Free-standing diamond films have been successfully deposited on stainless steel substrates using microwave plasma-assisted chemical vapor deposition. Although iron, which is the main element of stainless steel, is kno...Free-standing diamond films have been successfully deposited on stainless steel substrates using microwave plasma-assisted chemical vapor deposition. Although iron, which is the main element of stainless steel, is known to inhibit the nucleation of diamond and enhance the formation of graphite, we were able to grow relatively thick films （-1.2 mm）. The films were easily detachable from the substrates. The poor adhesion made it possible to obtain free-standing diamond films without chemical etching. Raman spectroscopy showed the 1332 cm^-1 characteristic Raman peak of diamond and the 1580 cm^-1, 1350 cm^-1 bands of graphite on the growth surface and backside of the films, respectively. By energy dispersive X-ray spectroscopy it was only possible to detect iron on the back of the films, but not on the surface. The role of iron in the film growth is discussed.展开更多
The paper presents a study on the cohesion of volcanic ash particles using surface free energy determination and zeta potential analyses.This is a subject of great interest in physical volcanology,as many researches o...The paper presents a study on the cohesion of volcanic ash particles using surface free energy determination and zeta potential analyses.This is a subject of great interest in physical volcanology,as many researches on volcanic particle aggregation are frequently reported.In this case,special attention is paid to the role of structural or hydration forces between hydrophilic surfaces,which are a consequence of the electron-donor/electron-acceptor character of the interface.From this point of view,the results are potentially interesting as they could give valuable insights into this process.The results are presented in terms of the total energy of interaction between dispersed particles,computed from the extended DLVO theory.Contributions to the total free energy of interaction were determined from the zeta potential and surface free energy of ash,measured under different experimental conditions.Two samples of basaltic volcanic ash(black and white)with silica contents of 44% and 63% respectively are studied.The surface free energy and zeta potential were analysed for ashes immersed in different electrolytes(NaCl,CaCl,FeCl).The presence of electrolytes changes the surface properties of the solid materials.The analysis of total interaction energy between the ash particles in aqueous medium shows that soil cohesion strongly depends on ash surface properties,chemical nature,the adsorbed cation on the surface,and p H value.展开更多
The porous TiOz film was self-assembled on the surface of electrophoretic-deposited titanate nanoribbon film without the addition of templates by using TiF4 as the precursor. It was found that the hydrolysis of TiF4 w...The porous TiOz film was self-assembled on the surface of electrophoretic-deposited titanate nanoribbon film without the addition of templates by using TiF4 as the precursor. It was found that the hydrolysis of TiF4 was accompanied with the self-assembly processes of TiO2 nanoparticles on the surface of electrophoretic-deposited titanate nanoribbon film, resulting in the formation of porous TiO2 structures. Titanate nanoribbon film was demonstrated to provide the active sites for the effective self-assembly of porous TiO2 nanostructures owing to a large amount of hydroxyl groups. Compared with the nonporous TiO2 film, the prepared porous TiO2 films obviously showed an enhanced photocatalytic activity, which could be attributed to the rapider diffusion and more efficient transport of various reactants and products during photocatalytic reaction in the t^orous structures.展开更多
文摘Free-standing diamond films have been successfully deposited on stainless steel substrates using microwave plasma-assisted chemical vapor deposition. Although iron, which is the main element of stainless steel, is known to inhibit the nucleation of diamond and enhance the formation of graphite, we were able to grow relatively thick films （-1.2 mm）. The films were easily detachable from the substrates. The poor adhesion made it possible to obtain free-standing diamond films without chemical etching. Raman spectroscopy showed the 1332 cm^-1 characteristic Raman peak of diamond and the 1580 cm^-1, 1350 cm^-1 bands of graphite on the growth surface and backside of the films, respectively. By energy dispersive X-ray spectroscopy it was only possible to detect iron on the back of the films, but not on the surface. The role of iron in the film growth is discussed.
基金partially funded by two projects:the MEDSUV project from the European Union Seventh Framework Programme(FP7)under Grant No.308665the Spanish Government(Project CGL2011-29499-C02-01)
文摘The paper presents a study on the cohesion of volcanic ash particles using surface free energy determination and zeta potential analyses.This is a subject of great interest in physical volcanology,as many researches on volcanic particle aggregation are frequently reported.In this case,special attention is paid to the role of structural or hydration forces between hydrophilic surfaces,which are a consequence of the electron-donor/electron-acceptor character of the interface.From this point of view,the results are potentially interesting as they could give valuable insights into this process.The results are presented in terms of the total energy of interaction between dispersed particles,computed from the extended DLVO theory.Contributions to the total free energy of interaction were determined from the zeta potential and surface free energy of ash,measured under different experimental conditions.Two samples of basaltic volcanic ash(black and white)with silica contents of 44% and 63% respectively are studied.The surface free energy and zeta potential were analysed for ashes immersed in different electrolytes(NaCl,CaCl,FeCl).The presence of electrolytes changes the surface properties of the solid materials.The analysis of total interaction energy between the ash particles in aqueous medium shows that soil cohesion strongly depends on ash surface properties,chemical nature,the adsorbed cation on the surface,and p H value.
基金Funded by the National Natural Science Foundation of China (20803055,51102087)the Major Science and Technology Program for Water Pollution Control and Treatment (2009ZX07106-003)the Fundamental Research Funds for the Central Universities (2011-1a-039,2011-1a-043)
文摘The porous TiOz film was self-assembled on the surface of electrophoretic-deposited titanate nanoribbon film without the addition of templates by using TiF4 as the precursor. It was found that the hydrolysis of TiF4 was accompanied with the self-assembly processes of TiO2 nanoparticles on the surface of electrophoretic-deposited titanate nanoribbon film, resulting in the formation of porous TiO2 structures. Titanate nanoribbon film was demonstrated to provide the active sites for the effective self-assembly of porous TiO2 nanostructures owing to a large amount of hydroxyl groups. Compared with the nonporous TiO2 film, the prepared porous TiO2 films obviously showed an enhanced photocatalytic activity, which could be attributed to the rapider diffusion and more efficient transport of various reactants and products during photocatalytic reaction in the t^orous structures.
