Sphere-shape Eu（DBM）3Phen@Si02 nanoparticles were fabricated by employing a modified alkaline catalyzed hydrolysis and precipitation method. The silica coated on the particles surface was obtained by means of hydrol...Sphere-shape Eu（DBM）3Phen@Si02 nanoparticles were fabricated by employing a modified alkaline catalyzed hydrolysis and precipitation method. The silica coated on the particles surface was obtained by means of hydrolysis and condensation of tetraethyl orthosilicate （TEOS）. In this study, the particles morphology was analyzed by scanning electron microscopy （SEM） and the surface composition of samples was characterized by X-ray diffraction （XRD） and Fourier transform infrared spectroscopy （FT-IR）. It is confirmed that the Si02 shell has been coated on the rare earth complexes successfully. Moreover, the near-infrared photoluminescence emission analysis on the nanoparticles showed that the SiO2 shell would increase the luminescence intensity of Eu（DBM）3Phen. This is primarily due to the reason that SiO2 shell with chemical inertness can effectively reduce the ion Eu3~ non-radiation transition probabilities, as well as the probability of rare earth luminescence quenching caused by the external medium.展开更多
This paper reports that the film composed of flower-like ZnO micro-spheres, which consists of nano-sheets, is fab- ricated by chemical bath deposition. By adding hydrogen fluoride （HF） into the reaction solution, wh...This paper reports that the film composed of flower-like ZnO micro-spheres, which consists of nano-sheets, is fab- ricated by chemical bath deposition. By adding hydrogen fluoride （HF） into the reaction solution, which contains zinc nitrate hexahydrate and hexamethylenetetramine, the ZnO crystal growth process is changed and the film composed by ZnO micro-spheres is obtained after keeping the reaction solution at 95 ℃ for 2 h. The morphology, crystal phase and wettahility of the sample axe characterized by scanning electron microscope, x-ray diffraction and contact angle meter, respectively. The results show that the filrrl has the micro-nano compound structure. After modification with heptadecafluorodecyltrimethoxy-silane, the wettability of the film changed from superhydrophilicity to superhydropho-bicity, on which water contact angle and the sliding angle are 154° and less than 5° for 8-μL water droplet, respectively. Additionally, the formation mechanism of the ZnO micro-sphere is also discussed.展开更多
We investigate the dynamic crystallization processes of colloidal photonic crystals, which are potentially invaluable for solving a number of existing and emerging technical problems in regards to controlled fabricati...We investigate the dynamic crystallization processes of colloidal photonic crystals, which are potentially invaluable for solving a number of existing and emerging technical problems in regards to controlled fabrication of crystals, such as size normalization, stability improvement, and acceleration of synthesis. In this paper, we report systematic high-resolution optical observation of the spontaneous crystallization of monodisperse polystyrene(PS) micro-spheres in aqueous solution into close-packed arrays in a static line optical tweezers. The experiments demonstrate that the crystal structure is mainly affected by the minimum potential energy of the system; however, the crystallization dynamics could be affected by various mechanical, physical, and geometric factors. The complicated dynamic transformation process from 1D crystallization to 2D crystallization and the creation and annihilation of dislocations and defects via crystal relaxation are clearly illustrated.Two major crystal growth modes, the epitaxy growth pattern and the inserted growth pattern, have been identified to play a key role in shaping the dynamics of the 1D and 2D crystallization process. These observations offer invaluable insights for in-depth research about colloidal crystal crystallization.展开更多
By means of distillation precipitation polymerization,the silica-hybrid particles with polyazobenzene shell (PAzo@SiO2) microspheres were prepared with 6-(4-methoxy-4'-oxy-azobenzene) hexyl methacrylate (Azo-M) as...By means of distillation precipitation polymerization,the silica-hybrid particles with polyazobenzene shell (PAzo@SiO2) microspheres were prepared with 6-(4-methoxy-4'-oxy-azobenzene) hexyl methacrylate (Azo-M) as monomer,divinylbenzene (DVB) as cross-linker,and ～250 nm vinylated sol-gel silica particles as template. Hollow polyazobenzene microspheres were further developed after selective removal of the silica cores with HF solution. When the content of DVB related to Azo-M is 20 wt%,the acetonitrile is 200 mL,and the polymerization time is 4.5 h,the hollow PAzo microspheres with about 20 nm shell are successfully fabricated. These hollow PAzo microspheres have excellent reversible photoisomerization,and their first-order rate constant of trans-cis isomerization only decreases 11.8% compared with homopolymer of azobenzene (Homo-PAzo).展开更多
