Titanium dioxide nanoparticles with an average diameter of about 10 nm are fabricated using a sintering method. The degradation of methyl orange indicates that the photocatalytic efficiency is greatly enhanced, which ...Titanium dioxide nanoparticles with an average diameter of about 10 nm are fabricated using a sintering method. The degradation of methyl orange indicates that the photocatalytic efficiency is greatly enhanced, which is measured to be 62.81%. Transmission electron microscopy is used to investigate the microstructure of TiO 2 nanoparticles in order to correlate their photocatalytic properties. High-resolution transmission electron microscopy examinations show that all the nanoparticles belong to the anatase phase, and pure edge dislocations exist in some nanoparticles. The great enhancement of photocatalytic efficiency is attributed to two factors, the quantum size effect and the surface defects in the nanoparticles.展开更多
The interfacial electrical potentials and charge distributions of two manganite-based heterojunctions, i.e.,La_(0.67)Ca_(0.33)MnO_3/SrTiO_3:0.05 wt% Nb(LCMO/STON) and La_(0.67)Ca_(0.33)MnO_3/LaMnO_3/SrTiO_3:0.05 wt% N...The interfacial electrical potentials and charge distributions of two manganite-based heterojunctions, i.e.,La_(0.67)Ca_(0.33)MnO_3/SrTiO_3:0.05 wt% Nb(LCMO/STON) and La_(0.67)Ca_(0.33)MnO_3/LaMnO_3/SrTiO_3:0.05 wt% Nb(simplified as LCMO/LMO/STON), are studied by means of off-axis electron holography in a transmission electron microscope.The influences of buffer layer on the microstructure and magnetic properties of the LCMO films are explored. The results show that when a buffer layer of LaMnO_3 is introduced, the tensile strain between the STON substrate and LCMO film reduces, misfit dislocation density decreases near the interfaces of the heterojunctions, and a positive magnetoresistance is observed. For the LCMO/STON junction, positive and negative charges accumulate near the interface between the substrate and the film. For the LCMO/LMO/STON junction, a complex charge distribution takes place across the interface, where notable negative charges accumulate. The difference between the charge distributions near the interface may shed light on the observed generation of positive magnetoresistance in the junction with a buffer layer.展开更多
A new modulated structure consisting of periodic(1120) stacking faults(SFs) in the α-Fe2O3nanowires(NWs)formed by the thermal oxidation of Fe foils is reported,using a combination of high-resolution transmission elec...A new modulated structure consisting of periodic(1120) stacking faults(SFs) in the α-Fe2O3nanowires(NWs)formed by the thermal oxidation of Fe foils is reported,using a combination of high-resolution transmission electron microscopy(HRTEM) observations and HRTEM image simulations.The periodicity of the modulated structure is 1.53 nm,which is ten times(3300) interplanar spacing and can be described by a shift of every ten(3300) planes with 1/2 the interplanar spacing of the(1120) plane.An atomic model for the Fe2O3structure is proposed to simulate the modulated structure.HRTEM simulation results confirm that the modulated structure in α-Fe2O3NWs is caused by SFs.展开更多
We report the transmission-electron microscopy study of the defects in wurtzitic GaN films grown on Si(111) substrates with AlN buffer layers by the metal-organic chemical vapour deposition method. The In0.1 Ga0.9N/...We report the transmission-electron microscopy study of the defects in wurtzitic GaN films grown on Si(111) substrates with AlN buffer layers by the metal-organic chemical vapour deposition method. The In0.1 Ga0.9N/GaN multiple quantum well (MQW) reduced the dislocation density by obstructing the mixed and screw dislocations passing through the MQW. No evident reduction of the edge dislocations density by the MQW was observed. It was found that dislocations with screw component can be located at the boundaries of sub-grains slightly in-plane misoriented.展开更多
The low temperature sample stage in a transmission electron microscope is used to investigate the charge ordering behaviours in a Bi 0.4 Ca 0.6 MnO 3 film with a thickness of 110 nm at 103 K.Six different types of sup...The low temperature sample stage in a transmission electron microscope is used to investigate the charge ordering behaviours in a Bi 0.4 Ca 0.6 MnO 3 film with a thickness of 110 nm at 103 K.Six different types of superlattice structures are observed using the selected-area electron diffraction(SAED) technique,while three of them match well with the modulation stripes in high-resolution transmission electron microscopy(HRTEM) images.It is found that the modulation periodicity and direction are completely different in the region close to the Bi 0.4 Ca 0.6 MnO 3 /SrTiO 3 interface from those in the region a little further from the Bi 0.4 Ca 0.6 MnO 3 /SrTiO 3 interface,and the possible reasons for this are discussed.Based on the experimental results,structural models are proposed for these localized modulated structures.展开更多
基金Project supported by the National Basic Research Program of China (Grant No. 2012CB722705)the Shandong Provincial Natural Science Foundation for Outstanding Young Scientists, China (Grant No.JQ201002)the Shandong Provincial Scientific Research Award for Outstanding Young and Middle-Aged Scientists,China (Grant No.BS2009CL0005)
文摘Titanium dioxide nanoparticles with an average diameter of about 10 nm are fabricated using a sintering method. The degradation of methyl orange indicates that the photocatalytic efficiency is greatly enhanced, which is measured to be 62.81%. Transmission electron microscopy is used to investigate the microstructure of TiO 2 nanoparticles in order to correlate their photocatalytic properties. High-resolution transmission electron microscopy examinations show that all the nanoparticles belong to the anatase phase, and pure edge dislocations exist in some nanoparticles. The great enhancement of photocatalytic efficiency is attributed to two factors, the quantum size effect and the surface defects in the nanoparticles.
