Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10620304 | Acta Materialia | 2013 | 10 Pages |
Abstract
Polycrystalline fluorine-doped SnO2 thin films with a given thickness of about 250 nm have been grown by ultrasonic spray pyrolysis with a growth temperature in the range of 360-480 °C. A texture transition from ã1 0 1ã to ã1 0 0ã and ã3 0 1ã crystallographic orientations has experimentally been found by X-ray diffraction measurements as growth temperature is raised, revealing that a process of abnormal grain growth has occurred. The texture effects have been investigated within a thermodynamic approach considering that grain growth is driven by the minimization of total free energy. The anisotropic character of the physical quantities and the effects of growth temperature have been shown both on the surface energy per unit volume through its dependence on the oxygen chemical potential and on the strain energy density through its variation with the elastic strain and biaxial modulus. Importantly, it is demonstrated by thermodynamic simulations that the oxygen chemical potential increases with growth temperature in the spray pyrolysis conditions, showing that the atmosphere is less and less reducing. For low growth temperature, it is revealed that the ã1 0 1ã preferred orientation is due to surface energy minimization since the (1 0 1) reduced surfaces have a surface energy lower than the (1 0 0) reduced surfaces. In contrast, as growth temperature is raised, the ã1 0 0ã crystallographic orientation becomes predominant owing to strain energy minimization. A texture map is finally determined, revealing the expected texture as a function of elastic strain and oxygen chemical potential.
Related Topics
Physical Sciences and Engineering
Materials Science
Ceramics and Composites
Authors
V. Consonni, G. Rey, H. Roussel, B. Doisneau, E. Blanquet, D. Bellet,