Search results for "growth mechanism"
showing 3 items of 3 documents
Evidence of hexagonal WO3 structure stabilization on mica substrate
2009
International audience; WO3 nanorods are grown by a simple vapor deposition method on a mica substrate and characterized by Selected Area Electron Diffraction and Energy Dispersive X-rays Spectroscopy. Experimental results show the clear evidence of an unexpected WO3 hexagonal structure as well as an epitaxial growth on the mica substrate. Besides, potassium is evidenced inside the nanorods. It is thus deduced that a metastable WO3 hexagonal phase is stabilized by epitaxy through a tungsten bronze interlayer having same hexagonal structure.
Bi-2212 and Y123 highly curved single-crystal-like objects: whiskers, bows and ring-like structures
2012
High-temperature superconducting objects of Bi2Sr2CaCu2O8 and Y Ba2Cu3O7 highly curved in the ab-plane, such as curved/kinked whiskers, bows and ring-like structures, were obtained within a solid?liquid?solid (SLS) grass-like growth mechanism. As-grown objects are crystals with three-dimensional epitaxy similar to conventional single crystals: they can be viewed as crystal parts ?cut? from a conventional rectangular crystal. Between our curved objects and conventional crystals, whiskers or thin films there are some differences in the superconducting properties induced only by the shape factors and no new physics is observed. Some details of the growth mechanism are discussed, emphasizing cu…
Optimisation of metallic interconnects for hydrogen production by high temperature water vapour electrolysis
2012
For economical and environmental reasons, hydrogen is considered as a major energetic vector for the future. Hydrogen production via high temperature water vapour electrolysis (HTE) is a promising technology. A major technical difficulty related to high temperature water vapour electrolysis is the development of interconnects working efficiently for a long period. Working temperature of 800°C enables the use of metallic materials as interconnects. Chromia forming alloys are among the best candidates. The interconnect material chosen in the present study is a ferritic stainless steel with 18% chromium content. High temperature corrosion resistance and electrical conductivity of the alloy was…