TiO 2 nanowires were synthesized successfully in a large quantity by thermal evaporation using titanium monoxide powder as precursor. X-ray diffraction results showed that all the products were pure rutile phase of Ti...TiO 2 nanowires were synthesized successfully in a large quantity by thermal evaporation using titanium monoxide powder as precursor. X-ray diffraction results showed that all the products were pure rutile phase of TiO 2 . According to microstructural observations, the nanowires have two typical morphologies, a long straight type and a short tortuous type. The straight nanowires were obtained at a wide temperature range of 900–1050 ℃, while the tortuous ones were formed below 900 ℃. Transmission electron microscopy characterization revealed that both the straight and the tortuous nanowires are single-crystal rutile TiO 2 . The preferential growth direction of the nanowires was determined as [110] orientation according to electron diffraction and high-resolution image analyses. The morphological change of TiO 2 nanowires was discussed by considering the different atomic diffusion rates of Ti atoms caused by the phase transformation in Ti substrate at around 900 ℃.展开更多
Morphology,distribution and crystal structures of age-precipitated particles in practical Cu-bearing steels with ultra-low carbon were studied by high resolution electron microscopy（HREM）.The age-precipitation behav...Morphology,distribution and crystal structures of age-precipitated particles in practical Cu-bearing steels with ultra-low carbon were studied by high resolution electron microscopy（HREM）.The age-precipitation behavior was explored when poly-microalloying elements Cu,Nb,Cr,Mo and Ni were used and ε-Cu particles coexisted with carbides（carbonitrides） in steels.The fine dispersed ε-Cu particles and carbides of microalloying element Nb,Cr,Mo being about 10 nm only in size were observed in peak aging specimens and over-aging specimens.The twin structures and stacking faults in the particles and the transient structures formed in the early stage of the particle precipitation were also observed.The crystal structure of three types of age-precipitation particles was firstly identified by lattice streaks in HREM images of the single particles.The experimental method identifying crystal structure of fine and dispersed particles using HREM images of single particle was proposed.展开更多
基金supported by the Hundred Talents Program of the Chinese Academy of Sciences,Shenyang Science and Technology Project (Grant No.F11-264-1-65)the National Basic Research Program of China (Grant No. 2010CB631006)the Major National Science and Technology Program of China (GrantNo. 2011ZX02602)
文摘TiO 2 nanowires were synthesized successfully in a large quantity by thermal evaporation using titanium monoxide powder as precursor. X-ray diffraction results showed that all the products were pure rutile phase of TiO 2 . According to microstructural observations, the nanowires have two typical morphologies, a long straight type and a short tortuous type. The straight nanowires were obtained at a wide temperature range of 900–1050 ℃, while the tortuous ones were formed below 900 ℃. Transmission electron microscopy characterization revealed that both the straight and the tortuous nanowires are single-crystal rutile TiO 2 . The preferential growth direction of the nanowires was determined as [110] orientation according to electron diffraction and high-resolution image analyses. The morphological change of TiO 2 nanowires was discussed by considering the different atomic diffusion rates of Ti atoms caused by the phase transformation in Ti substrate at around 900 ℃.
基金supported by the National High-Tech Research and Development Program of China ("863 Program", Grant Nos. 2007AA03A228 and 2005AA305G70)
文摘Morphology,distribution and crystal structures of age-precipitated particles in practical Cu-bearing steels with ultra-low carbon were studied by high resolution electron microscopy（HREM）.The age-precipitation behavior was explored when poly-microalloying elements Cu,Nb,Cr,Mo and Ni were used and ε-Cu particles coexisted with carbides（carbonitrides） in steels.The fine dispersed ε-Cu particles and carbides of microalloying element Nb,Cr,Mo being about 10 nm only in size were observed in peak aging specimens and over-aging specimens.The twin structures and stacking faults in the particles and the transient structures formed in the early stage of the particle precipitation were also observed.The crystal structure of three types of age-precipitation particles was firstly identified by lattice streaks in HREM images of the single particles.The experimental method identifying crystal structure of fine and dispersed particles using HREM images of single particle was proposed.