This research has focused on the treatment of zinc flue dust by an acid leach process, combining an environmentally suitable impurity removal process to recover cadmium. Optimum conditions were found as follows： H2SO...This research has focused on the treatment of zinc flue dust by an acid leach process, combining an environmentally suitable impurity removal process to recover cadmium. Optimum conditions were found as follows： H2SO4 concentration 90 g/L, liquid/solid ratio 6：1, leaching temperature 60 ℃ and leaching time 1.0 h. Under these conditions, 95.8% cadmium was recovered. FeAsO4 and Fe（OH）3 precipitates with FeCI3 are found to be highly effective to obtain a high degree of separation of heavy metals and the oxyanions of arsenic from the leachate. The overall separation of arsenic and other heavy metals and precipitate settling rates are optimum at n（Fe）/n（As） ratio of 3：l and pH 6. The removal rates ofFe, Pb and Cu from the solution were greater than 98.9%, and As removal rate was 99.6%. A solvent extraction with P204 was used for the separation of zinc and cadmium. Optimum conditions are obtained as follows： 20% P204 （volume fraction） diluted with kerosene at room temperature, pH 3.0, and varying organic/aqueous （O/A） phase ratio 1：1. The extraction rate of zinc is 99.2% under these conditions. Spherical cadmium particles showing nearly uniform size were produced by hydrogen reduction at 310 ℃ and the crystal structure was cubic. In addition, the purity of the recovered cadmium powder is more than 99.99%.展开更多
With narrow red photoluminescence (PL) bands, tetravalent Mn^(4+) doped phosphors show promising prospect in commercial application to effectively expand color gamut of phosphor converted LED displays. Here, we report...With narrow red photoluminescence (PL) bands, tetravalent Mn^(4+) doped phosphors show promising prospect in commercial application to effectively expand color gamut of phosphor converted LED displays. Here, we report a type of Sr_(2-z)Mg_(1+y)Y_(z)Al_(22-x)O_(36):xMn^(4+) phosphors with regular cage-like micro-spherical morphologies. The micron size spherical precursors were synthesized with a propylene oxide (PO) driven fast sol–gel method. The cage -like spherical morphology is beneficial to efficiently trapping much incident light to enhance the PL of the phosphors. Being calcined at 1300 ℃, Sr_(2)MgAl_(21.978)O_(36):0.022Mn^(4+) only exhibits the internal quantum efficiency (IQE) of 24.91%. With the Mg^(2+)-Mn^(4+) codoping and Y^(3+)/Sr^(2+) substituting strategies, to fulfill charge balance and produce John-Teller distortion, IQE of Sr_(2-z)Mg_(1+y)Y_(z)Al_(22-x)O_(36):xMn^(4+) can be further improved up to 36.45%. The CIE color coordinates of Sr_(2-z)Mg_(1+y)Y_(z)Al_(22-x)O_(36):xMn^(4+) under near ultraviolet excitation can be stably fixed to (0.723, 0.227) at deep red region. It thus finds a potential application as pc-LED display with much broader color gamut than that of the NTSC standard. Therefore, Sr_(2-z)Mg_(1+y)Y_(z)Al_(22-x)O_(36):xMn^(4+) micron size spheres can be employed as promising red phosphors for high performance LED displays.展开更多
基金financial support from the National Natural Science Foundation of China (No. 60972134, No. 51205137)the Fundamental Research Funds for the Central Universities with grant no. 2012ZM0067
文摘Sphere-shape Eu（DBM）3Phen@Si02 nanoparticles were fabricated by employing a modified alkaline catalyzed hydrolysis and precipitation method. The silica coated on the particles surface was obtained by means of hydrolysis and condensation of tetraethyl orthosilicate （TEOS）. In this study, the particles morphology was analyzed by scanning electron microscopy （SEM） and the surface composition of samples was characterized by X-ray diffraction （XRD） and Fourier transform infrared spectroscopy （FT-IR）. It is confirmed that the Si02 shell has been coated on the rare earth complexes successfully. Moreover, the near-infrared photoluminescence emission analysis on the nanoparticles showed that the SiO2 shell would increase the luminescence intensity of Eu（DBM）3Phen. This is primarily due to the reason that SiO2 shell with chemical inertness can effectively reduce the ion Eu3~ non-radiation transition probabilities, as well as the probability of rare earth luminescence quenching caused by the external medium.
基金Project supported by the National Natural Science Foundation of China (Grant No. 50872129)Natural Science Foundation of Anhui Province of China (Grant No. 070414187)
文摘This paper reports that the film composed of flower-like ZnO micro-spheres, which consists of nano-sheets, is fab- ricated by chemical bath deposition. By adding hydrogen fluoride （HF） into the reaction solution, which contains zinc nitrate hexahydrate and hexamethylenetetramine, the ZnO crystal growth process is changed and the film composed by ZnO micro-spheres is obtained after keeping the reaction solution at 95 ℃ for 2 h. The morphology, crystal phase and wettahility of the sample axe characterized by scanning electron microscope, x-ray diffraction and contact angle meter, respectively. The results show that the filrrl has the micro-nano compound structure. After modification with heptadecafluorodecyltrimethoxy-silane, the wettability of the film changed from superhydrophilicity to superhydropho-bicity, on which water contact angle and the sliding angle are 154° and less than 5° for 8-μL water droplet, respectively. Additionally, the formation mechanism of the ZnO micro-sphere is also discussed.
