials, aluminium nitride （AIN） as the foaming agent, and borax as the fluxing agent. The influence of the amount of A1N added （lwt%-5wt%） on the crystalline phases, microstructure, and properties of the produced foam glass-ceramics was studied. The results showed that the main crystal phases were perovskite, diopside, and augite. With increasing A1N content, a transformation from diopside to augite occurred and the crystallinity of the pyroxene phases slightly decreased. Initially, the aver- age pore size and porosity of the foam glass-ceramics increased and subsequently decreased; similarly, their bulk density and compressive strength decreased and subsequently increased. The optimal properties were obtained when the foam glass-ceramics were prepared by adding 4wt% AIN.展开更多
The crystallization behavior of wollastonite glass-ceramics was investigated by means of X-ray diffraction （XRD） analysis and surface morphological observations, and the chemical compositions were evaluated by field...The crystallization behavior of wollastonite glass-ceramics was investigated by means of X-ray diffraction （XRD） analysis and surface morphological observations, and the chemical compositions were evaluated by field emission-scanning electron microscopy （FE-SEM） and energy dispersive X-ray spectroscopy （EDS）. Various heat treatment temperatures （850, 900, 950, 1000 and 1050 ℃） were used to obtain glass-ceramics of the ideal wollastonite crystal phase as well as optimum mechanical properties and chemical durability. From XRD, FE-SEM and EDS, the crystallization of acicular crystal phase in the matrix was achieved at heat treatment temperature of 1000 and 1050 ℃, and wollastonite （CaSiO3） was found in the acicular type main crystal phase in the glass-ceramics. Various properties, such as density, compressive strength, bending strength and chemical durability were also examined. The mechanical properties of glass-ceramics obtained at the heat treatment temperature of 1000 and 1050 ℃ were superior to those obtained at the heat treatment temperature of 850 ℃.展开更多
基金Project supported by ACIISI of Gobierno de Canarias (ID20100152)Ministerio de Economíay Competitividad of Spain(MINECO)within the National Program of Materials(MAT2010-21270-C04-02/-03/-04)+2 种基金the Consol-ider-Ingenio 2010 Program(MALTACSD2007-0045,www.malta-consolider.com)ACIISI(Gobierno de canarias)project ID20100152governments of Spainand India for the award of a project within the indo-Spanish Joint Programme of Cooperation in Science and Technology(PRI-PIBIN-2011-1153/DST-INT-Spain-P-38-11)
文摘The effect of alumina content and heat treatment temperature and time, on microstructure and Er3＋ （0.5 mol.%） emission of oxyfluoride glass-ceramics were investigated in this research. Two values of 1.8 （SA1.8Er0.5） and 2.18 （SA2.18Er0.5） were selected in this research for SiO2/Al2O3 ratio. According to DTA results, precursor glasses were heat treated at 630, 660 and 690 ℃ for 4 h and some glasses were also heat treated at 630 ℃ for 48 and 72 h. The results indicated that alumina content had significant effect on phase separation and viscosity of the glasses. Therefore the size, size distribution, and volume concentration of nano CaF2 crystals which precipitated during the heat treatment depended on alumina content of the glass. Due to the much smaller size of the precipitated CaF2 crystals in the glasses of low alumina content, these samples maintained excellent transparency and had narrower crystal size distribution than the high alumina glasses. The crystal size was increased markedly with the temperature increasing from 630 to 690 ℃. On the other hand a slight increase was observed in the crystal size by raising the heat treatment time in both glasses. Results indicated that in low alumina content glass （SA2.18Er0.5） the size of CaF2 nanocrystals was controlled in one order of magnitude. The increase of heat treatment time and temperature led to the incorporation of Er3＋ ions into CaF2 crystalline phase, increasing significantly the upconversion intensity. After heat treatment at 690 ℃for 4 h, atomic force microscope （AFM） revealed the development of small crystals with an average size of 80 and 30 nm in SA1.8Er0.5 and SA2.18Er0.5 samples, respectively.
