The synthesis of carbon nanotubes￡¨CNTs ￡(c)at low temperature has received a gre at deal of attention and be-comes a challenging issue￡(r)But few mo del which accounts for the growth of C NTs is suited for th...The synthesis of carbon nanotubes￡¨CNTs ￡(c)at low temperature has received a gre at deal of attention and be-comes a challenging issue￡(r)But few mo del which accounts for the growth of C NTs is suited for the synthesis of CNTs by microwave plasma chemical vapor deposition￡¨MWPCVD￡(c)at low temperature because most rese archers conclude that the growth mechanism is determi ned by the catalyst-supporter interaction while ignored the diffusion o f carbon in the catalyst￡(r)In this paper,under the catalytic effect of cobalt supported by SiO 2 and Al 2 O 3 ,CNTs are synthe-sized by MWPCVD at about 500℃,and tip-growth,the model which accounts fo r the catalytic growth of CNTs is outlined￡(r)It is the temperature difference between the upper and bottom o f the catalytic particle that results in the diffusion of carbon atoms from upper to the bottom,and precipitation of s aturated carbon on the bottom surface to form CNTs￡(r)展开更多
Growth of carbon nanotubes (CNTs) at low temperature is very important to the ap- plications of nanotubes. In this paper, under the catalytic effect of cobalt nanoparticles supported by SiO2, CNTs were synthesized by ...Growth of carbon nanotubes (CNTs) at low temperature is very important to the ap- plications of nanotubes. In this paper, under the catalytic effect of cobalt nanoparticles supported by SiO2, CNTs were synthesized by microwave plasma chemical vapor deposition (MWPCVD) below 500°C. lt demonstrates that MWPCVD can be a very efficient process for the synthesis of CNTs at low temperature.展开更多
Diamond thin films were prepared in a modified quartz bell-jar type microwave chemical vapor deposition (MWPCVD) system. The influences of process parameters on MWPCVD diamond thin films quality such as substrate pre...Diamond thin films were prepared in a modified quartz bell-jar type microwave chemical vapor deposition (MWPCVD) system. The influences of process parameters on MWPCVD diamond thin films quality such as substrate pretreatment, deposition gas ratio, deposition pressure and substrate position were examined and studied. The deposited films were characterized by using Scanning electron microscopy(SEM) and Raman spectroscopy. It was shown that this quartz bell-jar type MWPCVD system is beneficial to the deposition of high quality diamond thin films.展开更多
Carbon nanotubes (CNTs) are synthesized from methane and hydrogen gas mixture directly on stainless steel plates by microwave plasma chemical vapor deposition (MWPCVD).By varying pretreatment conditions of the substra...Carbon nanotubes (CNTs) are synthesized from methane and hydrogen gas mixture directly on stainless steel plates by microwave plasma chemical vapor deposition (MWPCVD).By varying pretreatment conditions of the substrates such as mechanically polishing and acid washing,it is found the polishing and acid washing can lower the turn-on field and improve the emission current density.The current density of the un-pretreated sample attains 1.2mA/cm 2,but the polished sample and polished acidly washed sample attain 3.2 and 2.75mA/cm 2,respectively,at the electric field of 6.25V/μm.展开更多
文摘The synthesis of carbon nanotubes￡¨CNTs ￡(c)at low temperature has received a gre at deal of attention and be-comes a challenging issue￡(r)But few mo del which accounts for the growth of C NTs is suited for the synthesis of CNTs by microwave plasma chemical vapor deposition￡¨MWPCVD￡(c)at low temperature because most rese archers conclude that the growth mechanism is determi ned by the catalyst-supporter interaction while ignored the diffusion o f carbon in the catalyst￡(r)In this paper,under the catalytic effect of cobalt supported by SiO 2 and Al 2 O 3 ,CNTs are synthe-sized by MWPCVD at about 500℃,and tip-growth,the model which accounts fo r the catalytic growth of CNTs is outlined￡(r)It is the temperature difference between the upper and bottom o f the catalytic particle that results in the diffusion of carbon atoms from upper to the bottom,and precipitation of s aturated carbon on the bottom surface to form CNTs￡(r)
文摘Growth of carbon nanotubes (CNTs) at low temperature is very important to the ap- plications of nanotubes. In this paper, under the catalytic effect of cobalt nanoparticles supported by SiO2, CNTs were synthesized by microwave plasma chemical vapor deposition (MWPCVD) below 500°C. lt demonstrates that MWPCVD can be a very efficient process for the synthesis of CNTs at low temperature.
文摘Diamond thin films were prepared in a modified quartz bell-jar type microwave chemical vapor deposition (MWPCVD) system. The influences of process parameters on MWPCVD diamond thin films quality such as substrate pretreatment, deposition gas ratio, deposition pressure and substrate position were examined and studied. The deposited films were characterized by using Scanning electron microscopy(SEM) and Raman spectroscopy. It was shown that this quartz bell-jar type MWPCVD system is beneficial to the deposition of high quality diamond thin films.
文摘Carbon nanotubes (CNTs) are synthesized from methane and hydrogen gas mixture directly on stainless steel plates by microwave plasma chemical vapor deposition (MWPCVD).By varying pretreatment conditions of the substrates such as mechanically polishing and acid washing,it is found the polishing and acid washing can lower the turn-on field and improve the emission current density.The current density of the un-pretreated sample attains 1.2mA/cm 2,but the polished sample and polished acidly washed sample attain 3.2 and 2.75mA/cm 2,respectively,at the electric field of 6.25V/μm.
