An experimental and theoretical study on the crystal structure and elastic properties of Ta1-xOx coatings

SURFACE & COATINGS TECHNOLOGY

卷:364

Article

Almeida Alves, C. F.^1,3  Marques, L.²  Calderon, S. V.³  Ferreira, P. J.^3,4,5,6  Schneider, D.⁷  Cavaleiro, A.⁸  Carvalho, S.^1,8 

[1] Univ Minho, Dept Phys, CFUM UP, Campus Azurem, P-4800058 Guimaraes, Portugal

[2] Univ Minho, Dept Phys, CFUM UP, Campus Gualtar, P-4710057 Braga, Portugal

[3] INL Int Iberian Nanotechnol Lab, Ave Mestre Jose Veiga S-N, P-4715330 Braga, Portugal

[4] Univ Texas Austin, Mat Sci & Engn Program, Austin, TX 78712 USA

[5] Univ Lisbon, Dept Mech Engn, Ave Rovisco Pais, P-1049001 Lisbon, Portugal

[6] Univ Lisbon, Inst Super Tecn, IDMEC, Ave Rovisco Pais, P-1049001 Lisbon, Portugal

[7] Fraunhofer Inst Mat & Beam Technol IWS, D-01277 Dresden, Germany

[8] Univ Coimbra, Dept Mech Engn, SEG CEMMPRE, P-3030788 Coimbra, Portugal

关键词: Tantalum oxide coatings;    Magnetron sputtering;    Ab-initio;    STEM;    Elastic modulus;   

DOI  :  10.1016/j.surfcoat.2019.02.054

来源: Elsevier

【 摘 要 】

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.

【 授权许可】

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