Publicação
An experimental and theoretical study on the crystal structure and elastic properties of Ta1-xOx coatings
| Resumo: | The production of Ta1-xOx coatings has attracted a lot of attention due to their wide variety of industrial applications. Nonetheless, to properly control the functional properties of these coatings, a good understanding of their structural properties must be achieved. Ta1-xOx phases have structural similarities since they are formed by the distortion of the body centered cubic (bcc) Ta structure and, therefore, a clear and unequivocal identification of the crystalline phases is not trivial. In this regard, this work proposes a theoretical and experimental study to understand the evolution of the structural and the elastic properties of Ta-based coatings. The coatings were deposited by magnetron sputtering as a function of oxygen content and characterized by EPMA (electron probe microanalysis), XRD (X-ray diffraction), STEM (scanning transmission electron microscopy) and SAW (surface acoustic waves). The results demonstrate the formation of a bcc alpha-Ta phase in the non-reactive Ta coating, which transitions to a mixture of crystalline tantalum and tantalum oxide phases for low oxygen concentrations while amorphous phases are observed for high oxygen levels. Ab-initio calculations of different Ta-O phases are in good agreement with the experimental results and reveal that the oxygen addition to the metallic Ta phase, leads to a distortion of the Ta crystal structure, causing a decrease in density and an increase of the elastic constants. |
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| Autores principais: | Almeida Alves, C. F. |
| Outros Autores: | Marques, L.; Calderon, S. V.; Ferreira, P. J.; Schneider, D.; Cavaleiro, A.; Carvalho, S. |
| Assunto: | Tantalum oxide coatings Magnetron sputtering Ab-initio STEM Elastic modulus |
| Ano: | 2019 |
| País: | Portugal |
| Tipo de documento: | artigo |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | The production of Ta1-xOx coatings has attracted a lot of attention due to their wide variety of industrial applications. Nonetheless, to properly control the functional properties of these coatings, a good understanding of their structural properties must be achieved. Ta1-xOx phases have structural similarities since they are formed by the distortion of the body centered cubic (bcc) Ta structure and, therefore, a clear and unequivocal identification of the crystalline phases is not trivial. In this regard, this work proposes a theoretical and experimental study to understand the evolution of the structural and the elastic properties of Ta-based coatings. The coatings were deposited by magnetron sputtering as a function of oxygen content and characterized by EPMA (electron probe microanalysis), XRD (X-ray diffraction), STEM (scanning transmission electron microscopy) and SAW (surface acoustic waves). The results demonstrate the formation of a bcc alpha-Ta phase in the non-reactive Ta coating, which transitions to a mixture of crystalline tantalum and tantalum oxide phases for low oxygen concentrations while amorphous phases are observed for high oxygen levels. Ab-initio calculations of different Ta-O phases are in good agreement with the experimental results and reveal that the oxygen addition to the metallic Ta phase, leads to a distortion of the Ta crystal structure, causing a decrease in density and an increase of the elastic constants. |
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