A novel route to realize controllable phases in an aluminum (Al~(3+))-doped VO_2 system and the metal-insulator transition modulation

摘要

The controllable Ml or M2 phases of Al~(3+) -doped VO_2 were successfully achieved through an effective and economical route, which combines a hydrothermal method and subsequent annealing treatment. The crystalline structure and the valence states of as-prepared samples were characterized by XRD, TEM, and XANES spectroscopy. Experiments showed that the Al~(3+) dopants and the Ar flux rates in an annealing process played the important roles in the formation of stable M2 phase. Microstructural characterizations by SEM indicated that the size of Al-doped VO_2 particles gradually reduced with increasing Al concentration. The phase transition property measured by DSC revealed that the metal-insulator transition temperature (T_C) could be tuned by the Al-doping concentration only in the formation of M2 phase.