Sr2Al2SiO7：Ce^3＋, Tb^3＋ white emitting phosphors were fabricated using the sol-gel method. X-Ray Powder Diffraction （XRD） analysis confirmed the formation of Sr2Al2SiO7：Ce^3＋, Tb^3＋. Scanning Electron Microsco...Sr2Al2SiO7：Ce^3＋, Tb^3＋ white emitting phosphors were fabricated using the sol-gel method. X-Ray Powder Diffraction （XRD） analysis confirmed the formation of Sr2Al2SiO7：Ce^3＋, Tb^3＋. Scanning Electron Microscopy （SEM） observation indicated that the microstructure of the phosphor consisted of regular fine grains with an average size of about 0.5-1 μm. Luminescence properties were analyzed by measuring the photoluminescence spectra. The Ce^3＋, Tb^3＋-codoped Sr2Al2SiO7 phosphors showed four main emission peaks： one at 414 nm for Ce^3＋ and three at 482, 543, and 588 nm for Tb^3＋. The emission spectra of the samples with different doping concentrations showed that the Tb^3＋ emission was dominant because of the persistent energy transfer from Ce^3＋. The decay characteristic was better than that prepared by the solid-state process in the comparable condition. The codoped phosphor displayed long persistent white phosphorescence.展开更多
SiO 2-GeO 2 sols and gel glass coatings with different contents of germanium dioxide were fabricated.Stable and transparent sols could only be obtained when the content of GeO 2 was under 35%.It is shown by SEM tha...SiO 2-GeO 2 sols and gel glass coatings with different contents of germanium dioxide were fabricated.Stable and transparent sols could only be obtained when the content of GeO 2 was under 35%.It is shown by SEM that only one continuous phase is observed in the coating of 65SiO 2·35GeO 2 and plenty of Ge,O and Si were all found in it.However,the separated phase is found in the coating of 60SiO 2·40GeO 2 and a large number of Ge and O.It is proved by the Raman scattering investigation that the separated phase in the coating of 60SiO 2·40GeO 2 is germanium dioxide.The congeries of hydrolystates of Cl 3GeCH 2CH 2COOH play the main role in the formation of the separated phase when the proportion of GeO 2 is much higher.Si-O-Ge,Si-O-Si,and Ge-O-Ge bonds form in the coating of 65SiO 2·35GeO 2 and this coating is homogenous.展开更多
M-type hexaferrites BaLaxFe12-xO19 powders were synthesized by sol-gel method in the presence of SiO2 nanoparticles. The X-ray diffraction patterns of BaLaxFe12-xO19/SiO2 calcined at 1000℃manifest that all the specie...M-type hexaferrites BaLaxFe12-xO19 powders were synthesized by sol-gel method in the presence of SiO2 nanoparticles. The X-ray diffraction patterns of BaLaxFe12-xO19/SiO2 calcined at 1000℃manifest that all the species have hexagonal crystal structure and no diffraction peaks of SiO2 are found. The structure of BaLaxFe12-xO19 seems uniform at different La doping dosage. Fourier transform infrared (FTIR) proves the co-existence of SiO2 and ferrites in the produc-ts. The addition of SiO2 nanoparticles promotes the formation of more homogeneous and finer ferrite crystal, as proved by scanning electron microscopy (SEM). Compared with BaLa0.5Fe11.5O19 powders synthesized without SiO2 nanoparticles, those synthesized in the presence of SiO2 nanoparticles present in smaller powder size and similar structure.展开更多
The present study involves the preparation of TiO 2/ SiO 2nanocrystals and their application in self-cleaning wool-polyester fabrics.The TiO 2/ SiO 2nanocrystals were successfully synthesized and deposited onto wool-p...The present study involves the preparation of TiO 2/ SiO 2nanocrystals and their application in self-cleaning wool-polyester fabrics.The TiO 2/ SiO 2nanocrystals were successfully synthesized and deposited onto wool-polyester fabrics using the low-temperature sol-gel technique.The as-prepared nanocomposites and the nanocomposites coated samples were characterized