基金Funded by the National Key Research Program(No.2024-1129-954-112)National Natural Science Foundation of China(No.52372033)Guangxi Science and Technology Major Program(No.AA24263054)。
文摘In current research,Li_(2)O-Al_(2)O_(3)-SiO_(2)glass-ceramics were prepared by conventional meltquenching and subsequent heat treatment method.The effect of Al_(2)O_(3)content on microstructures,thermal properties,crystallization behaviours and mechanical properties were investigated.FTIR,Raman spectroscopy and nuclear magnetic resonance spectroscopy microstructure analysis showed that the silico-oxygen network was damaged,while the increase of[AlO_(4)]content repaired the glass network,and finally made the glass network have better connectivity,with the decrease of SiO_(2).The thermal analysis confirmed the increasing glass transition and crystallization temperatures from growing Al_(2)O_(3)content.In addition,different crystal phases can be precipitated in the glass matrix,such as LiAlSi_(4)O_(10),Li_(2)Si_(2)O_(5) in glass with low Al_(2)O_(3)content,the combination of Li_xAl_xSi_(1-x)O_(2),LiAlSi_(3)O_(8),Li_(2)SiO_(3)in glass with intermediate Al_(2)O_(3)content,and the combination of LiAlSi_(2)O_(6),SiO_(2)in glass with high Al_(2)O_(3)content.The hardness of as-prepared glass gradually increases with the increase of the Al_(2)O_(3)content.The Vickers hardness of the glass-ceramics is highly dependent on the Al_(2)O_(3)content in the glass and the heat treatment temperatures,reaching a maximum of 10.11 GPa.Scanning electron microscope images show that the crystals change from spherical to massive and finally to sheet.The change of glass structure,crystal phase and morphology is the main reason for the different mechanical properties.
基金Funded by Shandong Provincial Youth Innovation Team Development Plan of Colleges and Universities(No.2022KJ100)National Natural Science Foundation of China(No.52172019)。
文摘Waste glass fibers were used as the main raw materials to prepare foamed glass-ceramics with 0-14 wt%H_(3)BO_(3)as a flux agent.The effects of H_(3)BO_(3)on the crystallization process,foaming behavior,and physical properties of CaO-MgO-Al_(2)O_(3)-SiO_(2)foamed glass-ceramics were investigated.The results showed that the main crystalline phase of the foamed glass-ceramics was anorthite with diopside as a minor crystalline phase,which exhibited a typical surface crystallization process.The addition of H_(3)BO_(3)modified the surface of glass powders and inhibited crystal precipitation obviously.The low melting point of H_(3)BO_(3)and the decrease of crystallinity jointly promoted the growth of pores,resulting in a reduction of bulk density and an increase in porosity.The compressive strength and thermal conductivity of the samples were linearly related to the bulk density.In particular,the sample added with 10 wt%H_(3)BO_(3)exhibited excellent properties,possessing a low coefficient of thermal conductivity 0.081 W/(m·K)and relatively high compressive strength 3.36 MPa.
基金Funded by the China Building Material Federation Projects(Nos.20221JBGS06-19 and 2023JBGS02-01)。
文摘The substitution of TiO_(2)for SiO_(2)in Y_(2)O_(3)-Li_(2)O-Al_(2)O_(3)-SiO_(2)(YLAS)glass-ceramics significantly altered their crystallization behavior and properties.Introducing TiO_(2)reduced the glass transition temperature while increasing the crystallization peak temperature and lowering activation energy,which facilitated crystallization.The crystal growth shifted from three-dimensional to two-dimensional,and the primary phases transitioned from Al_(9.83)Zr_(0.17)and Y_(2)Si_(2)O_(7)to Y_(4.67)(SiO_(4))_(3)O,though crystal morphology remained unchanged.Grain size increased with higher crystallization temperatures.Mechanically,Vickers hardness slightly decreased(from 796 to 784 Hv),while bending strength improved(from 141 to 146 MPa),suggesting that TiO_(2)enhanced toughness without compromising structural integrity.The strength of the glass can be further improved through two-step ion exchange,but excessive crystallization can lead to cracks on the glass surface due to excessive surface compressive stress,resulting in a decrease in bending strength.These findings provide critical insights for optimizing YLAS glass-ceramics for advanced applications.
