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arXiv · 1905.06714

Phase composition and transformations in magnetron-sputtered (Al,V)2O3 coatings

L. Landälv·C-F. Carlström·J. Lu·Daniel Primetzhofer·M. J. Jõesaar·M. Ahlgren·E. Göthelid·B. Alling·L. Hultman·P. Eklund
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Abstract

Coatings of (Al1-xVx)2O3, with x ranging from 0 to 1, were deposited by pulsed DC reactive sputter deposition on Si(100) at a temperature of 550 °C. XRD showed three different crystal structures depending on V-metal fraction in the coating: α-V2O3 rhombohedral structure for 100 at.% V, a defect spinel structure for the intermediate region, 63 - 42 at.% V. At lower V-content, 18 and 7 at.%, a gamma-alumina-like solid solution was observed, shifted to larger d-spacing compared to pure γ-Al2O3. The microstructure changes from large columnar faceted grains for α-V2O3 to smaller equiaxed grains when lowering the vanadium content toward pure γ-Al2O3. Annealing in air resulted in formation of V2O5 crystals on the surface of the coating after annealing to 500 °C for 42 at.% V and 700 °C for 18 at.% V metal fraction respectively. The highest thermal stability was shown for pure γ-Al2O3-coating, which transformed to α-Al2O3 after annealing to 1100° C. Highest hardness was observed for the Al-rich oxides, ~24 GPa. The latter decreased with increasing V-content, larger than 7 at.% V metal fraction. The measured hardness after annealing in air decreased in conjunction with the onset of further oxidation of the coatings.

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L. Landälv, C-F. Carlström, J. Lu, Daniel Primetzhofer, M. J. Jõesaar, M. Ahlgren, E. Göthelid, B. Alling, L. Hultman, P. Eklund. 2019-08-20. Phase composition and transformations in magnetron-sputtered (Al,V)2O3 coatings. https://doi.org/10.1016/j.tsf.2019.06.019

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