The present study focuses on the effect of Cu incorporation into magnetron sputtered alumina films. The transformation phenomena in an Al-O film and Al-Cu-O films with varying Cu content (1.4-9.6 at%) were studied using differential scanning calorimetry (DSC) and X-ray diffraction in combination with ab-initio calculations. In the Al-O film, only an exothermic transformation of an as-deposited γ-Al2O3 structure into α-Al2O3 is observed. In the Al-Cu-O films an exothermic decomposition of an as-deposited metastable solid solution into α-Al2O3 and CuAl2O4 was observed with a successive endothermic decomposition of CuAl2O4. In the Al-Cu-O film with 1.4 at% Cu the α-Al2O3 phase forms at a considerably lower temperature (∼1000 °C) compared to the Al-O film (∼1150 °C). The increasing Cu content results in an increase of thermal stability of the metastable solid solution and a decrease of (i) the concentration of octahedral Al vacancies and (ii) transformation energy of this solution upon heating.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Process Chemistry and Technology
- Surfaces, Coatings and Films
- Materials Chemistry