基金Project supported by NSF/CREST HRD-0420516 , NSF-STC CLiPS Grant 0423914 ,and DOD/ARO Contracts : W911NF-05-1-0453 ,04-1-0040
文摘Erbium doped silicate, germanate, and tellurium-germanate oxyfluoride glasses were prepared in a bulk form. Through appropriate heat treatment of the as-prepared glasses, transparent glass-ceramics （TGCs） were obtained with the formation of β-PbF2：Er^3＋ nanocrystals in the glass matrix were confirmed by X-ray diffraction.Well-defined diffraction peaks were observed in the samples after heat-treatment. The average crystal diameter of these precipitated crystals from full-width at half-maximum （FWHM） of the diffraction peak was estimated to be between 8 and 13 nm. Optical absorption, photoluminescence, and upconversion luminescence were measured on as-prepared glass and glass-ceramics. Luminescence spectra in the TGC samples revealed well-resolved, sharp stark-splitting peaks, which indicates that a majority of Er^3＋ ions has been incorporated into the crystalline phase of the nanocrystals. The intensity of the visible and near infrared luminescence mostly increases in TSG compared to that in the as-prepared glass. In 1.53 μm absorption and emission bands, the maximum absorption peak is blue-shifted from 1531 to 1507 nm, whereas the maximum emission peak is redshifted from 1535 to 1543 nm in TGC, as compared with that in glass. The bandwidth at half-maximum （BWHM） of the emission band is significantly broader in TGC than in glass, which is beneficial to the erbium-doped fiber amplifier （EDFA）. Upconversion luminescence was measured using 800 nm near-infrared light excitation. Drastically increased upconversion 1 was observed from the TGC as compared to that from their corresponding as-prepared glasses. In addition to a strong green emission centered at 545 nm because of ^4S3/2→^4I15/2 transition and a weaker red emission centered at 662 nm because of ^4F9/2→^4I15/2 transition, generally seen from the Er^3＋ doped glasses, two violet emissions centered at 410 nm because of ^2H9/2→^4I15/2 transition and centered at 379 nm because of ^4G11/2→^4I15/2 transition were also observed from the was attributed to the decreased effective phonon energy and the increased energy transfer between the excited ions when Er^3＋ ions were incorporated into the precipitated β-PbF2 nanocrystals. The results indicated two attractive spectroscopic properties of the Er^3＋ doped TGC samples, compared to glass samples, namely a reduced multiphonon decay rate and a reduced inhomogeneous broadening. In addition, these oxyfluoride TGC materials were robust,easy and flexibile to process, and possible to be fabricated in the fiber form for device applications.
文摘Abstract In recent years, our research group has developed and studied new rare-earth doped materials for the promising technology of solid-state laser cooling, which is based on anti-stokes fluorescence. To the best of our knowledge, our group is the only one in Canada leading the research into the properties of nanoparticles, glasses and glass-ceramics for optical refrigeration appli- cations. In the present work, optical properties of 50GeO2- 30PbF2-18PbO-2YbF3 glass-ceramics for laser cooling are presented and discussed as a function of crystallization temperature. Spectroscopic results show that samples have near infrared photoluminescence emission due to the 2F5/2 - 2F7/2 Yb3＋ transition, centered at -1016 nm with an excitation wavelength of 920 nm or 1011 nm, and the highest photoluminescence emission efficiency occurs for heat-treatment for 5 h at 350℃. The internal photolumi- nescence quantum yield varies between 99% and 80%, depending on the temperature of heat-treatment, being the most efficient under 1011 nm excitation. The 2F5/2 lifetime increases from 1.472 to 1.970 ms for heat treatments at 330℃ to 350℃, respectively, due to energy trapping and the low phonon energy of the nanocrystals. The sample temperature dependence was measured with a fiber Bragg grating sensor, as a function of input pump laser wavelength and processing temperature. These measure- ments show that the heating process approaches near zero for an excitation wavelength between 1020 and 1030 nm, which is an indication that phonons are removed effectivelly from the glass-ceramic materials, and they can be used for optical laser cooling applications. On theother hand, the temperature increase as a function of input laser power into samples remains constant between 920 and 980 nm wavelength excitation, a temperature variation of 36 K/W （temperature of 58℃/W） was attained under excitation at 950 nm, showing a possible use for biomedical applications to be explored.
