In this letter, a route for synthesizing vertically aligned multi-walled carbon nanotubes（MWCNTs） with branched nanotubes in large area was reported. The branched MWCNTs up to about 30% can be generated by the pyrol...In this letter, a route for synthesizing vertically aligned multi-walled carbon nanotubes（MWCNTs） with branched nanotubes in large area was reported. The branched MWCNTs up to about 30% can be generated by the pyrolysis of iron（Ⅱ） phthalocyanine in presence of thiol under Ar/H2 at 800900℃. The growth mechanism of the branched nanotubes was proposed and the possible reason that thiol enhanced branched nanotubes growth is discussed. The as-prepared samples provide a suitable candidate to investigate the special electrical or thermal properties of CNTs with branched structures further.展开更多
We report the simultaneous enlarged growth of seven single crystal diamond(SCD) plates free from polycrystalline diamond(PCD) rim by using a microwave plasma chemical vapor deposition(MPCVD) system. Optical microscope...We report the simultaneous enlarged growth of seven single crystal diamond(SCD) plates free from polycrystalline diamond(PCD) rim by using a microwave plasma chemical vapor deposition(MPCVD) system. Optical microscope and atomic force microscope(AFM) show the typical step-bunching SCD morphology at the center, edge, and corner of the samples. The most aggressively expanding sample shows a top surface area three times of that of the substrate. The effective surface expanding is attributed to the utilization of the diamond substrates with(001) side surfaces, the spacial isolation of them to allow the sample surface expanding, and the adoption of the reported pocket holder. Nearly constant temperature of the diamond surfaces is maintained during growth by only decreasing the sample height, and thus all the other growth parameters can be kept unchanged to achieve high quality SCDs. The SCDs have little stress as shown by the Raman spectra. The full width at half maximum(FWHM) data of both the Raman characteristic peak and(004) x-ray rocking curve of the samples are at the same level as those of the standard CVD SCD from Element Six Ltd. The nonuniformity of the sample thickness or growth rate is observed, and photoluminescence spectra show that the nitrogen impurity increases with increasing growth rate. It is found that the reduction of the methane ratio in the sources gas flow from 5% to 3% leads to decrease of the vertical growth rate and increase of the lateral growth rate. This is beneficial to expand the top surface and improve the thickness uniformity of the samples. At last, the convenience of the growth method transferring to massive production has also been demonstrated by the successful simultaneous enlarged growth of 14 SCD samples.展开更多
A Zinc(II) complex of hexamethylenetetramine was prepared as a single source precursor and used to deposit zinc oxynitride thin films. The thin films were deposited on soda-lime glass substrates using the Metal Organi...A Zinc(II) complex of hexamethylenetetramine was prepared as a single source precursor and used to deposit zinc oxynitride thin films. The thin films were deposited on soda-lime glass substrates using the Metal Organic Chemical Vapour Deposition (MOCVD) technique at the deposition temperature of 370°C and 390°C, respectively. The Fourier Transform Infrared Spectroscopy (FTIR) was used to determine the functional groups in the precursor, with stretching frequency for O-H, N-H, and C-H observed. The deposited films were characterized using UV-Visible Spectroscopy, Scanning Electron Microscopy (SEM), Elemental diffraction X-ray (EDX), and X-ray Diffractometer (XRD). A direct bandgap of 3.15 eV and 3.18 eV was obtained from the film deposited at 370°C and 390°C, respectively, using the Envelope Method. In comparison, a bandgap of 3.19 eV and 3.21 eV was obtained using the absorption spectrum fitting (ASF) method. The SEM revealed that the film is homogeneous, dense, and compact, composed of cluster grains. The EDX confirmed the presence of Zinc, Nitrogen and Oxygen. The X-ray Diffraction indicated the polycrystalline nature of the film.展开更多