by X-ray diffraction( XRD) and scanning electron microscopy( SEM),respectively.The XRD and SEM results showed that the single-phase anatase nanocrystallites were formed and loaded on the fabric surface successfully.The photocatalytic activities of TiO 2-coated and TiO 2/ SiO 2-coated wool-polyester fabrics were measured by studying photodegradation of methylene blue dye.Comparison of the photocatalytic activity of the coated samples reveals superiority of TiO 2/ SiO 2modified sample with respect to that of pure TiO 2modified sample.Our observations indicate that by applying this technique to the fabrics,self-cleaning materials can be designed for practical application.展开更多
Al-doped and B, Al-codoped silica xerogel was fabricated by sol-gel process. The influence of B ions and annealing temperature on luminescent properties of phosphors were studied by using fluorescence spectrum, X-ray ...Al-doped and B, Al-codoped silica xerogel was fabricated by sol-gel process. The influence of B ions and annealing temperature on luminescent properties of phosphors were studied by using fluorescence spectrum, X-ray diffraction, DSC, TG/DTG analysis and IR spectrum. The heat treatment has a large effect on the luminescent properties. Under 248 nm excitation, the emission spectrum of samples heated shows characteristic emission peaks of Eu^3＋ ions are, which are due to the transitions of ^5D0→^7FJ（J = 0, 1, 2, 3, 4） of Eu^3＋ , respectively. The transition of ^5D0→^7F1 is split into two peaks.展开更多
(Fe7Co3)0.15(SiO2)0.85 granular alloy solid was prepared successfully using sol-gel method. The samples with different reducing temperatures were investigated by X-ray diffractometer(XRD),transmission electron microgr...(Fe7Co3)0.15(SiO2)0.85 granular alloy solid was prepared successfully using sol-gel method. The samples with different reducing temperatures were investigated by X-ray diffractometer(XRD),transmission electron micrography(TEM) and vibrating sample magnetometer(VSM). The av-erage particIe sizes of the samples were also calculated from Scherrer formula. The magnetic properties of (Fe7Co3 )o. 15 (SiO2)0.85 were studied in detail.展开更多
The luminophors MeO-SiO_2:Eu^(3+),Bi^(3+)and MeO-SiO_2Bi^(3+)(Me=Mg.Sr)were synthesized at relatively lower temperature by the sol-gel method using the silica sol as a source of silica.The optimum composition and synt...The luminophors MeO-SiO_2:Eu^(3+),Bi^(3+)and MeO-SiO_2Bi^(3+)(Me=Mg.Sr)were synthesized at relatively lower temperature by the sol-gel method using the silica sol as a source of silica.The optimum composition and synthesis conditions were obtained by studying the excitation and emission spectra and the effects of energy transfer from the Bi^(3+)ions to the Eu^(3+)ions.展开更多
基金the National Natural Science Foundation of China (20376009)the Liaoning Natural Science Foundation (20032129) of China
文摘Sr2Al2SiO7：Ce^3＋, Tb^3＋ white emitting phosphors were fabricated using the sol-gel method. X-Ray Powder Diffraction （XRD） analysis confirmed the formation of Sr2Al2SiO7：Ce^3＋, Tb^3＋. Scanning Electron Microscopy （SEM） observation indicated that the microstructure of the phosphor consisted of regular fine grains with an average size of about 0.5-1 μm. Luminescence properties were analyzed by measuring the photoluminescence spectra. The Ce^3＋, Tb^3＋-codoped Sr2Al2SiO7 phosphors showed four main emission peaks： one at 414 nm for Ce^3＋ and three at 482, 543, and 588 nm for Tb^3＋. The emission spectra of the samples with different doping concentrations showed that the Tb^3＋ emission was dominant because of the persistent energy transfer from Ce^3＋. The decay characteristic was better than that prepared by the solid-state process in the comparable condition. The codoped phosphor displayed long persistent white phosphorescence.