基金National Natural Science Foundation of China(Nos.52172019,51804131)Shandong Provincial Youth Innovation Team Development Plan of Colleges and Universities(No.2022KJ100)。
文摘Silicate glass-ceramics were prepared by adding 40 wt%granite wastes.The effects of CaO/MgO(C/M)molar ratio on microstructure and mechanical properties of glass-ceramics were investigated.With C/M ratio increasing,the crystallization behavior changed from bulk crystallization to surface crystallization with heat treatment at 800℃.However,bulk crystallization occurred in all samples when crystallized at both 850 and 900℃.The content of forsterite and tainiolite initially increased and then decreased,while diopside and kalsilite increased when heated at 850℃.For 900℃,the increase of C/M ratio promoted the precipitation of diopside rather than forsterite and tainiolite,and interlocked plate crystals abundantly appeared with C/M ratio≥0.14.The values of Vickers hardness for samples crystallized at 850 and 900℃increased initially followed by a decrease,while the values of fracture toughness showed the opposite trend.The glass-ceramic with C/M ratio 0.065 heated at 900℃showed relatively high Vickers hardness((5.7±0.14)GPa)and excellent fracture toughness((3.55±0.14)MPa·m^(1/2)).
基金financially supported by the National Natural Science Foundation of China(Grant No.22179015,21872142,22302026)the Liao Ning Revitalization Talents Program(XLYC1807196)+1 种基金the fund of the State Key Laboratory of Catalysis in DICP(N-22-06)the open fund of the State Key Laboratory of Molecular Reaction Dynamics in DICP,CAS(SKLMRD-K202414)。
文摘High-entropy(HE)design provides ample opportunities for accessing catalysts with unique physiochemical properties for advanced energy and environmental applications.Although a variety of multi-cationic high-entropy materials(HEMs)have been identified,HEMs consisted of multiple cationic and anionic elements are still limited.Herein,we present the design and synthesis of a series of rutile-structured high-entropy oxy fluorides(HEOFs),including[RuO_(2)]_(x)[MgMnZnCoF_(2)]_(y),[MnO_(2)]_(x)[MgMnZnCoF_(2)]_(y),[MoO_(2)]_(x)[MgMnZnCoF_(2)]_(y),[SnO_(2)]_(x)[MgMnZnCoF_(2)]_(y)and[TiO_(2)]_(x)[MgMnZnCoF_(2)]_(y)(x:y=3:1,2:1,1:1).All the HEOFs are obtained through mechanochemical alloying rutile-structured oxide and fluoride precursors and the HEOFs inherit the crystal structures of the skeleton oxides.Moreover,the HEOFs exhibit enhanced electrocatalytic oxygen evolution reaction(OER)activity than the corresponding oneelement precursors.Typically,the best-performed HEOF[RuO_(2)]_(3)[MgMnZnCoF_(2)]_(1)catalyst requires an overpotential of 240 mV to achieve a current density of 10 mA cm^(-2),which is lower than RuO_(2)(291 mV),More impressively,the specific mass activity of[RuO_(2)]_(3)[MgMnZnCoF_(2)]_(1)is 537.1 A g_(Ru)^(-1)at1.55 V(vs RHE),which is ca.7.6 times that of RuO_(2)(70.5 A g_(Ru)^(-1)).The enhanced electrocata lytic OER performance obtained on[RuO_(2)]_(3)[MgMnZnCoF_(2)]_(1)is ascribed to the contribution of the different cationic and anionic elements that modulates the electronic structures of the pristine RuO_(2),which facilitates efficient OER kinetics.This work demonstrates the efficacy of high-entropy design towards approaching excellent catalysts for enhanced electrocatalysis.
