Ultrafine powders containing alumina nanowires are synthesized by DC arc plasma from pure aluminium metal. Nanowires grow only when reactive gases are composed of nitrogen and less than ten percent of oxygen. Nanowire...Ultrafine powders containing alumina nanowires are synthesized by DC arc plasma from pure aluminium metal. Nanowires grow only when reactive gases are composed of nitrogen and less than ten percent of oxygen. Nanowires have the diameters ranging from 20 to 80 nm and lengths ranging from hundreds nanometers to tens of micrometers. A first assumption of the mechanism process is proposed, in which nanowires grow starting directly from the aluminium. Photoluminescence measurements show that the powders have three emission peaks around 435, 530 and 750 nm resulting from different kinds of defects such as oxygen vacancies, aluminium interstitial ions and surface defects.展开更多
Amorphous Si_(1-x)Sn_x alloys have been prepared by co-evaporation onto substrates maintained at liquid nitrogen temperature. Their atomic structure is investigated using density measurements, scanning high-energy ele...Amorphous Si_(1-x)Sn_x alloys have been prepared by co-evaporation onto substrates maintained at liquid nitrogen temperature. Their atomic structure is investigated using density measurements, scanning high-energy electron diffraction and Mossbauer spectroscopy. The optical and electrical properties are reported. Then, a method to hydrogenate the films during the evaporation process is described and applied to the preparation of amorphous semiconductors from pure silicon to pure tin. Finally, multilayers of type Si / Si:H / ... or Si:H / Si:D / ... are studied. The modulation of hydrogen is shown by low-angle neutron scattering and measurements of hydrogen diffusivity are presented.展开更多
文摘Ultrafine powders containing alumina nanowires are synthesized by DC arc plasma from pure aluminium metal. Nanowires grow only when reactive gases are composed of nitrogen and less than ten percent of oxygen. Nanowires have the diameters ranging from 20 to 80 nm and lengths ranging from hundreds nanometers to tens of micrometers. A first assumption of the mechanism process is proposed, in which nanowires grow starting directly from the aluminium. Photoluminescence measurements show that the powders have three emission peaks around 435, 530 and 750 nm resulting from different kinds of defects such as oxygen vacancies, aluminium interstitial ions and surface defects.
文摘Amorphous Si_(1-x)Sn_x alloys have been prepared by co-evaporation onto substrates maintained at liquid nitrogen temperature. Their atomic structure is investigated using density measurements, scanning high-energy electron diffraction and Mossbauer spectroscopy. The optical and electrical properties are reported. Then, a method to hydrogenate the films during the evaporation process is described and applied to the preparation of amorphous semiconductors from pure silicon to pure tin. Finally, multilayers of type Si / Si:H / ... or Si:H / Si:D / ... are studied. The modulation of hydrogen is shown by low-angle neutron scattering and measurements of hydrogen diffusivity are presented.
