Novel ZnO microbowls are successfully synthesized by the thermal evaporating of a mixture of ZnS powder and Zn powder. The morphologies of the as-synthesized products can be adjusted by changing the temperature and th...Novel ZnO microbowls are successfully synthesized by the thermal evaporating of a mixture of ZnS powder and Zn powder. The morphologies of the as-synthesized products can be adjusted by changing the temperature and the type of substrate. The morphologies, microstructures, and photoluminescence properties are investigated by X-ray diffraction, Raman spectroscopy, scanning electron microscope, and photoluminescence spectroscopy respectively. The growth mechanism of the as-synthesized ZnO microbowls is proposed based on the experimental results. ZnO microbowls presented here can be used as building blocks to fabricate optical and optoelectronic micro/nano devices.展开更多
Core-shell structured SiC@SiO_(2)nanowires and Si@SiO_(2)nanowires were prepared on the surface of carbon/carbon(C/C)composites by a thermal evaporation method using SiO powders as the silicon source and Ni(NO3)2 as t...Core-shell structured SiC@SiO_(2)nanowires and Si@SiO_(2)nanowires were prepared on the surface of carbon/carbon(C/C)composites by a thermal evaporation method using SiO powders as the silicon source and Ni(NO3)2 as the catalyst.The average diameters of SiC@SiO_(2)nanowires and Si@SiO_(2)nanowires are about 145 nm,and the core-shell diameter ratios are about 0.41 and 0.53,respectively.The SiO_(2)shells of such two nanowires resulted from the reaction between SiO and CO and the reaction of SiO itself,respectively,based on the model analysis.The growth of these two nanowires conformed to the vapor-liquid-solid(VLS)mode.In this mode,CO played an important role in the growth of nanowires.There existed a critical partial pressure of CO(pC)determining the microstructure evolution of nanowires into whether SiC@SiO_(2)or Si@SiO_(2).The value of pC was calculated to be 4.01×10^(-15) Pa from the thermodynamic computation.Once the CO partial pressure in the system was greater than the pC,SiO tended to react with CO,causing the formation of SiC@SiO_(2)nanowires.However,the decomposition of SiO played a predominant role and the products mainly consisted of Si@SiO_(2)nanowires.This work may be helpful for the regulation of the growth process and the understanding of the growth mechanism of silicon-based nanowires.展开更多
The vacuum thermal evaporation technique was used to simultaneously deposit zinc coatings onto interstitial free steel plates and single-crystal silicon wafers in a high vacuum environment.The effect of substrate temp...The vacuum thermal evaporation technique was used to simultaneously deposit zinc coatings onto interstitial free steel plates and single-crystal silicon wafers in a high vacuum environment.The effect of substrate temperature on the mor-phology and crystal orientation of zinc coatings was investigated.When the substrate temperature was 25 and 50℃,the zinc crystallites were plate-like and grew under a particular angle to the substrate surface.After the substrate was heated to 100℃,the zinc crystallites were regular hexagonal and arranged almost parallel to the substrate surface.In addition,observation of pure zinc coatings with different thicknesses showed that the growth of zinc coating was mainly in the Volmer-Weber mode.When the process parameters were appropriate,the zinc coating was composed of closely arranged columnar crystallites,and the crystallites grew preferentially along[0001]direction.展开更多
This paper reports a novel helix-like ZnO nanostructure with several tens of nanometres in thickness synthesized on a gold-coated Si substrate by thermal evaporation of zinc sulfide powder at 1020℃. Transmission elec...This paper reports a novel helix-like ZnO nanostructure with several tens of nanometres in thickness synthesized on a gold-coated Si substrate by thermal evaporation of zinc sulfide powder at 1020℃. Transmission electron microscope characterization shows that as-synthesized ZnO nanohelices extend along [0111] direction and the axial direction of the helix is along [0001] direction. A catalyst-intervened dislocation-induced growth mechanism has been suggested to explain the formation of the helix-like ZnO nanostructures. This study opens a new route to construct helix-like ZnO nanostructures by different evaporation sources.展开更多
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
With Zn(NO3)2·6H2O and NaOH as starting materials, a novel nest-like ZnO nanostructure was successfully synthesized by a solvo-thermal method. The products were characterized by X-ray diffraction, photoluminescen...With Zn(NO3)2·6H2O and NaOH as starting materials, a novel nest-like ZnO nanostructure was successfully synthesized by a solvo-thermal method. The products were characterized by X-ray diffraction, photoluminescence and scanning electron microscopy. The growth mechanism of the nest-like ZnO was discussed. The results show that the as-synthesized samples have a wurtzite structure, with a weak UV emission at about 395 nm, a green emission at around 557 nm and a blue-green emission at 453 nm. SEM investigation reveals that the growth route of the nest-like ZnO can be considered involving three stages: nano-sized ZnO sheet can be firstly achieved, then outspreads quickly and increasingly becomes a long fishbone-like strip with many branch sheets, and finally these sheets curl into a nest-like structure.展开更多
基金Project supported by the Foundation for Key Project of Ministry of Education, China (Grant No. 211046)the Open Fund of State Key Laboratory for the Modification of Chemical Fibers and Polymer Materials, Dong Hua University, China (Grant No. K1012)+1 种基金the Program for New Century Excellent Talents in Heilongjiang Provincial University, China (Grant No. 1252-NCET-018)the Program for Scientific and Technological Innovation Team Construction in the Universities of Heilongjiang,China (GrantNo. 2011TD010)
文摘Novel ZnO microbowls are successfully synthesized by the thermal evaporating of a mixture of ZnS powder and Zn powder. The morphologies of the as-synthesized products can be adjusted by changing the temperature and the type of substrate. The morphologies, microstructures, and photoluminescence properties are investigated by X-ray diffraction, Raman spectroscopy, scanning electron microscope, and photoluminescence spectroscopy respectively. The growth mechanism of the as-synthesized ZnO microbowls is proposed based on the experimental results. ZnO microbowls presented here can be used as building blocks to fabricate optical and optoelectronic micro/nano devices.