文摘SiO 2-GeO 2 sols and gel glass coatings with different contents of germanium dioxide were fabricated.Stable and transparent sols could only be obtained when the content of GeO 2 was under 35%.It is shown by SEM that only one continuous phase is observed in the coating of 65SiO 2·35GeO 2 and plenty of Ge,O and Si were all found in it.However,the separated phase is found in the coating of 60SiO 2·40GeO 2 and a large number of Ge and O.It is proved by the Raman scattering investigation that the separated phase in the coating of 60SiO 2·40GeO 2 is germanium dioxide.The congeries of hydrolystates of Cl 3GeCH 2CH 2COOH play the main role in the formation of the separated phase when the proportion of GeO 2 is much higher.Si-O-Ge,Si-O-Si,and Ge-O-Ge bonds form in the coating of 65SiO 2·35GeO 2 and this coating is homogenous.
基金Project supported by Fund for Harbin Young Scholars (2005AFQ X J 0 31)
文摘M-type hexaferrites BaLaxFe12-xO19 powders were synthesized by sol-gel method in the presence of SiO2 nanoparticles. The X-ray diffraction patterns of BaLaxFe12-xO19/SiO2 calcined at 1000℃manifest that all the species have hexagonal crystal structure and no diffraction peaks of SiO2 are found. The structure of BaLaxFe12-xO19 seems uniform at different La doping dosage. Fourier transform infrared (FTIR) proves the co-existence of SiO2 and ferrites in the produc-ts. The addition of SiO2 nanoparticles promotes the formation of more homogeneous and finer ferrite crystal, as proved by scanning electron microscopy (SEM). Compared with BaLa0.5Fe11.5O19 powders synthesized without SiO2 nanoparticles, those synthesized in the presence of SiO2 nanoparticles present in smaller powder size and similar structure.
基金the Fundamental Research Funds for the Central Universities,China，China Postdoctoral Science
文摘The present study involves the preparation of TiO 2/ SiO 2nanocrystals and their application in self-cleaning wool-polyester fabrics.The TiO 2/ SiO 2nanocrystals were successfully synthesized and deposited onto wool-polyester fabrics using the low-temperature sol-gel technique.The as-prepared nanocomposites and the nanocomposites coated samples were characterized by X-ray diffraction( XRD) and scanning electron microscopy( SEM),respectively.The XRD and SEM results showed that the single-phase anatase nanocrystallites were formed and loaded on the fabric surface successfully.The photocatalytic activities of TiO 2-coated and TiO 2/ SiO 2-coated wool-polyester fabrics were measured by studying photodegradation of methylene blue dye.Comparison of the photocatalytic activity of the coated samples reveals superiority of TiO 2/ SiO 2modified sample with respect to that of pure TiO 2modified sample.Our observations indicate that by applying this technique to the fabrics,self-cleaning materials can be designed for practical application.
文摘Al-doped and B, Al-codoped silica xerogel was fabricated by sol-gel process. The influence of B ions and annealing temperature on luminescent properties of phosphors were studied by using fluorescence spectrum, X-ray diffraction, DSC, TG/DTG analysis and IR spectrum. The heat treatment has a large effect on the luminescent properties. Under 248 nm excitation, the emission spectrum of samples heated shows characteristic emission peaks of Eu^3＋ ions are, which are due to the transitions of ^5D0→^7FJ（J = 0, 1, 2, 3, 4） of Eu^3＋ , respectively. The transition of ^5D0→^7F1 is split into two peaks.
文摘(Fe7Co3)0.15(SiO2)0.85 granular alloy solid was prepared successfully using sol-gel method. The samples with different reducing temperatures were investigated by X-ray diffractometer(XRD),transmission electron micrography(TEM) and vibrating sample magnetometer(VSM). The av-erage particIe sizes of the samples were also calculated from Scherrer formula. The magnetic properties of (Fe7Co3 )o. 15 (SiO2)0.85 were studied in detail.
文摘The luminophors MeO-SiO_2:Eu^(3+),Bi^(3+)and MeO-SiO_2Bi^(3+)(Me=Mg.Sr)were synthesized at relatively lower temperature by the sol-gel method using the silica sol as a source of silica.The optimum composition and synthesis conditions were obtained by studying the excitation and emission spectra and the effects of energy transfer from the Bi^(3+)ions to the Eu^(3+)ions.