To investigate the microstructure and deposition mechanism of low-temperature isotropic pyrocarbon(LTIC),chemical vapour deposition was conducted in a steady-state fluidized bed using different propane concentrations ...To investigate the microstructure and deposition mechanism of low-temperature isotropic pyrocarbon(LTIC),chemical vapour deposition was conducted in a steady-state fluidized bed using different propane concentrations and deposition temperatures.The microstructure of LTIC obtained at different deposition conditions was characterized using scanning electron microscopy(SEM)and transmission electron microscopy(TEM).The results show that LTIC is composed of both globular-like and laminar structures.Increasing the deposition temperature is propitious for decreasing the nucleation barrier-forming pyrocarbon in vapour,causing the quantity of spherical particles with a smaller diameter to increase and the texture of the outer layer around carbon blacks inside the spherical particles to decrease gradually.Increasing the propane concentration also made the globular-like fracture morphology more obvious and caused the laminar structure to gradually disappear.Pyrocarbon formation is dominated by a surficial growth mechanism at lower propane concentrations,while gaseous nucleation mechanism is more dominant at higher propane concentrations.展开更多
Porous silicon carbide(SiC)has a specific biomorphous microstructure similar to the trabecular microstructure of human bone.Compared with that of bioactive ceramics,such as calcium phosphate,SiC does not induce sponta...Porous silicon carbide(SiC)has a specific biomorphous microstructure similar to the trabecular microstructure of human bone.Compared with that of bioactive ceramics,such as calcium phosphate,SiC does not induce spontaneous interface bonding to living bone.In this study,bioactive tantalum(Ta)metal deposited on porous SiC scaffolds by chemical vapour deposition was investigated to accelerate osseointegration and improve the bonding to bones.Scanning electron microscopy indicated that the Ta coating evenly covered the entire scaffold structure.Energy-dispersive spectroscopy and X-ray diffraction analysis showed that the coating consisted of Ta phases.The bonding strength between the Ta coating and the SiC substrate is 88.4MPa.The yield strength of porous SiC with a Ta coating(pTa)was 45.862.9MPa,the compressive strength was 61.463.2MPa and the elasticmodulus was4.8GPa.When MG-63 human osteoblasts were co-cultured with pTa,osteoblasts showed good adhesion and spreading on the surface of the pTa and its porous structure,which showed that it has excellent bioactivity and cyto-compatibility.To further study the osseointegration properties of pTa.PTa and porous titanium(pTi)were implanted into the femoral neck of goats for 12weeks,respectively.The Van-Gieson staining of histological sections results that the pTa group had better osseointegration than the pTi group.These results indicate that coating bioactive Ta metal on porous SiC scaffolds could be a potential material for bone substitutes.展开更多
We report a new scheme for fabrication of clean,suspended superconducting weak links from pristine single-walled carbon nanotubes(SWCNT).The SWCNTs were grown using the floating-catalyst chemical vapour deposition(FC-...We report a new scheme for fabrication of clean,suspended superconducting weak links from pristine single-walled carbon nanotubes(SWCNT).The SWCNTs were grown using the floating-catalyst chemical vapour deposition(FC-CVD)and directly deposited on top of prefabricated superconducting molybdenum-rhenium(MoRe)electrodes by thermophoresis at nearly ambient conditions.Transparent contacts to SWCNTs were obtained by vacuum-annealing the devices at 900℃,which enabled proximity-induced supercurrents up to 53 nA.SWCNT weak links fabricated on MoRe/palladium bilayer sustained supercurrents up to 0.4 nA after annealing at relatively low temperature of 220℃.The fabrication process does neither expose SWCNTs to lithographic chemicals,nor the contact electrodes to the harsh conditions of in situ CVD growth.Our scheme facilitates new experimental possibilities for hybrid superconducting devices.展开更多
1 Results There is an increasing demand for producing high performance ceramic films at a reduced cost. This paper describes an innovative and cost-effective method of producing nanostructured ceramic films based on E...1 Results There is an increasing demand for producing high performance ceramic films at a reduced cost. This paper describes an innovative and cost-effective method of producing nanostructured ceramic films based on Electrostatic Spray Assisted Vapour Deposition (ESAVD). ESAVD is a variant of chemical vapour deposition process which involves spraying atomised charged precursor droplets across an electric field where the precursor undergo decomposition and heterogeneous chemical reaction near the heat...展开更多
基金supported in part by grants from NSFC (51025207, 21173159)NSFZJ (R4090137)863 project (2012AA02A104)