基金National 973 Program of China(2013CB632704)National Natural Science Foundation of China(NSFC)(11434017)
文摘We investigate the dynamic crystallization processes of colloidal photonic crystals, which are potentially invaluable for solving a number of existing and emerging technical problems in regards to controlled fabrication of crystals, such as size normalization, stability improvement, and acceleration of synthesis. In this paper, we report systematic high-resolution optical observation of the spontaneous crystallization of monodisperse polystyrene(PS) micro-spheres in aqueous solution into close-packed arrays in a static line optical tweezers. The experiments demonstrate that the crystal structure is mainly affected by the minimum potential energy of the system; however, the crystallization dynamics could be affected by various mechanical, physical, and geometric factors. The complicated dynamic transformation process from 1D crystallization to 2D crystallization and the creation and annihilation of dislocations and defects via crystal relaxation are clearly illustrated.Two major crystal growth modes, the epitaxy growth pattern and the inserted growth pattern, have been identified to play a key role in shaping the dynamics of the 1D and 2D crystallization process. These observations offer invaluable insights for in-depth research about colloidal crystal crystallization.
基金supported by the Outstanding Youth Fund of the National Natural Science Foundation of China (50825301)Open Fund of State Key Laboratory of Plastic Forming Simulation and Die & Mould Technology of HUST
文摘By means of distillation precipitation polymerization,the silica-hybrid particles with polyazobenzene shell (PAzo@SiO2) microspheres were prepared with 6-(4-methoxy-4'-oxy-azobenzene) hexyl methacrylate (Azo-M) as monomer,divinylbenzene (DVB) as cross-linker,and ～250 nm vinylated sol-gel silica particles as template. Hollow polyazobenzene microspheres were further developed after selective removal of the silica cores with HF solution. When the content of DVB related to Azo-M is 20 wt%,the acetonitrile is 200 mL,and the polymerization time is 4.5 h,the hollow PAzo microspheres with about 20 nm shell are successfully fabricated. These hollow PAzo microspheres have excellent reversible photoisomerization,and their first-order rate constant of trans-cis isomerization only decreases 11.8% compared with homopolymer of azobenzene (Homo-PAzo).
文摘This research has focused on the treatment of zinc flue dust by an acid leach process, combining an environmentally suitable impurity removal process to recover cadmium. Optimum conditions were found as follows： H2SO4 concentration 90 g/L, liquid/solid ratio 6：1, leaching temperature 60 ℃ and leaching time 1.0 h. Under these conditions, 95.8% cadmium was recovered. FeAsO4 and Fe（OH）3 precipitates with FeCI3 are found to be highly effective to obtain a high degree of separation of heavy metals and the oxyanions of arsenic from the leachate. The overall separation of arsenic and other heavy metals and precipitate settling rates are optimum at n（Fe）/n（As） ratio of 3：l and pH 6. The removal rates ofFe, Pb and Cu from the solution were greater than 98.9%, and As removal rate was 99.6%. A solvent extraction with P204 was used for the separation of zinc and cadmium. Optimum conditions are obtained as follows： 20% P204 （volume fraction） diluted with kerosene at room temperature, pH 3.0, and varying organic/aqueous （O/A） phase ratio 1：1. The extraction rate of zinc is 99.2% under these conditions. Spherical cadmium particles showing nearly uniform size were produced by hydrogen reduction at 310 ℃ and the crystal structure was cubic. In addition, the purity of the recovered cadmium powder is more than 99.99%.
基金Project supported by the National Natural Science Foundation of China (51872255,51672243)。
文摘With narrow red photoluminescence (PL) bands, tetravalent Mn^(4+) doped phosphors show promising prospect in commercial application to effectively expand color gamut of phosphor converted LED displays. Here, we report a type of Sr_(2-z)Mg_(1+y)Y_(z)Al_(22-x)O_(36):xMn^(4+) phosphors with regular cage-like micro-spherical morphologies. The micron size spherical precursors were synthesized with a propylene oxide (PO) driven fast sol–gel method. The cage -like spherical morphology is beneficial to efficiently trapping much incident light to enhance the PL of the phosphors. Being calcined at 1300 ℃, Sr_(2)MgAl_(21.978)O_(36):0.022Mn^(4+) only exhibits the internal quantum efficiency (IQE) of 24.91%. With the Mg^(2+)-Mn^(4+) codoping and Y^(3+)/Sr^(2+) substituting strategies, to fulfill charge balance and produce John-Teller distortion, IQE of Sr_(2-z)Mg_(1+y)Y_(z)Al_(22-x)O_(36):xMn^(4+) can be further improved up to 36.45%. The CIE color coordinates of Sr_(2-z)Mg_(1+y)Y_(z)Al_(22-x)O_(36):xMn^(4+) under near ultraviolet excitation can be stably fixed to (0.723, 0.227) at deep red region. It thus finds a potential application as pc-LED display with much broader color gamut than that of the NTSC standard. Therefore, Sr_(2-z)Mg_(1+y)Y_(z)Al_(22-x)O_(36):xMn^(4+) micron size spheres can be employed as promising red phosphors for high performance LED displays.
