Almeida Alves, C.F.C.F.Almeida AlvesMarques, Luís Silvino AlvesLuís Silvino AlvesMarquesCalderon, S.V.S.V.CalderonFerreira, Paulo J.Paulo J.FerreiraSchneider, DieterDieterSchneiderCavaleiro, Albano J.Albano J.CavaleiroCarvalho, S.S.Carvalho2022-03-052024-05-212022-03-052019https://publica.fraunhofer.de/handle/publica/25687410.1016/j.surfcoat.2019.02.054The 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 a-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.enTantalum oxide coatingsmagnetron sputteringab-initioSTEMelastic modulusLAwave621543671journal article