基金This work was supported by the National Natural Science Foundation of China(Nos.52061135102,52101098)Innovation Talent Promotion Plan of Shaanxi Province for Science and Technology Innovation Team(No.2020TD-003)+2 种基金Young Talents for Science and Technology Association supported by Shaanxi Province(No.20200406)the Fund of Key Laboratory of National Defense Science and Technology in Northwestern Polytechnical University(No.JCKYS2020607003)Innovation and Entrepreneurship Training Program for College Students(No.202110699088).
文摘Core-shell structured SiC@SiO_(2)nanowires and Si@SiO_(2)nanowires were prepared on the surface of carbon/carbon(C/C)composites by a thermal evaporation method using SiO powders as the silicon source and Ni(NO3)2 as the catalyst.The average diameters of SiC@SiO_(2)nanowires and Si@SiO_(2)nanowires are about 145 nm,and the core-shell diameter ratios are about 0.41 and 0.53,respectively.The SiO_(2)shells of such two nanowires resulted from the reaction between SiO and CO and the reaction of SiO itself,respectively,based on the model analysis.The growth of these two nanowires conformed to the vapor-liquid-solid(VLS)mode.In this mode,CO played an important role in the growth of nanowires.There existed a critical partial pressure of CO(pC)determining the microstructure evolution of nanowires into whether SiC@SiO_(2)or Si@SiO_(2).The value of pC was calculated to be 4.01×10^(-15) Pa from the thermodynamic computation.Once the CO partial pressure in the system was greater than the pC,SiO tended to react with CO,causing the formation of SiC@SiO_(2)nanowires.However,the decomposition of SiO played a predominant role and the products mainly consisted of Si@SiO_(2)nanowires.This work may be helpful for the regulation of the growth process and the understanding of the growth mechanism of silicon-based nanowires.
文摘The vacuum thermal evaporation technique was used to simultaneously deposit zinc coatings onto interstitial free steel plates and single-crystal silicon wafers in a high vacuum environment.The effect of substrate temperature on the mor-phology and crystal orientation of zinc coatings was investigated.When the substrate temperature was 25 and 50℃,the zinc crystallites were plate-like and grew under a particular angle to the substrate surface.After the substrate was heated to 100℃,the zinc crystallites were regular hexagonal and arranged almost parallel to the substrate surface.In addition,observation of pure zinc coatings with different thicknesses showed that the growth of zinc coating was mainly in the Volmer-Weber mode.When the process parameters were appropriate,the zinc coating was composed of closely arranged columnar crystallites,and the crystallites grew preferentially along[0001]direction.
基金Project supported by National Key Basic Research Project (Grant No 2003CB716900)Doctor Start-up Fund of Harbin Normal University (Grant No KGB200802)+1 种基金Natural Science Foundation of Heilongjiang Province (Grant No B2007-2)the Science Technology and Research Project of Education Bureau, Heilongjiang Province (Grant No 11531229)
文摘This paper reports a novel helix-like ZnO nanostructure with several tens of nanometres in thickness synthesized on a gold-coated Si substrate by thermal evaporation of zinc sulfide powder at 1020℃. Transmission electron microscope characterization shows that as-synthesized ZnO nanohelices extend along [0111] direction and the axial direction of the helix is along [0001] direction. A catalyst-intervened dislocation-induced growth mechanism has been suggested to explain the formation of the helix-like ZnO nanostructures. This study opens a new route to construct helix-like ZnO nanostructures by different evaporation sources.
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the Research Foundation of Education Bureau of Sichuan Province of China (10ZB066)the Natural Science Foundation of Southwest Petroleum University of China (2010XJZ197)
基金ACKNOWLEDGMENTS This work was supported by the Natural Science Foundation of Fujian Province of China （No.2007J0317 and No.JB06104） and the Key project of Fujian Provincial Department of Science and Technology （No.2007H0019）.
基金Projects(09JCYBJC04200, 05yfJMTC 12900) supported by the Natural Science Foundation of Tianjin, China
文摘With Zn(NO3)2·6H2O and NaOH as starting materials, a novel nest-like ZnO nanostructure was successfully synthesized by a solvo-thermal method. The products were characterized by X-ray diffraction, photoluminescence and scanning electron microscopy. The growth mechanism of the nest-like ZnO was discussed. The results show that the as-synthesized samples have a wurtzite structure, with a weak UV emission at about 395 nm, a green emission at around 557 nm and a blue-green emission at 453 nm. SEM investigation reveals that the growth route of the nest-like ZnO can be considered involving three stages: nano-sized ZnO sheet can be firstly achieved, then outspreads quickly and increasingly becomes a long fishbone-like strip with many branch sheets, and finally these sheets curl into a nest-like structure.
