A new synthetical method for nanomaterials was developed, and the semiconductor nanocrystalline CdS was fabricated through controlling of the living biomembrane in bean sprouts. The results indicated that approximatel...A new synthetical method for nanomaterials was developed, and the semiconductor nanocrystalline CdS was fabricated through controlling of the living biomembrane in bean sprouts. The results indicated that approximately spherical CdS particles about 5.1 nm, which has a cubic zinc blende structure with a cell constant a =0.581 8 nm, could be formed after the bean sprouts were successively soaked in 0 1 mol·L -1 Na 2S and 0 1 mol·L -1 CdCl 2 for 24 h. In addition, the tentative research for the reaction mechanism has been carried out. [WT5HZ]展开更多
A porosity-free and contamination-free surface layer with grain sizes ranging from nanometer to micrometer in Fe samples was obtained by surface mechanical attrition treatment (SMAT) technique. Mechanical and wear pro...A porosity-free and contamination-free surface layer with grain sizes ranging from nanometer to micrometer in Fe samples was obtained by surface mechanical attrition treatment (SMAT) technique. Mechanical and wear properties of the surface layer in the SMATed and annealed Fe samples were measured by means of nanoindentation and nanoscratch tests, respectively. Experimental results showed that the hardness of the surface layer in the SMATed Fe sample increased evidently due to the grain refinement. The elastic moduli of the surface layers in the SMATed and annealed Fe samples were unchanged, independent of grain size in the present grain size regime. Compared with the original Fe sample, the wear resistance enhanced and the coefficient of friction decreased in the surface layer of the SMATed Fe sample.展开更多
Nanocrystalline Trimanganese tetroxide (Mn3O4) was synthesized by solvothermal reaction of MnO2 and C2H5OH. The dependence of the Mn3O4 nanoparticle size on synthesis temperature was investigated using X-ray diffracti...Nanocrystalline Trimanganese tetroxide (Mn3O4) was synthesized by solvothermal reaction of MnO2 and C2H5OH. The dependence of the Mn3O4 nanoparticle size on synthesis temperature was investigated using X-ray diffraction (XRD) technique. The mechanism for the nanocrystallite growth was also studied. The results indicate that the prepared Mn3O4 has a nanocrystalline structure with XRD average crystal size varing from 54 to 70 nm depending on the synthesis temperature. The activation energy for the nanocrystallite growth was calculated to be 11.36 kJ·mol-1 according to the kinetic theory of nanocrystallite growth, indicating that Mn3O4 nanocrystallite grows primarily by means of an interfacial reaction during the solvothermal process.展开更多
The cerium ion(Ce4+) doped titania sol and nanocrystallites were prepared by chemical coprecipitation-peptization and hydrothermal synthesis methods, respectively. The X-ray diffraction pattern shows that Ce4+-TiO2 xe...The cerium ion(Ce4+) doped titania sol and nanocrystallites were prepared by chemical coprecipitation-peptization and hydrothermal synthesis methods, respectively. The X-ray diffraction pattern shows that Ce4+-TiO2 xerogel powder has semicrystalline structure and thermal sintering sample has crystalline structure. Ce4+-TiO2 nanocrystallites are composed of the major anatase phase titania (88.82 wt pct) and a small amount of crystalline cerium titanate. AFM micrograph shows that primary particle size of well-dispersed ultrafine sol particles is below 15 nm in diameter. The particle sizes are 30 nm for xerogel sample and 70 nm for nanocrystallites sample, which is different from the estimated values (2.41 nm and 4.53 nm) by XRD Scherrer's formula. The difference is mainly due to aggregation of nanocrystallites. The experimental results exhibit that photocatalysts of Ce4+-TiO2 sol and nanocrystallites have the ability to photodegrade reactive brilliant red dye (X-3B ) under visible light irradiation with the ion-TiO2/VIS/dye system. Moreover, Ce4+ doped titania sol has shown higher efficiency than the nanocrystallites sample in respect of potocatalytic activity. Meanwhile, dye photodegradation mechanisms are proposed to different photocatalytic reaction systems, which are dye photosensitization, ion-dye photosensitization and interband photocatalysis & dye photosensitization with respect to TiO2 nanocrystallites, Ce4+-TiO2 sol and Ce4+-TiO2 nanocrystallites system.展开更多