文摘In this letter, a route for synthesizing vertically aligned multi-walled carbon nanotubes（MWCNTs） with branched nanotubes in large area was reported. The branched MWCNTs up to about 30% can be generated by the pyrolysis of iron（Ⅱ） phthalocyanine in presence of thiol under Ar/H2 at 800900℃. The growth mechanism of the branched nanotubes was proposed and the possible reason that thiol enhanced branched nanotubes growth is discussed. The as-prepared samples provide a suitable candidate to investigate the special electrical or thermal properties of CNTs with branched structures further.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2018YFB0406504 and 2016YFB0400105)the National Postdoctoral Program for Innovative Talents,China(Grant No.BX20190263)
文摘We report the simultaneous enlarged growth of seven single crystal diamond(SCD) plates free from polycrystalline diamond(PCD) rim by using a microwave plasma chemical vapor deposition(MPCVD) system. Optical microscope and atomic force microscope(AFM) show the typical step-bunching SCD morphology at the center, edge, and corner of the samples. The most aggressively expanding sample shows a top surface area three times of that of the substrate. The effective surface expanding is attributed to the utilization of the diamond substrates with(001) side surfaces, the spacial isolation of them to allow the sample surface expanding, and the adoption of the reported pocket holder. Nearly constant temperature of the diamond surfaces is maintained during growth by only decreasing the sample height, and thus all the other growth parameters can be kept unchanged to achieve high quality SCDs. The SCDs have little stress as shown by the Raman spectra. The full width at half maximum(FWHM) data of both the Raman characteristic peak and(004) x-ray rocking curve of the samples are at the same level as those of the standard CVD SCD from Element Six Ltd. The nonuniformity of the sample thickness or growth rate is observed, and photoluminescence spectra show that the nitrogen impurity increases with increasing growth rate. It is found that the reduction of the methane ratio in the sources gas flow from 5% to 3% leads to decrease of the vertical growth rate and increase of the lateral growth rate. This is beneficial to expand the top surface and improve the thickness uniformity of the samples. At last, the convenience of the growth method transferring to massive production has also been demonstrated by the successful simultaneous enlarged growth of 14 SCD samples.
文摘A Zinc(II) complex of hexamethylenetetramine was prepared as a single source precursor and used to deposit zinc oxynitride thin films. The thin films were deposited on soda-lime glass substrates using the Metal Organic Chemical Vapour Deposition (MOCVD) technique at the deposition temperature of 370°C and 390°C, respectively. The Fourier Transform Infrared Spectroscopy (FTIR) was used to determine the functional groups in the precursor, with stretching frequency for O-H, N-H, and C-H observed. The deposited films were characterized using UV-Visible Spectroscopy, Scanning Electron Microscopy (SEM), Elemental diffraction X-ray (EDX), and X-ray Diffractometer (XRD). A direct bandgap of 3.15 eV and 3.18 eV was obtained from the film deposited at 370°C and 390°C, respectively, using the Envelope Method. In comparison, a bandgap of 3.19 eV and 3.21 eV was obtained using the absorption spectrum fitting (ASF) method. The SEM revealed that the film is homogeneous, dense, and compact, composed of cluster grains. The EDX confirmed the presence of Zinc, Nitrogen and Oxygen. The X-ray Diffraction indicated the polycrystalline nature of the film.
基金National Natural Science Foundation of China,grant number:50975070grant sponsor:Zhejiang Provincial Science Foundation of China,grant number:LY12E05002
文摘To investigate the microstructure and deposition mechanism of low-temperature isotropic pyrocarbon(LTIC),chemical vapour deposition was conducted in a steady-state fluidized bed using different propane concentrations and deposition temperatures.The microstructure of LTIC obtained at different deposition conditions was characterized using scanning electron microscopy(SEM)and transmission electron microscopy(TEM).The results show that LTIC is composed of both globular-like and laminar structures.Increasing the deposition temperature is propitious for decreasing the nucleation barrier-forming pyrocarbon in vapour,causing the quantity of spherical particles with a smaller diameter to increase and the texture of the outer layer around carbon blacks inside the spherical particles to decrease gradually.Increasing the propane concentration also made the globular-like fracture morphology more obvious and caused the laminar structure to gradually disappear.Pyrocarbon formation is dominated by a surficial growth mechanism at lower propane concentrations,while gaseous nucleation mechanism is more dominant at higher propane concentrations.