基金Funded by the Key Research and Development Projects of Anhui Province(No.2022a05020026)the Key Technologies R&D Program of CNBM(Nos.2021HX0809,2021HX1011)the Anhui Science and Technology Major Project(No.2021e03020009)。
文摘Iron phosphate based glass-ceramics with deliberately added Ce as an active nuclide simulant were prepared by microwave sintering.The sintering characteristics,including phases and structural evolution,and chemical durability were investigated.XRD showed that NaZr_(2)(PO_(4))_(3) and FePO_(4) became the main crystalline phases of glass-ceramics with increasing sintering temperature.SEM revealed the glass-ceramics compactness increased first and then decreased as sintering temperature increased.Raman spectrum showed that,as sintering temperature increased,the network structure of glass-ceramics changed from mainly containing orthophosphate and pyrophosphate to a single orthophosphate.After immersion for 28 days,LR_(Na),LR_(Zr) and LR_(Ce) of the glass-ceramics prepared at 1000℃ were as low as 3.64×10^(-5),0.25×10^(-9) and 5.70×10^(-9)g/m^(2)/d respectively.The results indicate that iron phosphate based glass-ceramics can be prepared by rapid microwave sintering of glass powders and there is a potential of employing such microwave sintering technique in processing of glass-ceramics nuclear waste form.
基金Project(51162002)supported by the National Natural Science Foundation of ChinaProject(2012-250)supported by the Science and Technology Project of Guangxi Returned Personnel,China
文摘Glass-ceramic materials of strontium barium niobate system were prepared through a melt-quenching method. The effects of crystallization temperature on the mierostructure, dielectric property, breakdown strength and energy storage density of barium strontium niobate glass-ceramics were studied. The crystallization mechanism of the glass-ceramics was discussed and should be one-dimensional interfacial growth. The results indicate that the breakdown strength remarkably increases with the increase of crystallization temperature. The glass-ceramic heat treated at 900 ℃ was found to possess optimal properties with breakdown strength of 1300 kV/cm and energy storage density of 2.8 J/cm3, which is promising dielectric materials for high energy storage density dielectrics.
基金supported by the National Natural Science Foundation of China (50572029) Natural Science Foundation Project of Yunnan Province (2007E036M)
文摘Rare earth ions doped oxyfluoride glass with composition of 28SiO2·22AlO1.5·40PbF2·10PbO·（4.8-x） GdFy0.1NdF3.xYbF3·0.1TmF3 （x=-0, 0.1, 0.2, 0.5, 1, 2, 3, 4 and 4.8） in molar ratio was developed. When the oxyfluoride glasses were heat-treated at the first crystallization temperature, the glasses gave transparent glass-ceramics in which rare earth containing fluorite-type nanocrystals of about 17.2 nm in diameter uniformly precipitated in the glass matrix. Compared with the glasses before heat treatment, the glass-ceramics exhibited very strong blue up-conversion luminescence under 800 nm light excitation. Rare earth containing nanocrystals were also space selectively precipitated upon laser irradiation in an oxyfluoride glass, the size of precipitated nanocrystals could be controlled by laser power and scan speed. The intensity of the blue up-conversion luminescence was strongly dependent on the precipitation of β-PbF2 nanocrystal and the YbF3 concentration. The reasons for the highly efficient Tm^3＋ up-conversion luminescence after laser irradiation were discussed.
基金Project supported by Educational Department of Liaoning (L2011063)
文摘Oxyfluoride borosilicate glass with the molar composition of 60SiO2-15B2O3- 15Na2O-8CaF2-2NaF-0.25Eu2O3 was synthesized lay a traditional glass melting method. Glass ceramics containing CaF2 nanocrystals were prepared by heat treating the glass samples at a temperature in the range of 6204580 ℃. The results of X-ray diffraction （XRD） indicated that the average crystallite size and the lattice constant of CaF2 nanocrystals increased with the heat treatment temperature increasing. The luminescence spectra showed that the emission intensity of Eu3＋ doped glass ceramics was stronger than that of the glass matrix, and increased with the heat treatment temperature increasing. The left edge of excitation band shifted to shorter wavelength in the glass ceramics. The local environments of Eu3＋ ions in the glass and glass ceramics were different.
