Face-Centered Cubic (Al1-xCrx)2O3 Thin Films: Deposition, Characterization, and Heat Treatment Studies
2011 (English)Conference paper, Presentation (Other academic)
Face centered cubic (Al1-xCrx)2O3 solid solution films, with x in the range 0.60<x<0.70, have been deposited using dual reactive RF magnetron sputtering from Al and Cr targets in mixed Ar/O2 discharge at a substrate temperature of 500 °C. The films have a strong <100> preferred orientation. The unit cell parameter is 4.04 Å determined by x-ray diffraction and high resolution transmission electron microscopy techniques. The (Al1-xCrx)2O3 films are suggested to have a non-stoichiometric NaCl structure with 33% vacancy occupancy on Al/Cr sites. Nanoindentation shows that the films exhibit hardness values up to 26 GPa and reduced modulus of 220-235 GPa. In the present work, ex-situ annealing studies were performed on as-deposited samples for a series of temperatures up to 1100 °C and annealing time of 2,4,6,8, and 10 hours. The fcc structure remains intact up to 950 °C. A gradual phase transformation from fcc to corundum at 925 °C is observed, where annealing for 2 h yields a partial transformation and annealing for >6 h results in complete transformation to a-(Al1-xCrx)2O3. There is no indication of any phase separation into a-Cr2O3 and Al2O3.
Place, publisher, year, edition, pages
National CategoryManufacturing, Surface and Joining Technology Physical Sciences
IdentifiersURN: urn:nbn:se:liu:diva-84378OAI: oai:DiVA.org:liu-84378DiVA: diva2:558845
12th Conference on the European Ceramic Society (ECerS XII), 19-23 June 2011, Stockholm, Sweden