The nanopowders of SnO2 doped with different Eu^3＋ concentrations were synthesized using the modified Pechini method. The Eu^3＋ concentrations were high above solubility limit. The average size of crystallites was c...The nanopowders of SnO2 doped with different Eu^3＋ concentrations were synthesized using the modified Pechini method. The Eu^3＋ concentrations were high above solubility limit. The average size of crystallites was controlled by the sintering temperatures. The structure and the morphology of obtained powders were examined using the XRD （X-ray diffraction） and TEM （transmission electron microscopy） analyses. The Eu2Sn2O7 phase separation was observed at relatively high concentration of Eu^3＋ ions. The ZnS：Ag micropowders were mixed with the Eu^3＋：SnO2 powders and their normalized emission was used to measure a relative efficiency of Eu3＋：SnO〉 The photoluminescence spectra of mixed powders were measured in function of Eu^3＋ concentration and average size of nanocrystallites. The reference peak method was used for comparison of intensities of the samples and selection of optimal one. The influence of the average grain size and Eu^3＋ concentration on the phosphor＇s efficiency was discussed. The presented results confirmed the rightness of synthesis of the Eu^3＋：SnO2 in form of nanocrystalites with relatively high Eu^3＋ concentration.展开更多
The interracial Si nano-pyralnid-enhanced electroluminescence （EL） of an ITO/SiOx/p-Si/Al metal-oxidesemiconductor （MOS） diode with turn-on voltage of 50 V, threshold current of 1.23 mA/cm^2, output power of 16 nW...The interracial Si nano-pyralnid-enhanced electroluminescence （EL） of an ITO/SiOx/p-Si/Al metal-oxidesemiconductor （MOS） diode with turn-on voltage of 50 V, threshold current of 1.23 mA/cm^2, output power of 16 nW, and lifetime of 10 h is reported.展开更多
Barium titanate nanocrystallites were synthesized by a hydrothermal technique from barium chloride and tetrabutyl titanate. Single-crystalline cubic perovskite Ba TiO_3 consisting of spherical particles with diameters...Barium titanate nanocrystallites were synthesized by a hydrothermal technique from barium chloride and tetrabutyl titanate. Single-crystalline cubic perovskite Ba TiO_3 consisting of spherical particles with diameters ranging from 10 to 30 nm was easily achieved by this route. In order to study the influence of the synthesis process on the morphology and the optical properties, barium titanate was also prepared by a solid-state reaction. In this case, only the tetragonal phase which crystallizes above 900 was observed. High-temperature X-ray diffraction measurements were performed to investigate the crystallization temperatures as well as the particle sizes via the Scherrer formula. The lattice vibrations were evidenced by infrared spectroscopy. Eu^(3+)was used as a structural probe, and the luminescence properties recorded from Ba TiO_3 :Eu^(3+)and elaborated by a solid-state reaction and hydrothermal process were compared. The reddish emission of the europium is increased by the nanometric particles.展开更多
文摘A new synthetical method for nanomaterials was developed, and the semiconductor nanocrystalline CdS was fabricated through controlling of the living biomembrane in bean sprouts. The results indicated that approximately spherical CdS particles about 5.1 nm, which has a cubic zinc blende structure with a cell constant a =0.581 8 nm, could be formed after the bean sprouts were successively soaked in 0 1 mol·L -1 Na 2S and 0 1 mol·L -1 CdCl 2 for 24 h. In addition, the tentative research for the reaction mechanism has been carried out. [WT5HZ]
基金Financial support from the National Natural Science Foundation of China,the Ministry of Science and Technology of China(Grant G1999064505)NEDO International Joint Research Grant Program(01MB5)Ministry of Research of France(Grant 2001882,CPER EN2040)is acknowledged.
文摘A porosity-free and contamination-free surface layer with grain sizes ranging from nanometer to micrometer in Fe samples was obtained by surface mechanical attrition treatment (SMAT) technique. Mechanical and wear properties of the surface layer in the SMATed and annealed Fe samples were measured by means of nanoindentation and nanoscratch tests, respectively. Experimental results showed that the hardness of the surface layer in the SMATed Fe sample increased evidently due to the grain refinement. The elastic moduli of the surface layers in the SMATed and annealed Fe samples were unchanged, independent of grain size in the present grain size regime. Compared with the original Fe sample, the wear resistance enhanced and the coefficient of friction decreased in the surface layer of the SMATed Fe sample.
文摘Nanocrystalline Trimanganese tetroxide (Mn3O4) was synthesized by solvothermal reaction of MnO2 and C2H5OH. The dependence of the Mn3O4 nanoparticle size on synthesis temperature was investigated using X-ray diffraction (XRD) technique. The mechanism for the nanocrystallite growth was also studied. The results indicate that the prepared Mn3O4 has a nanocrystalline structure with XRD average crystal size varing from 54 to 70 nm depending on the synthesis temperature. The activation energy for the nanocrystallite growth was calculated to be 11.36 kJ·mol-1 according to the kinetic theory of nanocrystallite growth, indicating that Mn3O4 nanocrystallite grows primarily by means of an interfacial reaction during the solvothermal process.