文摘Er3 +/Yb3 +-codoped oxyfluoride crystallite glass was prepared with melting technique. The compositions and the melting temperature and the annealing temperature of the rare earth-doped crystallite glass were studied in detail. The emission spectra of samples were measured with the Hitachi F-4500 fluorescent photometer pumped by 980 nm wavelength laser. The up-conversion luminescence mechanism was illuminated on the view of the photophysics. By measuring the relationship between luminescent intensity and pump power, it is confirmed that the emission peaks at 550 nm belong to two-photon process, while that at 665 nm belongs to three-photon process. Moreover, the distributions of crystalline were determined by SEM.
基金supported by the National Science Fund for Talent Training in Basic Sciences (No. J1103208)
文摘In order to investigate the influence of different heavy metal ions on the formation of the oxyfluoride glasses and glass ceramics, samples with different Pb F2/Cd F2 ratios have been prepared by the melting quenching and thermal treatment method. The different effects of Pb2 tand Cd2ton the glass network structure are investigated by FTIR and Raman spectra. During the formation of glass network structure, Pb2 tprefers to break the Sie Oe Si bond and subsequently bond to F for charge compensation, and Cd2 tprefers to break the SieO eA l bond and is surrounded by O2. Pb2 tand F gather together and form the fluoride nanocrystals,while Cd2 tremains in oxide matrix after thermal treatment. Introduction of proper Cd F2 is important to adjust and control the glass network structure and crystallization process in the fabrication of the transparent glass ceramics.
基金supported by the National Natural Science Foundation of China(61275180,51472125)
文摘The transparent oxyfluoride glass ceramics containing Ba Gd F5 nanocrystals were prepared with a composition of 42 Si O2-12Na2O-16Al2O3-24 Ba F2-4Gd2O3-2Ce F3（mol.%） by thermal treatment technology. The typical DSC curve, X-ray diffraction（XRD） and transmission electron microscopy（TEM） patterns were measured. The transmission spectra and luminescent properties were investigated. The decay times of the Gd^3＋ ions at 312 nm excited with 275 nm for the Ce^3＋ ions doped glass and glass ceramics specimens and the energy transfer process between Gd^3＋ ions and Ce^3＋ ions were also studied. The XRD analysis and the TEM images confirmed the generation of the spherical Ba Gd F5 nanocrystals. Compared with the PG specimen, the intensity of the luminescence spectra of the glass ceramics specimens was apparently enhanced with the heat treatment temperature increasing, and a blue shift in the excitation spectra and the emission spectra of glass ceramics specimens was obviously observed. In the fluorescence decay curves of the Gd^3＋ ions, it could be obviously observed that the fluorescent intensity decays in the Ce^3＋ ions doped glass and glass ceramics specimens decreased rapidly with the increase of the heat treatment temperature. In addition, the energy transfer efficiency from Gd3＋ions to Ce^3＋ ions was also calculated.
基金Project supported by China Postdoctoral Science Foundation funded project (20080430216)National Natural Science Foundation of China (60508014)+1 种基金Program for New Century Excellent Talents in University (NCET-07-0786)Zhejiang Provincial Natural Science Foundation of China (Z4100030)
文摘Er3+/Yb3+-codoped transparent oxyfluoride borosilicate glass ceramics containing Ba2GdF7 nanocrystals were prepared and spectroscopic properties of rare earth ions were investigated. Fluoride nanocrystals Ba2GdF7 were successfully precipitated in glass matrix, which was confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM) results. In comparison with the as-made precursor, significant enhancement of upconversion luminescence was observed in the Er3+/Yb3+ codoped oxyfluoride glass ceramics, which may be due to the variation of coordination environment around Er3+ and Yb3+ ions after crystallization. The transition mechanisms of the green and red upconversion luminescence were ascribed to a two-photon process, and that of the blue upconversion luminescence was a three-photon process.