基金Project supported by the National Natural Science Foundation of China(Grant No.10974105)the High-end Foreign Experts Recruitment Programs,China(Grant Nos.GDW20173500154 and GDW20163500110)+3 种基金the Taishan Scholar Program of Shandong ProvinceShandong Province "Double–Hundred Talent Plan" on 100 Foreign Experts and 100 Foreign Expert Teams Introduction Projectthe Top-notch Innovative Talent Program of Qingdao City,China(Grant No.13-CX-08)the Qingdao International Center for Semiconductor Photoelectric Nanomaterials,and Shandong Provincial University Key Laboratory of Optoelectrical Material Physics and Devices
文摘The interfacial electrical potentials and charge distributions of two manganite-based heterojunctions, i.e.,La_(0.67)Ca_(0.33)MnO_3/SrTiO_3:0.05 wt% Nb(LCMO/STON) and La_(0.67)Ca_(0.33)MnO_3/LaMnO_3/SrTiO_3:0.05 wt% Nb(simplified as LCMO/LMO/STON), are studied by means of off-axis electron holography in a transmission electron microscope.The influences of buffer layer on the microstructure and magnetic properties of the LCMO films are explored. The results show that when a buffer layer of LaMnO_3 is introduced, the tensile strain between the STON substrate and LCMO film reduces, misfit dislocation density decreases near the interfaces of the heterojunctions, and a positive magnetoresistance is observed. For the LCMO/STON junction, positive and negative charges accumulate near the interface between the substrate and the film. For the LCMO/LMO/STON junction, a complex charge distribution takes place across the interface, where notable negative charges accumulate. The difference between the charge distributions near the interface may shed light on the observed generation of positive magnetoresistance in the junction with a buffer layer.
基金Project supported by the National Key Basic Research Development Program of China (Grant No.2012CB722705)the Natural Science Foundation for Outstanding Young Scientists in Shandong Province,China (Grant No.JQ201002)+2 种基金the Program for Foreign Cultural and Educational Experts (Grant No.20123702083)the Program for Higher Education Science and Technology in Shandong Province (Grant No.J12LA17)Wang Yi-Qian would like to thank the financial support from Taishan Outstanding Overseas Scholar Program of Shandong Province,China
文摘A new modulated structure consisting of periodic(1120) stacking faults(SFs) in the α-Fe2O3nanowires(NWs)formed by the thermal oxidation of Fe foils is reported,using a combination of high-resolution transmission electron microscopy(HRTEM) observations and HRTEM image simulations.The periodicity of the modulated structure is 1.53 nm,which is ten times(3300) interplanar spacing and can be described by a shift of every ten(3300) planes with 1/2 the interplanar spacing of the(1120) plane.An atomic model for the Fe2O3structure is proposed to simulate the modulated structure.HRTEM simulation results confirm that the modulated structure in α-Fe2O3NWs is caused by SFs.
文摘We report the transmission-electron microscopy study of the defects in wurtzitic GaN films grown on Si(111) substrates with AlN buffer layers by the metal-organic chemical vapour deposition method. The In0.1 Ga0.9N/GaN multiple quantum well (MQW) reduced the dislocation density by obstructing the mixed and screw dislocations passing through the MQW. No evident reduction of the edge dislocations density by the MQW was observed. It was found that dislocations with screw component can be located at the boundaries of sub-grains slightly in-plane misoriented.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10974105 and 50832007)the Project of Introducing Talents to Support Thousand Talents Programs,China (Grant No. P201101032)+1 种基金the Program of Upgrading Technology for Scientific Instruments in Shandong Province,China (Grant No. 2011SJGZ16)the Program of Science and Technology in Qingdao City,China (Grant No. 11-2-4-23-hz)
文摘The low temperature sample stage in a transmission electron microscope is used to investigate the charge ordering behaviours in a Bi 0.4 Ca 0.6 MnO 3 film with a thickness of 110 nm at 103 K.Six different types of superlattice structures are observed using the selected-area electron diffraction(SAED) technique,while three of them match well with the modulation stripes in high-resolution transmission electron microscopy(HRTEM) images.It is found that the modulation periodicity and direction are completely different in the region close to the Bi 0.4 Ca 0.6 MnO 3 /SrTiO 3 interface from those in the region a little further from the Bi 0.4 Ca 0.6 MnO 3 /SrTiO 3 interface,and the possible reasons for this are discussed.Based on the experimental results,structural models are proposed for these localized modulated structures.