基金supported by the National major research and invention programme of the thirteenth of China(no.2016YFC1102000)the Dalian Science and Technology Innovation Fund Project(no.2018J11CY030).
文摘Porous silicon carbide(SiC)has a specific biomorphous microstructure similar to the trabecular microstructure of human bone.Compared with that of bioactive ceramics,such as calcium phosphate,SiC does not induce spontaneous interface bonding to living bone.In this study,bioactive tantalum(Ta)metal deposited on porous SiC scaffolds by chemical vapour deposition was investigated to accelerate osseointegration and improve the bonding to bones.Scanning electron microscopy indicated that the Ta coating evenly covered the entire scaffold structure.Energy-dispersive spectroscopy and X-ray diffraction analysis showed that the coating consisted of Ta phases.The bonding strength between the Ta coating and the SiC substrate is 88.4MPa.The yield strength of porous SiC with a Ta coating(pTa)was 45.862.9MPa,the compressive strength was 61.463.2MPa and the elasticmodulus was4.8GPa.When MG-63 human osteoblasts were co-cultured with pTa,osteoblasts showed good adhesion and spreading on the surface of the pTa and its porous structure,which showed that it has excellent bioactivity and cyto-compatibility.To further study the osseointegration properties of pTa.PTa and porous titanium(pTi)were implanted into the femoral neck of goats for 12weeks,respectively.The Van-Gieson staining of histological sections results that the pTa group had better osseointegration than the pTi group.These results indicate that coating bioactive Ta metal on porous SiC scaffolds could be a potential material for bone substitutes.
基金This work was supported by the Academy of Finland projects 314448(BOLOSE)312295(CoE,Quantum Technology Finland)as well as by ERC(grant no.670743)+3 种基金The research also received partial funding from the European Union Seventh Framework Program FP7 Nanosciences,Nanotechnologies,Materials and new Production Technologies(FP7/2007-2013)under Grant Agreement No.604472(IRENA project)the Aalto Energy Efficiency(AEF)Research Program through the MOPPI projectIn addition,the research was partially supported by the Academy of Finland(Luonnontieteiden ja Tekniikan Tutkimuksen Toimikunta)via projects 286546(DEMEC)and 292600(SUPER)as well as by TEKES Finland via projects 3303/31/2015(cNT-PV)and 1882/31/2016(FEDOC).
文摘We report a new scheme for fabrication of clean,suspended superconducting weak links from pristine single-walled carbon nanotubes(SWCNT).The SWCNTs were grown using the floating-catalyst chemical vapour deposition(FC-CVD)and directly deposited on top of prefabricated superconducting molybdenum-rhenium(MoRe)electrodes by thermophoresis at nearly ambient conditions.Transparent contacts to SWCNTs were obtained by vacuum-annealing the devices at 900℃,which enabled proximity-induced supercurrents up to 53 nA.SWCNT weak links fabricated on MoRe/palladium bilayer sustained supercurrents up to 0.4 nA after annealing at relatively low temperature of 220℃.The fabrication process does neither expose SWCNTs to lithographic chemicals,nor the contact electrodes to the harsh conditions of in situ CVD growth.Our scheme facilitates new experimental possibilities for hybrid superconducting devices.
文摘1 Results There is an increasing demand for producing high performance ceramic films at a reduced cost. This paper describes an innovative and cost-effective method of producing nanostructured ceramic films based on Electrostatic Spray Assisted Vapour Deposition (ESAVD). ESAVD is a variant of chemical vapour deposition process which involves spraying atomised charged precursor droplets across an electric field where the precursor undergo decomposition and heterogeneous chemical reaction near the heat...
