Face-Centered Cubic (Al1-xCrx)2O3 Thin Films : Deposition, Characterization, and Heat Treatment Studies

• Face centered cubic (Al1-xCrx)2O3 solid solution films, with x in the range 0.602 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.

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TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Bearbetnings-, yt- och fogningsteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Manufacturing, Surface and Joining Technology (hsv//eng)

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

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