基金Project supported by National Science Foundation of China (51072190 and 11004177)Program for New Century Excellent Talents in University(NCET-07-0786)Zhejiang Provincial Natural Science Foundation of China (Z4100030 and Y4110621)
文摘Spectroscopic properties of Er3＋/Yb3＋-doped transparent oxyfluoride borosilicate glass ceramics containing YOF nanocrystals were systematically investigated. X-ray diffraction （XRD） confirmed the formation of YOF nanocrystals in the glassy matrix. Based on the Judd-Ofelt theory, the intensity parameters Ωi （i=2, 4, 6）, spontaneous emission probability, radiative lifetime, radiative quantum efficiency and the effective emission bandwidth were investigated. The upconversion luminescence intensity of Er3＋ ions in the glass ceramics increased significantly with the increasing crystallization temperature. The transition mechanisms of the green and red upconversion luminescence were ascribed to a two-photon process, and the blue upconversion luminescence was a three-photon absorption process.
基金financially supported by the National Natural Science Foundation of China (Nos. U1360202, 51472030, 51672024 and 51502014)the Fundamental Research Funds for the Central Universities (No. FRF-TP-16-027A3)the Innovation Project of Yunnan Province New Material Preparation and Processing Key Laboratory (No. 2016cx05)
文摘Municipal solid waste incineration(MSWI) fly ash is a by-product from municipal waste incineration.According to incomplete statistics, each year more than one million tons MSWI fly ash was produced in China. Owing to high heavy elements content, widely used disposal methods of landfill are not suitable for MSWI fly ash treatment. In this study, by using MSWI fly ash as raw materials, glassceramics was synthesized for the solidification of heavy metals and waste recycle. Process parameters, including composition, heat treatment temperature and time, were studied and optimized. Under optimizing conditions, the product has good properties of density of 3.42 g·cm^(-3) and Vickers hardness of 6.91 GPa. Moreover, the leaching concentration of heavy metal elements meets allowable values of toxicity characteristic leaching procedure(TCLP).This study offers an alternative for MSWI fly ash recycle.
基金the Science and Technology Support Projects of Sichuan Province (No. 2014GZ0011)the Industry Promotion Projects of Panzhihua in China (No.2013CY-C-2) for their financial support
文摘To effectively reuse high-titanium blast furnace slag （TS）, foam glass-ceramics were successfully prepared by powder sintering at 1000℃. TS and waste glass were used as the main raw materials, aluminium nitride （AIN） as the foaming agent, and borax as the fluxing agent. The influence of the amount of A1N added （lwt%-5wt%） on the crystalline phases, microstructure, and properties of the produced foam glass-ceramics was studied. The results showed that the main crystal phases were perovskite, diopside, and augite. With increasing A1N content, a transformation from diopside to augite occurred and the crystallinity of the pyroxene phases slightly decreased. Initially, the aver- age pore size and porosity of the foam glass-ceramics increased and subsequently decreased; similarly, their bulk density and compressive strength decreased and subsequently increased. The optimal properties were obtained when the foam glass-ceramics were prepared by adding 4wt% AIN.
文摘The crystallization behavior of wollastonite glass-ceramics was investigated by means of X-ray diffraction （XRD） analysis and surface morphological observations, and the chemical compositions were evaluated by field emission-scanning electron microscopy （FE-SEM） and energy dispersive X-ray spectroscopy （EDS）. Various heat treatment temperatures （850, 900, 950, 1000 and 1050 ℃） were used to obtain glass-ceramics of the ideal wollastonite crystal phase as well as optimum mechanical properties and chemical durability. From XRD, FE-SEM and EDS, the crystallization of acicular crystal phase in the matrix was achieved at heat treatment temperature of 1000 and 1050 ℃, and wollastonite （CaSiO3） was found in the acicular type main crystal phase in the glass-ceramics. Various properties, such as density, compressive strength, bending strength and chemical durability were also examined. The mechanical properties of glass-ceramics obtained at the heat treatment temperature of 1000 and 1050 ℃ were superior to those obtained at the heat treatment temperature of 850 ℃.
