Study of the Oxides of Copper Formed in Air
1955; De Gruyter; Volume: 10; Issue: 2 Linguagem: Inglês
10.1515/zna-1955-0208
ISSN1865-7109
Autores Tópico(s)Chemical and Physical Properties of Materials
ResumoOxides of copper formed in air at temperatures between 150°C and 1030°C, and for times of formation up to one hour have been studied. Their composition, structure by electron reflection and rectification - all these as a function of the thickness of the film - have been investigated. At first small crystallites of Cu 2 O are formed, then they increase in size and get oriented. These crystallites of Cu 2 O gradually change over to those of CuO showing a three ring pattern, definite orientation and finally a fibrous structure. At high temperatures and appreciable times of formation a layer of Cu 2 O is formed below the CuO layer. Rectification of CuO films showing orientation and of the composite film Cu 2 O + CuO has been studied in detail. A plausible mechanism for the formation of the various oxides is suggested. The following special points have been observed: (1) Cu 2 O changes into CuO, crystallite by crystallite, (2) The three ring pattern is due to oriented monoclinic CuO, (3) CuO oriented shows a small rectification in a direction opposite to that of Cu 2 O, (4) At high temperatures, when a change of orientation of CuO can occur, a Cu 2 O film is formed below the CuO film, (5) The composite layer Cu 2 O + CuO shows a rectification comparable with Cu 2 O but with a higher voltage response.
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