Spreading behavior of molybdenum trioxide on alumina and silica: A Raman microscopy study
1990; Elsevier BV; Volume: 124; Issue: 2 Linguagem: Inglês
10.1016/0021-9517(90)90183-k
ISSN1090-2694
Autores Tópico(s)Semiconductor materials and devices
ResumoTje wetting of alumina by molybdenum trioxide has been demonstrated by Raman microscopy. Special specimens, which consisted of an alumina wafer in contact with a molybdenum trioxide wafer, were prepared for this purpose. Concentration profiles across the sharp dividing line between the two oxides were measured with a Raman microscope after thermal treatment at 800 K in a stream of dry O2 or O2 saturated with water vapor. The molybdenum oxide was transported over the alumina surface for several hundred micrometers. In contrast, in a similar wafer with silica no transport of molybdenum oxide could be observed. The results suggest that neither gas-phase transport nor surface diffusion in a concentration gradient provide major contributions to the spreading process. A solid-solid wetting process is considered to best describe the observed phenomena, the decrease in surface free energy being the dominant driving force for the spreading of molybdenum oxide over alumina.
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