基金supported by the Hi-Tech Research and Development Program(863 Program)of China(No.2002AA302304)the Nationa1 Natura1 Science Foundation of China(No.60121101)the Education Department Foundation of Jiangsu Province(JH01-010).
文摘The cerium ion(Ce4+) doped titania sol and nanocrystallites were prepared by chemical coprecipitation-peptization and hydrothermal synthesis methods, respectively. The X-ray diffraction pattern shows that Ce4+-TiO2 xerogel powder has semicrystalline structure and thermal sintering sample has crystalline structure. Ce4+-TiO2 nanocrystallites are composed of the major anatase phase titania (88.82 wt pct) and a small amount of crystalline cerium titanate. AFM micrograph shows that primary particle size of well-dispersed ultrafine sol particles is below 15 nm in diameter. The particle sizes are 30 nm for xerogel sample and 70 nm for nanocrystallites sample, which is different from the estimated values (2.41 nm and 4.53 nm) by XRD Scherrer's formula. The difference is mainly due to aggregation of nanocrystallites. The experimental results exhibit that photocatalysts of Ce4+-TiO2 sol and nanocrystallites have the ability to photodegrade reactive brilliant red dye (X-3B ) under visible light irradiation with the ion-TiO2/VIS/dye system. Moreover, Ce4+ doped titania sol has shown higher efficiency than the nanocrystallites sample in respect of potocatalytic activity. Meanwhile, dye photodegradation mechanisms are proposed to different photocatalytic reaction systems, which are dye photosensitization, ion-dye photosensitization and interband photocatalysis & dye photosensitization with respect to TiO2 nanocrystallites, Ce4+-TiO2 sol and Ce4+-TiO2 nanocrystallites system.
基金Project supported by Polish Ministry of Science and Higher Education (N507 076 32/2186, RO 02 015 02 and N507 421236)
文摘The nanopowders of SnO2 doped with different Eu^3＋ concentrations were synthesized using the modified Pechini method. The Eu^3＋ concentrations were high above solubility limit. The average size of crystallites was controlled by the sintering temperatures. The structure and the morphology of obtained powders were examined using the XRD （X-ray diffraction） and TEM （transmission electron microscopy） analyses. The Eu2Sn2O7 phase separation was observed at relatively high concentration of Eu^3＋ ions. The ZnS：Ag micropowders were mixed with the Eu^3＋：SnO2 powders and their normalized emission was used to measure a relative efficiency of Eu3＋：SnO〉 The photoluminescence spectra of mixed powders were measured in function of Eu^3＋ concentration and average size of nanocrystallites. The reference peak method was used for comparison of intensities of the samples and selection of optimal one. The influence of the average grain size and Eu^3＋ concentration on the phosphor＇s efficiency was discussed. The presented results confirmed the rightness of synthesis of the Eu^3＋：SnO2 in form of nanocrystalites with relatively high Eu^3＋ concentration.
文摘The interracial Si nano-pyralnid-enhanced electroluminescence （EL） of an ITO/SiOx/p-Si/Al metal-oxidesemiconductor （MOS） diode with turn-on voltage of 50 V, threshold current of 1.23 mA/cm^2, output power of 16 nW, and lifetime of 10 h is reported.
基金the financial support of the SEP-CONACYT(100764&178817)SIP-IPN(20130664 and 20130665) projectsthe financial support of this work by ECOSNord/ANUIES/CONACYT program number M09P01
文摘Barium titanate nanocrystallites were synthesized by a hydrothermal technique from barium chloride and tetrabutyl titanate. Single-crystalline cubic perovskite Ba TiO_3 consisting of spherical particles with diameters ranging from 10 to 30 nm was easily achieved by this route. In order to study the influence of the synthesis process on the morphology and the optical properties, barium titanate was also prepared by a solid-state reaction. In this case, only the tetragonal phase which crystallizes above 900 was observed. High-temperature X-ray diffraction measurements were performed to investigate the crystallization temperatures as well as the particle sizes via the Scherrer formula. The lattice vibrations were evidenced by infrared spectroscopy. Eu^(3+)was used as a structural probe, and the luminescence properties recorded from Ba TiO_3 :Eu^(3+)and elaborated by a solid-state reaction and hydrothermal process were compared. The reddish emission of the europium is increased by the nanometric particles.
