Thin solid films of metastable rocksalt structure (c-) Sc1-x Alx N and Ti1-x Alx N were employed as model systems to investigate the relative influence of volume mismatch and electronic structure driving forces for phase separation. Reactive dual magnetron sputtering was used to deposit stoichiometric Sc0.57 A l0.43 N (111) and Ti0.51 Al0.49 N (111) thin films, at 675°C and 600°C, respectively, followed by stepwise annealing to a maximum temperature of 1100°C. Phase transformations during growth and annealing were followed in situ using x-ray scattering. The results show that the as-deposited Sc0.57 Al0.43 N films phase separate at 1000-1100°C into nonisostructural c-ScN and wurtzite structure (w-) AlN, via nucleation and growth at domain boundaries. Ti0.51 Al0.49 N, however, exhibits spinodal decomposition into isostructural coherent c-TiN and c-AlN, in the temperature interval of 800-1000°C. X-ray pole figures show the coherency between c-ScN and w-AlN, with AlN (0001) ScN (001) and AlN 0 1̄ 10 ScN 1̄ 10 . First-principles calculations of mixing energy-lattice spacing curves explain the results on a fundamental physics level and open a route for design of novel metastable pseudobinary phases for hard coatings and electronic materials.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - Jun 2 2010|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics